Product Spotlight for 10/8/19: "ONcological TARGETing: Revisiting the RGDs"

The integrins are involved in many cellular processes including cell proliferation and differentiation and act as receptors for cell-adhesion molecules. A particular group of integrins are called the RGD-binding integrins and are named for the Arg-Gly-Asp (RGD) in their sequence.  This sequence is a cell attachment site and is recognized by several integrins. Many strategies for fighting diseases, such as cancer, target these RGD-binding integrins because they are easily accessible and inhibited by peptides, peptidomimetics, and monoclonal antibodies.1

With the advent of “click chemistry”, RGD peptides can have a lysine side chain amine converted to an azide for easy functionalization (see RGD-3759-PI). In cancer tumor imaging, several radiolabeled, cyclic RGD peptides have been found to be useful in integrin αvβ3-targeting. Integrin αvβ3 binding affinity is also increased by using a bicyclic RGD peptide.2-5 Peptides International is a known leader in RGD peptide products, especially dimeric and larger dendrimers of RGD peptides, all of which are part of its RGD Technology Platform. Peptides International now offers a RGD-PEG-PEG-azide peptide which is optimized for Click chemistry and facile synthesis of dendrimeric platforms with the corresponding alkyne component using a branching strategy. An example of a branching strategy of this type could use a template such as 5-hexynoyl-Lys(5-hexynoyl)-Gly-Lys(hexynoyl)-Gly-Lys(hexynoyl)-NH2. This would allow for preparation of the tetrameric form of the RGD dendrimer.

We urge you to explore all the RGD products and services we offer including our comprehensive RGD Technology Platform, a holistic approach that designed to support you from conception to market reality.

A selection of our RGD products:

NEW! RGD Peptides:


Control Peptide for RGD-3000-PI

Clickable RGD Peptides:

Clickable RGD for Dendrimer Constructs

Bicyclic RGD Peptide Optimized for Click Chemistry  

Dimeric RGD Peptide for Click Chemistry

Linear RGD Peptides:

Fibronectin Active Fragment (RGDS)
PFA-4171, PFA-4171-v (0.5 mg vial)
Arg-Gly-Asp-Ser ● ½AcOH ● 2H2O


Cell-Penetrating RGD peptide:

Ac-cyclo [Pen-Tyr(Me)-Ala-Arg-Gly-Asp-Asn-Tic-Cys]-NH₂
Cell-Penetrating Peptide that Targets EGFR, Binds to a Specific Protein in Carcinoma Cells, and Induces Apoptosis

Cyclic RGD peptides:

αvβ3 Integrin Binding RGD Peptide RGD Tumor Targeting Peptide

RGD Tumor Targeting Peptide (linker additions via Cys)

Cilengitide: Cyclo(Arg-Gly-Asp-D-Phe-N-Me-Val)
Selective Inhibitor of αvβ3 and αvβ5 with Possible Role in Tumor Therapy

View our complete list of RGD products
Read more about our RGD peptides
Read about Two Bicyclic RGD Peptides Optimized for Click Chemistry
Learn more about Click Chemistry


  1. C.-C. Sun, X.-J. Qu, & Z.-H. Gao, American Journal of Therapeutics, 23, e198 (2016).
  2. M. Colombo and A. Bianchi, Molecules, 15(1), 178 (2010).
  3. J. Shi, F. Wang, S. Liu, Biophysics Reports, 2(1), 1 (2016).
  4. S. Liu, Bioconjug Chem., 26(8),1413 (2015).
  5. S. Liu, Bioconjug Chem., 20(12), 2199 (2010).

Product Spotlight for 9/24/19: "Arboviral Diseases in the News"

From our previous Product Spotlight, which was our first Rare Disease Journal, we move over to the other end of the spectrum, to some of the most prevalent (and deadly) viruses known. We are speaking of mosquito-borne illnesses, and the following is a list of just of few that are transmitted by their parasites. Included along with a brief overview of the respective diseases, are our related products and some pertinent literature, appearing in both academic and general media recently.


Malaria is probably the most well-known to the general public of the diseases in this group and among tropical diseases generally. Approximately half the world’s population (about 100 countries) is at risk.1 Although the disease is prevalent, and attributed to 445,000 deaths as recently as 2016,2 there have been great strides toward decreasing the numbers of people afflicted, through vigorous government and NGO efforts. From 2010-2016 malaria mortality was reduced by 25%.2 For more interesting effects of mosquitos, and specifically, malaria, there is a book to recommend published last month, on the impact of the insect, entitled, The Mosquito A Human History of Our Deadliest Predator.  Even more recently, The Lancet commissioned a first-of-its-kind article (open access) which had 41 authors from across a broad range of specialties, with the promising title, Malaria Eradication Within a Generation: Ambitious, Achievable, and Necessary.

Malaria Pv. MSP1
Merozoite surface antigen is a protein located on the outside of the merozoite, playing an imperative role in immune reaction. About 45% cases of malaria are infected by Plasmodium vivax (Pv). Pv. MSP1 has to be used with Plasmodium falciparum (Pf) together for ELISA and rapid diagnostic testing. Plasmodium falciparum and vivax infection covers about 95% of Plasmodium -caused infection.

Malaria Pf. MSP1
About 55% cases of malaria are infected by Plasmodium falciparum (Pf). Pf MSP1 has to be used with Plasmodium vivax (Pv) together for ELISA and rapid diagnostic testing.

Haptoglobin Human
Haptoglobin is a glycoprotein which is synthesized in the liver and circulates in the blood. Haptoglobin is produced typically by hepatocytes but also by other tissues: e.g. skin, lung, and kidney. It is a positive acute phase protein that binds free hemoglobin and removes it from the circulation to prevent kidney injury, and iron loss following hemolysis. The haptoglobin-hemoglobin complex is subsequently removed by the reticuloendothelial system (generally the spleen). As the reticuloendothelial system removes the haptoglobin-hemoglobin complex from the body, haptoglobin levels are reduced in hemolytic anaemias. In the course of binding hemoglobin, haptoglobin sequesters the iron inside hemoglobin, preventing iron-utilizing bacteria from benefitting from hemolysis.
Haptoglobin consists of two a- and two b-chains, connected by disulfide bonds. Three major haptoglobin phenotypes are known to exist (Hp 1-1, Hp 2-1, and Hp 2-2). Hp 1-1 is biologically the most effective in binding free hemoglobin and suppressing inflammatory responses associated with free hemoglobin. Hp 2-2 is biologically the least active, and Hp 2-1 is moderately active. Haptoglobin’s molecular mass ranges from 8-200 kDa.

Reduced levels can be seen in haemolysis and impaired liver function. High levels are a marker for acute or chronic inflammation. Ahaptoglobinemia or hypohaptoglobinemia are caused by mutations in the haptoglobin gene and/or its regulatory regions. Haptoglobin is also linked to diabetic nephropathy, the incidence of coronary artery disease in type 1 diabetes, Crohn's disease, inflammatory disease behavior, primary sclerosing cholangitis, susceptibility to idiopathic Parkinson's disease, and a reduced incidence of Plasmodium falciparum malaria.

West Nile

As the leading cause of domestically acquired arboviral disease in the continental United States,3 a cursory look at search results for the West Nile virus just lists many pages of new occurrences of outbreaks in new regions. According to the CDC, that is the case: incidences were 25% more common than usual in 2018, and transmission patterns appeared to shift to new regions.4

WNV Envelope


West Nile virus (WNV) is a virus of the family Flaviviridae part of the Japanese encephalitis (JE) antigenic complex of viruses. Image reconstructions and cryoelectron microscopy reveal a 45-50 nm virion covered with a relatively smooth protein surface. This structure is similar to virus; both belong to the genus flavivirus within the family Flaviviridae. WNV is a positive-sense, single strand of RNA, it is between 11,000 and 12,000 nucleotides long which encode seven non-structural proteins and three structural proteins. The RNA strand is held within a nucleocapsid formed from 12 kDa protein blocks; the capsid is contained within a host-derived membrane altered by two viral glycoproteins.

With headlines last month such as, “Philippines Declares a National Dengue Epidemic,” this resurgent disease has killed at least 622 this year in just that country alone. Promisingly, there has also been a vaccine approved by the US Food and Drug Administration (FDA) in May, the first of its kind. Unfortunately, the WHO recommends it only for persons that have had confirmed, prior dengue virus infections.5 In the US, as of September 4, 2019, provisional data states that this year there have been 38 states and the District of Columbia reporting a total of 408 cases, with nearly all being travel related.6  

Finally on an individual, very personal level, here is an interesting case, published in the Sunday New York Times Magazine, from their popular column, “Diagnosis”, on some of various ways the Dengue virus can present.

Peptides International has dozens of Dengue virus related products; here are just a couple:

Dengue Virus Subtype 1 & 3 Fused Envelope 58kDa Recombinant
The E.coli derived recombinant 58kDa protein is a genetically engineered peptide which is derived from Dengue Type-1 and 3 to be expressed as a fused envelope, each part in this fusion contains 170 a.a (positions 46-217), it is used in ELISA assay. This fusion protein is connected to a 6xHis Tag.

Dengue Virus NS1 Subtype 2 Recombinant
Recombinant Dengue Virus NS1 Subtype 2 produced in Insect Cells is a polypeptide chain containing amino acids 777-1131 and having a molecular weight of approximately 50kDa.


Longtime readers may be familiar with PI’s “Zika Virus Updates,” a series we instituted during the height of the outbreak. There have been some more developments to report. Earlier this month, it was published in an open access article from Nature Communications that the risk from the virus is not just confined to pregnant or soon-to-be pregnant mothers and their children.7 Understandably, given past publicity of the risks, personal protective measures were greater among female US travelers at least, as shown in a recent study.8 Yet with the Nature Communications study, complacency among the male adult population may be ill-advised. However, in a report from just over a year ago, researchers tested a novel formulation of three free-form amino acids (FFAAP)—cystine, glycine, and glutamate, as well as a minute amount of selenium—that was previously known to increase biosynthesis (or production) of glutathione, an antioxidant, within cells. The Zika virus was inhibited up to 90% in the study.9 On another promising front, a diagnostic test that was given market approval by the US FDA hopefully will remove fear and confusion from those that were possibly exposed or visited affected areas.10

Here are two of our Zika-related products:

Zika Envelope
Zika virus (ZIKV) belongs to the family Flaviviridae and the genus Flavivirus, it is transmitted by daytime-active Aedes mosquitoes, such as A. aegypti and A. albopictus. The Zika virus is related to the dengue, yellow fever, Japanese encephalitis, and West Nile viruses. Much like the other flaviviruses, Zika virus is enveloped and icosahedral and has a non-segmented, single-stranded, positive-sense RNA genome. Zika fever is an infection, which often causes no symptoms or only mild ones, like a mild form of dengue fever, and it is treated by rest. As of February 2016, there has been mounting evidence that Zika fever in pregnant women can cause abnormal brain development in their fetuses by mother-to-child transmission, which may result in miscarriage or microcephaly. Furthermore, a connection has been established with neurologic conditions in infected adults, including Guillain–Barre syndrome. Since the 1950s, Zika virus has been detected only within a narrow equatorial belt from Africa to Asia. Between the years 2013 and 2014, Zika virus has spread eastward across the Pacific Ocean to French Polynesia, New Caledonia, the Cook Islands, and Easter Island, and in 2015 to Mexico, Central America, the Caribbean, and South America, where the Zika outbreak has reached pandemic levels.

Zika NS1 Paired Antibody/Mouse Anti Zika NS1 Paired
Zika NS1 conjugation antibody and Zika NS1 capture antibody are used to develop rapid test for Zika NS1 rapid test.




Product Spotlight for 9/12/19: "Rare Disease Journal Inaugural Edition - BBS"

With this Product Spotlight, we are instituting a new feature that looks at “Rare Diseases”.  This designation is not an arbitrary one.  In order to qualify as a rare disease, its incidence rate must affect less than 200,000 people as established by the Congress of the United States with the Orphan Drug Act of 1983.1  In fact, the legislation, in addition to creating the definition, was also instrumental in changing the entire discussion and economy around orphan drug research in the US.  For example, during the ten years prior to its implementation, less than ten treatments were approved. However, since1983, the Office of Orphan Products Development (OOPD), which incentivizes research on what were previously untenable developmental costs, has been integral to bringing more than 400 new treatments to market. 1

There are believed to be upwards as many as 7,000 rare diseases according to the NIH.  Within their numerous centers, one, the National Center for Advancing Translational Sciences (NCATS), studies commonalities found among populations and diseases through collaborative studies.1 From that, the following programs for rare diseases have been made available:

Of course, with increased and vigorous reporting, collaborations, computer models, and even communications, the designations and prevalence of rare, and in fact, all diseases may change over time.


Our inaugural Rare Disease Journal outlines one of these officially designated rare diseases, BBS (Bardet Biedl Syndrome), which is thought to affect approximately 1 in 250,000 worldwide. About 3,000 are believed to be affected in the US and Canada, if the ratios are correct.2

The rare genetic disorder is marked by retinal degeneration, obesity, reduced kidney function, polydactyly (extra digits of the hands or feet) and many other characteristics. Although more than 20 genes have been associated with BBS, the underlying cause regardless of gene is malfunction of primary cilia, a key component of cellular communication. BBS is thus categorized as a ciliopathy, or a disease of the cilia.2

There have been over eighteen primary and secondary symptoms categorized by UK researcher Dr. Philip Beales, with a diagnosis requiring four primary symptoms or three primary and at least two of the secondary characteristics.2

Protein misfolding, chaperonin proteins (eg., Heat Shock Proteins), and cilia dysfunction are all avenues for researching BBS. 

Peptides International has services applicable to this disease, including custom peptide synthesis with post-translational modification, along with a range of related products, some of which are listed below.

RL4D is a developmentally regulated member of the ADP-ribosylation factor/ARF-like protein (ARF/ARL) family of Ras-related GTPases. Small GTP-binding protein which cycles between an inactive GDP-bound and an active GTP-bound form, and the rate of cycling is regulated by guanine nucleotide exchange factors (GEF) and GTPase-activating proteins (GAP). ARL4D takes part in membrane-associated intracellular trafficking. Mutations in this gene is linked to Bardet-Biedl syndrome (BBS).

ARL4D Human

ARL6 is a member of the ARF family of GTP-binding proteins. ARL6 has a vital part in modulating membrane trafficking and cytoskeletal functions. Mutation in ARL6 is the source of Bardet-Biedl syndrome (BBS3) which is a pleiotropic genetic disorder that causes obesity, photoreceptor degeneration, polydactyly, hypogenitalism, renal abnor-malities and developmental delay.

ARL6 Human

Leptin Antagonist Triple Mutant Human Recombinant is a single non-glycosylated polypeptide chain containing 146 amino and additional Ala at N-terminus acids and having a molecular weight of 16 kDa, Leptin was mutated, resulting in L39A/D40A/F41A. Leptin Antagonist Triple Mutant Human Recombinant was purified by proprietary chromatographic techniques.

Leptin tA Human

Leucine Zipper Transcription Factor-Like 1, also known as LZTFL1, is a ubiquitously expressed protein which localizes to the cytoplasm. LZTFL1 interacts with Bardet-Biedl Syndrome proteins (BBS) and during its interaction with BBS protein complexes, regulates protein trafficking to the ciliary membrane. Nonsense mutations in LZTFL1 cause a form of Bardet-Biedl Syndrome; a ciliopathy characterized partly by polydactyly, obesity, cognitive impairment, hypogonadism, and kidney failure. LZTFL1 also acts as a tumor suppressor; possibly by interacting with E-cadherin as well as the actin cytoskeleton and in this manner regulating the transition of epithelial cells to mesenchymal cells.

LZTFL1 Human



Additional Reading

BBS4 regulates cilia function in the olfactory sensory system
Genetic testing for Bardet-Biedl syndrome 

Product Spotlight for 8/27/19: "Six Brilliant Little (Spot) Lights"

Instead of a single topic or item being featured in the Spotlight this week, we are combining some of our shorter "miniSpotlights" that we have posted on our website since the inaugural post in May, with the hopes that you will find something of interest.

Biologically Active Peptides

Substance P (PSP-4014-v, PSP-4014) is a member of the tachykinin neuropeptide family. The tachykinins have roles in nociception, pain, inflammation, and more recently in gut motility.1,2
Synonyms/Product Alternate Names: H-Arg-Pro-Lys-Pro-Gln-Gln-Phe-Phe-Gly-Leu-Met-NH2, RPKPQQFFGLM-NH2
New publication on Substance P: Substance P and Inflammatory Pain: Getting It Wrong and Right Simultaneously

  1. C. Severini, et al., Pharmacological Reviews, 54(2), 285 (2002).
  2. L. Palamiuc, et al., Nature Communications, 8, 14237 (2017).

OVA Peptide (257-264) (POV-3659-PI), or Chicken ovalbumin fragment (257-264),is T-cell activating peptide and the epitope from ovalbumin.
Synonyms/Product Alternate Names:H-Ser-Ile-Ile-Asn-Phe-Glu-Lys-Leu-OH, SIINFEKL
(related peptide: OVA Peptide (323-339), POV-3636-PI)
New publications on OVA (257-264):
Virus-specific memory T cells populate tumors and can be repurposed for tumor immunotherapy
Identification of epitopes in ovalbumin that provide insights for cancer neoepitopes

Lugdunin (LUG-3871-PI)is a “macrocyclic thiazolidine peptide antibiotic”. It is produced by the human nasal Staphylococcus lugdunensis strains and inhibits the colonization of Staphylococcus aureus. S. aureus, also known as “staph” bacteria, is often implicated in many human infections. Lugdunin may hold promise in the search for antibiotic alternatives, since current research suggests that it may be difficult for bacteria to develop a resistance to Lugdunin.1

Synonyms/Product Alternate Names: cyclo(D-Leu-Val-D-Val-2-[1S-1-amino-2-methylpropyl]-Thiapro-D-Val-Trp)
We recently came across an interesting publication on Lugdunin and analogues:
Synthetic Lugdunin Analogues Reveal Essential Structural Motifs for Antimicrobial Action and Proton Translocation Capability

From our archives: New and Improved Antimicrobial Peptides!
A. Zipperer, et al., Nature, 50, 511 (2016).

Enzyme Inhibitors and Substrates

E-64 (IES-4096, IES-4096-v) is an irreversible cysteine protease inhibitor. It reacts with the active site cysteine thiol to form a thioether. E-64 stimulates endothelial cell response to wounds1 and has been found to inhibit calpain, cathepsin B, H,and L, and papain, to name a few.
Synonym/Product Alternate Name: (L-3-trans-Ethoxycarbonyloxirane-2-Carbonyl)-L-Leucine (3-Methylbutyl)Amide

We also carry the analogs, E-64c (IEC-4320-v) and E-64d (IED-4321-v). E-64d is a potent and irreversible cathepsin B inhibitor with greater cell-permeability than E-64.
New publication mentioning E-64: Anionic Phospholipids Induce Conformational Changes in Phosphoenolpyruvate Carboxylase to Increase Sensitivity to Cathepsin Proteases
R. N. Mascardo & G. Eilon, Journal of Pharmacology and Experimental Therapeutics, 244 (1), 361(1988).

Tools for Peptide Synthesis

Fmoc-MeDbz (FMD-2331) is a useful linker in peptide synthesis, and, in particular, in preparing key C-terminal peptide thioester intermediates in native chemical ligation (NCL). The MeDbz group is also less prone to acetylation during sold-phase peptide synthesis (SPPS) than the first generation Nbz linker.

Synonym: 3-[(9-Flurenylmethyloxycarbonyl)Amino]-4-(Methylamino)Benzoic Acid
CAS Number: 1788861-35-7
J.B. B-Canosa, B. Nardone, F. Albericio, & P.E. Dawson, J. Am. Chem. Soc., 137, 7197 (2015).

Additional reading:Exploiting the MeDbz Linker to Generate Protected or Unprotected C‐Terminally Modified Peptides

Product Spotlight for 8/13/19: "Check Out These New AIPs, ASAP"

As first described in 1970, quorum sensing was observed in the marine bacterium Aliivibrio fischeri.1 Quorum sensing, the process of cell to cell communication, is a crucial component of bacterial virulence. Bacteria use it to detect and regulate cell population densities. The requirements of bacteria to perform quorum sensing are three-fold: the ability to secrete a signaling molecule, followed by the ability to secrete an autoinducer, and finally, the capacity to regulate gene transcription. These abilities together allow bacteria to perform activities typically thought of in higher-level organisms, such as communication and organization.2

With the prevalence and virulence of Methicillin-resistant Staphylococcus aureus (MRSA), the promise of Autoinducing Peptides (AIPs) is in their ability to disrupt the second link required of this triumvirate. Approximately one in three people carry S. aureus bacteria in their nose, usually without any illness. The incidence of MRSA is less: about two in every 100 people carry it and most do not develop serious MRSA infections. However, it is a major problem in a hospital setting, often leading to sepsis, which is the body’s extreme response to an infection and often turns fatal.3  Misuse of antibiotics has made treatment of MRSA challenging, to say the least, and there is a hunt for antibiotic alternatives. With these issues in mind, we have just introduced three new AIPs, as modulators of accessory gene regulator (Agr) quorum sensing in Staphylococcus aureus.

Also of possible interest:

Aryl hydrocarbon receptor (AHR) interacting protein (AIP) may have a positive role in AHR-mediated (aromatic hydrocarbon receptor) signaling, probably by influencing its receptivity for ligand and/or its nuclear targeting. AIP is a Cellular negative regulator of the hepatitis B virus (HBV) X protein. Furthermore, AIP is a ubiquitously expressed protein, which binds to HSP 90 and AHR through a highly conserved carboxy-terminal tetraticopeptide repeat domain.

AIP Human Recombinant is produced in E. coli, and is a single, non-glycosylated polypeptide chain containing 350 amino acids (1-330 a.a.) and having a molecular mass of 39.8kDa. AIP is fused to a 20 amino acid His-tag at the N-terminus and purified by proprietary chromatographic techniques.

  • Aryl Hydrocarbon Receptor Interacting Protein Human Recombinant
    AH receptor-interacting protein, AIP, Aryl-hydrocarbon receptor-interacting protein, HBV X-associated protein 2, XAP-2, Immunophilin homolog ARA9, XAP2, ARA9, FKBP16, FKBP37, SMTPHN


1. Nealson, K.H.; Platt, T.; Hastings, J.W. (1970). "Cellular control of the synthesis and activity of the bacterial luminescent system". Journal of Bacteriology. 104 (1): 313–22. PMC 248216. PMID 5473898.

Product Spotlight for 7/30/19: "Deoxyfructosyl Peptides/Amino Acids"

Reducing sugars such as glucose are known to glycate proteins by non-enzymatic reaction with amino groups of proteins in vivo. The series of reactions is known as the Maillard reaction starting from Amadori rearrangement, and the modified compounds are called Amadori compounds and/or Maillard compounds. After oxidation and dehydration reaction, it leads to AGEs (Advanced Glycation End Products). AGEs typified by Pentosidine have been reported to affect age-related diseases.

Figure 1. Amadori rearrangement reaction of D-glucose with N-terminal Val residue of hemoglobin in vivo.

Glycated hemoglobin A1c (HbA1c) is an Amadori compound in which blood glucose is bound to the N-terminal Val residue of hemoglobin β chain. HbA1c is used as a diagnostic marker for diabetes, and its amount can be measured by the enzymatic method, as shown in Figure 2.
Figure 2. Measurement of HbA1c by enzymatic method.

We have released several deoxyfructosyl products in small package sizes.







1 mg vial




1 mg vial



1-Deoxyfructosyl-Val [Fru-Val]

1 mg vial



1-Deoxyfructosyl-Val-His [Fru-Val-His]

1 mg vial




1 mg vial


Bulk quantities, as well as custom synthesis of different glycosylation reaction products such as 3-Deoxyglucosone (3-DG) / Carboxymethyl Lysine (CML), and AGEs, are available on request. Please feel free to contact us.


  1. U. Kobold, J.O. Jeppsson, T. Duelffer, A. Finke, W. Hoelzel, and K. Miedema, Clin. Chem., 43, 1944 (1997).
  2. T. Nakanishi and A. Shimizu, J. Chromatogr. B, 746, 83 (2000).
  3. K. Hirokawa, K. Gomi, and N. Kajiyama, Biochem. Biophys. Res. Commun., 311, 104 (2003).

Product Spotlight for 7/16/19: "Another Treasure-Trove of New Catalog Releases"

As we have recently mentioned (in the Product Spotlight of 5/21/19, "A Plethora of New Products to Peruse"), we have been releasing such a large number of new items from our own lab and adding so many from our partners, that our Marketing Department is in the enviable position of trying to decide just which to feature! Therefore, we occasionally we like to showcase sundry items unrelated to any topic or theme in order to clear up to the backlog!

Biologically Active Peptides

  • β-Defensin-1 (Mouse)
    (M.W. 4070.6) C168H266N52O54S6
    (Disulfide Bonds Undetermined)

  • Candidalysin
    (M.W. 3310.1) C153H266N38O38S2    [1906866-53-2]
    Fungal Cytolytic Peptide Toxin

  • Caloxin 2A1
    (M.W. 1478.5) C64H91N19O22    [350670-85-8]
    Selective Plasma Membrane Ca2+-Pump Inhibitor

  • CPN-267
    (M.W.1051.2) C50H66N16O8S
    Human NMUR1 Selective Agonist

  • Dns-Glu(Cys-Gly)
    (M.W. 540.61) C22H28N4O8S2
    Trapping Agent for the Quantitative Estimation and Identification of Reactive Metabolites

  • EGF (Human)
    (M.W. 6215.9 ) C270H395N73O83S7    [62253-63-8]
    (Disulfide Bonds Between Cys6-Cys20, Cys14-Cys31, and Cys33-Cys42)
    Growth Factor that Stimulates Cell Growth, Proliferation, and Differentiation Synthetic Product

    Epidermal Growth Factor (EGF) EGF is a 6-kDa protein consisting of 53 amino acids residues with three intermolecular disulfide bonds.  It was originally isolated from the sub-maxillary glands of mice by Cohen.  EGF stimulates the cell proliferation and differentiation by binding the receptor EGFR.

  • L17E Cytosolic Delivery Peptide
    (M.W. 2859.4) C134H220N38O31     [1898254-09-5]
    Peptide for Transport to Cytoplasma

  • Vasoconstriction-Inhibiting Factor (Human)
    (M.W. 908.1) C163H256N42O67S
    Endogenous Modulator of Vasoconstrictive Effect of Angiotensin II

Specialty Products & Technologies

  • Prorenin (314-337) (Human)
    Antisera, Origin: Rabbit
  • PSA (53-92) (Human)
    Antisera, Origin: Rabbit
  • Glucagon-HS ELISA (Kit)
    Antisera ELISA Kit Manufactured by the Yanahara Institute

Tools for Peptide Synthesis

  • Fmoc-N-Amido-dPEG®5 Acid
  • Hydroxy-dPEG®8-t-Butyl Ester
    (M.W. 498.6)    [1334177-84-2]

We hope you will find something of interest to your research. However, should you need an item that is truly unique, please contact us for a custom peptide synthesis quotation. With a quick reply times, quality and value, strict confidentiality, proactive project management, and friendly service, bringing your research dreams to reality has never been easier. 

Product Spotlight for 7/2/19: "Diabetes And Alzheimer's Disease Related Products"

Our featured items here are in concert with this week’s PepTalk on the interesting new research looking at possible connections between Alzheimer’s disease and diabetes.

The first grouping is Dipeptidyl Peptidase-4 (DPP-IV) Inhibitors and related offerings.  DPPIV is an intrinsic membrane glycoprotein and a serine exopeptidase that cleaves X-proline dipeptides from the N-terminus of polypeptides. DPP4 plays a role in t-cell activation and is associated with intracellular signal transduction, apoptosis and involved in tumor biology. DPP4 plays a major role in glucose metabolism by cleaving incretins such as glucose-dependent insulinotropic polypeptide (GIP) and glucagon-like peptide-1 (GLP-1).

  • Human-Dipeptidyl-Peptidase-IV

  • Dipeptidyl-Peptidase IV Human Recombinant
  • Gly-Pro-MCA
    (M.W. 329.35) C17H19N3O4     [67341-42-8]
    Substrate for X-prolyl Dipeptidyl-Aminopeptidase IV (DPP-IV)
  • Gly-Pro-pNA • Tos [GPNT]
    (M.W 292.29 • 172.20)  C13H16N4O4 • C7H8O3S     [65096-46-0]
    Substrate for X-prolyl Dipeptidyl-Aminopeptidase IV (DPP-IV)

The second main group featured are those incretins mentioned above, GLP-1 agonists.

The native hormone of Exendin-4 (Exenatide) is produced in the gut of Gila monster Heloderma suspectrum (a reptile found in the desert) that stimulates insulin production without causing threateningly low blood sugar, which can occur after using insulin and some anti-diabetes products.

  • Exendin-4 (synthetic)
    (M.W. 4186.66) C184H282N50O60S     [141758-74-9]
    GLP-1 (Glucagon-Like Peptide-1) Receptor Agonist

  • Exenatide (recombinant)

We recently featured Liraglutide in another PepTalk on fibril formation comparing it to GLP-1. Liraglutide is an acylated variant of human GLP-1 (7-37). The selective fatty acylation of the peptide increases the half-life to 11-15 hours following a subcutaneous injection allowing for once daily injection. This peptide drug has been widely used to treat type II diabetes.

  • Liraglutide
    (M.W. 3751.29) Formula: C17H265N43O51     [204656-20-2]
    Glucagon-Like-Peptide-1 (GLP-1) Receptor Agonist

Semaglutide is a glucagon-like peptide-1 (GLP-1) analogue and a GLP-1 receptor agonist. Not only does it have a half-life of up to one week, it has been used in type 2 diabetes research for its ability to stimulate insulin production while suppressing glucagon secretion in a glucose-dependent manner. Semaglutide has an increased albumin affinity and exhibits a three-fold decrease in GLP-1 receptor affinity when compared to liraglutide.1 Recent studies in patients with type 2 diabetes suggest that semaglutide may also have an improved cardiovascular outcome in those patients who are at risk for a cardiac event.2      

  • Semaglutide
    (M.W. 4113.67) C187H291N45O59     [910463-68-2]
    Glucagon-Like Peptide-1 (GLP-1) Analog Shown to Stimulate Insulin and Suppress Glucagon Secretion in a Glucose-Dependent Manner
  1. J. Lau, et al., J. Med. Chem., 58, 7370 (2015). Retrieved from
  2. S.P. Marso, et al., N. Engl. J. Med., 375, 1834 (2016). Retrieved from

Originally discovered by Zealand Pharma, Lixisenatide was licensed and developed by Sanofi for its use in the treatment of type 2 diabetes. GLP-1 is a naturally occurring peptide, released shortly after a meal has been consumed.

  • Lixisenatide
    (M.W. 4858.60 C215H347N61O65S     [320367-13-3]
    Potent and Highly Selective Once-Daily GLP-1 Peptide Agonist

Of course, this list is just a smattering of the many related items we have available. 

Fmoc-N-Amido-dPEG®5 Acid


Hydroxy-dPEG®8-t-Butyl Ester
(M.W. 498.6)    [1334177-84-2]




 We hope you will find something of interest to your research. However, should you need an item that is truly unique, please contact us for a custom peptide synthesis quotation. With a quick reply times, quality and value, strict confidentiality, proactive project management, and friendly service, bringing your research dreams to reality has never been easier.

Product Spotlight for 6/18/19: "Hang Your Chemistry Ideas On These PEGs"

Peptides International is known for doing difficult peptide sequences.  When we do those syntheses, we turn to the very products we offer in our catalog to ensure the quality we require is also the quality we offer to others. In the last Product Spotlight, we put the focus predominately on resins, and in the PepTalk featured OxymaPure® from Luxembourg. So, this time we thought it would be nice to showcase some of the many new monodisperse, discrete PEG derivatives (dPEG®) that we offer from Quanta BioDesign.

 The dPEG®s are not purified from a polymeric mixture and hence contain no other PEG homologues (only the one selected as the desired product), resulting in a single compound with a single molecular weight. Using dPEG®s should significantly decrease cost and time associated with synthesis by reducing problems associated with using conventional PEGs.

We have recently added many new dPEG® products to our offerings, with more frequently joining the list. As we mentioned, we also utilize the products we offer in our laboratories. Accordingly, if you should find yourself needing either a custom peptide that incorporates a dPEG® item or even looking for custom synthesis of a dPEG® reagent, please contact us today.

Please click through the respective products’ code links for more details on specific items.

Amino-dPEG®₁₂-Tris (-dPEG®₂₄-t-Butyl Ester)₃
(M.W. 4490.37; single compound)

Azido-dPEG®₁₂-TFP Ester
(M.W. 791.78; single compound)
Tool for Click Chemistry

Azido-dPEG®₄-TFP Ester
(M.W. 439.36; single compound)
Tool for Click Chemistry

(M.W. 3478.328; single compound)

(M.W. 786.54; single compound)

(1147.35; single compound)

Bis-dPEG®₁₇-PFP Ester

Tool for Click Chemistry

Bromoacetamido-dPEG®₁₂-TFP Ester
(886.71; single compound)

(339.19; single compound)
Tool for Click Chemistry

(1220.24; single compound)
Tool for Click Chemistry

Bromoacetamido-dPEG®₄ -TFP Ester
(534.29; single compound)

Bromoacetamido-dPEG®₂₄-TFP Ester
(1415.35; single compound)

(M.W. 3000.75; single compound)

(M.W. 3363.04; single compound)

(3306.083; single compound)

(3391.14; single compound)

(M.W. ; 4753.34; single compound)

Finally, here are just features of just some of the many dPEG® subcategories:

dPEG® Biotinylation Reagents

  • Very water soluble, hydrophilic, and eliminates non-specific binding.
  • Non-antigenic and non-immunogenic spacer arm.
  • The dPEG® pegylation spacer and its properties eliminates aggregation and precipitation when labeling antibodies and other biological materials, and will also significantly increase S/N in analytical applications as well.

dPEG® Biotin Acid

  • Imparted physical properties of the biotin are the same as the dPEG®X NHS esters (DPG-5701, DPG-5703); the labeled compound becomes very hydrophilic because of the dPEG® pegylation spacer, making the biotin very available for streptavidin binding in the capture/binding step.
  • The DPG-5705 pegylation spacer is the same length as DPG-5701 and DPG-5703, respectively, and its length is optimal for rapid and tight avidin/SAbinding properties.
  • Very water soluble, hydrophilic and eliminates non-specific binding.
  • DPG-5703 has a longer 47.6 Angstrom spacer: the longer pegylation arm gives ready accessibility to the biotin by the streptavidin/avidin conjugate binding; also where the amine of the biotinylation site may be buried, the longer arm is ideal for giving accessibility to the binding conjugates.
  • Non-antigenic and non-immunogenic spacer arm.
  • The dPEG® pegylation spacer and its properties eliminates aggregation and precipitation when labeling antibodies and other biological materials, and will also significantly increase S/N in analytical applications as well.

Amino-dPEG®t-Butyl Esters

  • A carboxy-protected dPEG®x amino acid pegylation reagent.
  • •dPEG® pegylation spacer and modifier with a reactive amine and a t-butyl protected carboxylic acid.
  • dPEG® pegylation spacer is extremely hydrophilic, will enhance the water solubility of a compound in which it is incorporated, and reduce non-specific binding where applicable. The spacer is also non-immunogenic. The ester is water-soluble and soluble in commonly used organic solvents of moderate polarity.
  • The t-Butyl group:
    –      Is easily removed with TFA (25% TFA in CH2Cl2, ice bath/0° C, takes about 5 h).
    –      Provides a potentially powerful purification handle due to its hydrophobicity. Subsequently it is removed to perform additional chemistry. This applies best when using normal phase (e.g., silica gel) chromatography.
    –      Neutralizes the zwitterion of the amino acid for better reactivity at the amine.
    –      Reacts with carboxylic acids and other carbonyls.


  • Convenient mono-protected dPEG diamine for pegylation - selectively react just one end, then subsequently deprotect with TFA to make other amine available for reaction.
  • Hydrophilic, non-immunogenic dPEG® pegylyation spacer.
  • Water soluble with pegylation spacer.

Quanta dPEG® products are protected under U.S. Patents #7,888,536 & 8,637,711

G.T. Hermanson, Bioconjugate Techniques, 3rd Edition, Elsevier, Waltham, MA 02451, 2013, ISBN 978-0-12-382239-0; See chapter 18, Discrete PEG Reagents, pp.787-821, for a full overview of the dPEG® products.


Product Spotlight for 6/4/19: "Do You Need Space - Or To Make Links?"

Peptides International is your one-stop shop for all things peptide related. Not only are we experts in peptide synthesis, as seen by our large catalog of biologically active peptides, enzyme substrates and inhibitors, and custom synthesis services, our proteins and cytokines, did you know that we also carry reagents and tools for peptide synthesis?

Amino Acid Derivatives

Click Chemistry Amino Acids


Reaction Vessels and Related Glassware

Reagents, featuring OxymaPure®

And many more.

This week we spotlight our mini-PEGS and CLEAR products.

Tools for Peptide Synthesis

Peptides International carries a variety of mini-PEG™s.  They are versatile spacers and solubilizing linkers.  In RGD peptides, for instance, they act as spacers between ligand and lipid head groups, to allow for more efficient binding to lipid surfaces.

Fmoc-mini-PEG™ / Fmoc-AEEA
Synonyms/Product Alternate Names: Fmoc-8-Amino-3,6-Dioxaoctanoic Acid; 9-Fluorenylmethoxycarbonyl-8-Amino-3,6-Dioxaoctanoic Acid
(M.W. 385.42) C21H23NO6     [166108-71-0]

Fmoc-mini-PEG™-3 (syrup) / Fmoc-AEEEA                                
Synonyms/Product Alternate Names: 9-Fluorenylmethoxycarbonyl-8-Amino-3,6,9-Trioxaundecanoic Acid; Fmoc-11-Amino-3,6,9-Trioxaundecanoic Acid (Syrup); Fmoc-mini-PEG™-3 Fmoc-11-Amino-3,6,9-Trioxaundecanoic Acid (Syrup)
(M.W. 429.47) C23H27NO7     [139338-72-0]

Boc-mini-PEG™ / Boc-AEEA                                             
Synonyms/Product Alternate Names: Boc-8-Amino-3,6-Dioxaoctanoic Acid • DCHA; tert-Butyloxycarbonyl-8-Amino-3,6-Dioxaoctanoic Acid • Dicyclohexylamine; Boc-mini-PEG™
(M.W. 263.29 • 181.3) C11H21NO6 • C12H23N     [560088-79-1

Boc-mini-PEG™-3 / Boc-AEEEA                                        
Synonyms/Product Alternate Names: Boc-11-Amino-3,6,9-Trioxaundecanoic Acid • DCHA; tert-Butyloxycarbonyl-11-Amino-3,6,9-Trioxaundecanoic Acid • Dicyclohexylamine
(M.W. 307.35 • 181.32) C13H25NO7 • C12H23N

 8-Azido-3,6-Dioxaoctanoic Acid
Synonyms/Product Alternate Names: Azido-mini-PEG™ CHA salt; 8-Azido-3,6-Dioxaoctanoic Acid
A Building Block for Click Chemistry

H-mini-PEG™-2-ClTrt-Resin (100-200 mesh) 1% DVB
For preparation of acids, alcohols, thiols, or amines

Specialty Products & Technologies

CLEAR™ Resins
CLEARTM (Cross-Linked Ethoxylate Acry-late Resins) were developed by George Barany and Maria Kempe at the University of Minnesota and is produced in a bead form using a large-scale polymerization process developed at Peptides International. Not only do they have a highly desirable solvation property of PEG resins, they are highly cross-linked solid-supports and can be used in a variety of different applications, from automated or manual solid-phase peptide synthesis (SPPS), to organic synthesis, affinity chromatography, enzyme immobilization, trace analysis, or remote sensor applications. Do you need to use a non-polar solvent?  Besides DCM, DMF, and water, CLEAR are also compatible with the relatively non-polar solvents, THF and dioxane. Read more about CLEARTM here.

CLEAR-Acid Resin (100-200 mesh)

CLEAR-Amide Resin (100-200 mesh) (0.3 - 0.5 meq/g)

CLEAR-Base Resin (HCl) (100-200 mesh)

In addition to the CLEAR™ Resins, we also carry CLEAR-OXTM, a polymer-supported oxidant, which combines the power of solid phase chemistry with the versatility of solution-phase reactions. CLEAR-OXTM is a highly effective, polymer-supported reagent for the formation of disulfide-bonds. CLEAR resin is the polymer of choice due to its compatibility with both aqueous and organic environments. A lysine-preformed cyclic Ellman’s reagent [5,5’-dithiobis(2-nitrobenzoic acid) = DTNB] is covalently attached to a CLEAR™ polymeric support with a β-alanine spacer to yield CLEAR-OXTM. Since the mechanism is based on peptide capture, sensitive residues such as Tyr, Trp, and Met are not affected, leading to increased purity and yield. These improved synthetic conditions allow for facile removal of the oxidant. Read more about CLEAR-OXTM and download resin conditioning and general methods here.


Product Spotlight for 5/21/19: "A Plethora of New Products to Peruse"

Peptides International, with the help of some of our valued partners, has been releasing so many products in the last few months, it is clear that featuring just a few every two weeks in the Product Spotlight will not allow us to showcase all of them in a timely manner. Therefore, this edition is intended to simply give a broad overview of the many new products that have been released, but not yet featured. We plan to do more in-depth articles on many of these at a later date.

Biologically Active Peptides

Cellular Housekeeping
CIF1                                                                 CIF-4499-s

Neuroscience Peptides
β-Ala-Lys(AMCA)                                             PBP-3412-v

Plant Based Peptides
CLE25 Peptide                                                 PBP-4511-v
TDIF [CLE41/44 Peptide]                                 PBP-4512-v

RGD Peptides
Asp-Asn-Tic-Cys]-NH₂                                     RGD-3035-PI
Celingitide                                                       RGD-3036-PI

APETx2                                                           APE-4472-s
τ-CnVA (Tau conotoxin CnVA):
H-ECCHRQLLCCLRFV-NH2                          CON-3847-PI

Enzyme Inhibitors and Substrates

Suc-Phe-Ala-Ala-Phe-pNA                               SUB-3007-PI
Urokinase-Derived Peptide A6                         UPA-3038-PI

Tools for Peptide Synthesis

Amino Acids
Fmoc-L-Ser((Ac)3-β-D-Xyl)-OH                       FSX-1924-PI
Galacturonic Acid                                             SAA-1928-PI

TentaGel® Microsphere NH2 Resin (20 um)    TMN-9909-PI

Recombinant Proteins 

TINAGL1 Human, Sf9                                      PRO-2422
YWHAE Human, His                                        PKA-095
PSIP1 Human                                                  PRO-2267
Aprotinin Recombinant                                    PRO-285
FKBP1A Mouse                                               ENZ-871

We hope you will find something of interest to your research. However, should you need an item that is truly unique, please contact us for a custom peptide synthesis quotation. With a quick reply times, quality and value, strict confidentiality, proactive project management, and friendly service, bringing your research dreams to reality has never been easier.

Product Spotlight for 5/7/19: "A Family of Natural Born Killers"

A family of serine proteases known as Granzymes are found in the lytic granules of cytotoxic T lymphocytes and natural killer (NK) cells. Both are involved in the killing of susceptible target cells1, which include virally infected cells and tumor cells,2 making them of interest in treating cancer and infections.

There are different types of granzymes that have been identified since their discovery by Jürg Tschopp's group,3,4 including Granzyme A, B, H, K, and M.

Peptides International is pleased to offer two new items, one an inhibitor of, and the other a substrate of Granzyme M.  We also have numerous other granzyme- and apoptosis-related products, with just a sampling listed below.

(M.W. 697.8) C35H51N7O8
Selective Fluorogenic Substrate for Granzyme M

(M.W. 530.10) C25H441N5Cl    [1176290-36-0]
Selective Inhibitor for Granzyme M

Other Related Products

Granzyme-K Human Recombinant

Non-Metastatic Cells 1 Human Recombinant

Ac-Ile-Glu-Thr-Asp-MCA [Ac-IETD-MCA]
(M.W. 675.68) C31H41N5O12      [348079-17-4]

Ac-Ile-Glu-Thr-Asp-H (Aldehyde)
(M.W. 502.52) C21H34N4O10     [191338-86-0]
Inhibitor for Caspase-8/6 and Granzyme B (Deduced from the Cleavage Site of Procaspase-3)

Gwilz [CC BY-SA 4.0 (]

Please click through each link for details of the specific products, and should you want a custom peptide synthesis variant of these or any other items, please contact us for a quote.



Simon Caulton [CC BY-SA 3.0 (]

Related References of Interest:

L. Wu, L. Wang, G. Hua, K. Liu, X. Yang, Y. Zhai, M. Bartlam, F. Sun, and Z. Fan, J. Immunol., 183, 421 (2009). (Original)
S. Mahrus, W. Kisiel, and C.S. Craik, J. Biol. Chem., 279, 54275 (2004). (Original)
S. Mahrus and C.S. Craik, Chem. Biol., 12, 567 (2005).

Product Spotlight for 4/23/19: "HA Peptide - No Laughing Matter for Researchers"

The hemaglutinin (HA) protein, a surface glycoprotein, is responsible for binding the influenza virus to sialic acid receptors, initiating infection. The HA Peptide corresponds to amino acids 98-106 of the HA protein and is the hemagglutinin epitope, a general epitope tag in expression vectors.  This tag can be used to outcompete anti-HA antibody binding to HA-tagged fusion proteins in immunoassays since it is easily recognized by hemagglutinin antibodies.1

One encouraging strategy is to combat influenza viruses by inactivating the fusion process between the viral and host membranes.2

Additionally, there was a publication that reported an αβ T‐cell receptor (αβTCR)/hemagglutinin (HA) peptide/human leukocyte antigen (HLA)‐DR1 complex was secured by connecting HA peptide with human HA1.7 αβTCR, to increase the local concentration of the interacting proteins once the peptide has been loaded onto the major histocompatibility complex (MHC) molecule.3

HA Peptide is also been used for cosmeceutical applications.4

HA Peptide
(M.W. 1102.18) C53H67N9O17    [92000-76-5]

Please click through the link for details of this product, and should you want a custom peptide synthesis variant of the HA Peptide or any other, please contact us for a quote.


  1. K. Sekikawa & C.-J. Lai, Proc.Nat.Acad.Sci., 80, 3563 (1983).
  2. D. Lousa, et al., Free Radical Biology and Medicine, 120 (1), S125 (2018).
  3. J. Hennecke, et al., The EMBO Journal, 19, 5611 (2000).
  4. R. Teschke, Int. J. Mol. Sci., 20(1), 211 (2019).

Product Spotlight for 4/9/19: "A Quartet of 'Controllers'"

The incidence of metabolic syndrome (MetS) worldwide has markedly surged with industrialized development and improved food distribution.1 It is marked by the presence of obesity by waist circumference and two or more of the following characteristics1:

  1.  Hypertriglyceridemia: ≥ 150 mg/dL, or under treatment for this lipid abnormality.
  2. HDL-cholesterolemia below recommendations:
  3. Hypertension: systolic ≥ 130 mmHg and/or diastolic ≥ 85 mmHg over 24 h.
  4. Fasting Hyperglycemia: ≥100 mg/dL, hyperinsulinemia, or type 2 diabetes.

With this increased rate, the need for an array of resources will be needed to mitigate its effects.   Currently there is a shortage of insulin available, and it is especially acute among developing countries. The purchase of insulins can consume as much as 10% of government expenditure on drugs.2

Research that may provide alternative solutions would be beneficial to countless people worldwide. To that end, Peptides International has a diverse and broad portfolio of feeding-regulatory products, with many applications for research of MetS, along with numerous other endocrine-associated diseases.

The most recent to be added are four offerings representing both peptides and proteins.

We featured Relaxin-3 (PRO-2176) just last fall and now we are adding another pair, Relaxin-2 Human Recombinant (PRO-1327)and Relaxin-2 (Human) (REX-4509-v).They may have other roles in boosting sperm motility, regulating blood pressure, controlling heart rate and releasing vasopressin. RLN2 is a peptide hormone linked to several therapeutically relevant physiological effects, including regulation of collagen metabolism and multiple vascular control pathways.

Our third product has recently released corresponding items too. Those were featured in a PepTalk from late February: Neuromedin U Precursor-Related Peptide 36 (Rat, Mouse) (PMN-4506-s), Neuromedin S Precursor-Related Peptide 37 (Rat) (PNM-4507-s), and Neuromedin S Precursor-Related Peptide 37 (Mouse) (PMN-4508-s). Now we also have Neuromedin S (Mouse) (PNM-4496-s).

The fourth member of this quartet is Pentosidine (SAE-3242-v) which is an Advanced Glycation End Product (AGE) and a biomarker for glycation-oxidative stress (e.g. in type 2 diabetes and aging).


M. Etchegoyen, M.H. Nobile, F. Baez, B. Posesorski, J. González, N. Lago, J. Milei and M. Otero-Losada, Front. Neurosci., 12, 196 (2018). doi: 10.3389/fnins.2018.00196
G.V. Gill, J.S. Yudkin, H. Keen, D. Beran, Diabetologia, 54, 1 (2011).

Product Spotlight for 3/26/19: "Spiders Do It: Gomesin and Melanoma"

Gomesins are antimicrobial peptides that were first derived from spider venoms. AgGom was initially isolated from the tarantula, Acanthoscurria gomesiana, and its analog, HiGom, was then isolated from the Australian funnel-web spider, Hadronyche infensa. Both have 18 amino acids, differing by only two (in bold, below), and have proven anticancer activity. A recent study demonstrated that they induce apoptosis in melanoma cells.1 Given these results, gomesin analogs have potential in melanoma-targeting therapies.

As experts in the synthesis of venom and toxin compounds, we are pleased to introduce two new gomesin analogs, AgGom and HiGom:

Disulfide Bonds: Cys2-Cys15 and Cys6-Cys11

Disulfide Bonds: Cys2-Cys15 and Cys6-Cys11

We invite you to take a look at our other toxins here. If you are interested in a custom toxin, or any other product or service, please contact us here.  See what the bees are busy doing too, in this week's PepTalk.


1. M.P. Ikonomopoulou, et al., Scientific Reports, 8, 11519 (2018). 


Product Spotlight for 3/12/19: "Do You Need A NAP (Peptide)?"

NAPVSIPQ, also commonly known by the acronym NAP, is an eight-amino acid neuroprotective peptide.1 It has been shown to offer cognitive protection in patients with amnesic mild cognitive impairment, which is a precursor to Alzheimer's disease.2

This peptide fragment is derived from Activity-Dependent Neuroprotective Protein (ADNP) and may stabilize microtubule breakdown, indicating a useful avenue of investigation of therapeutic strategies for Parkinson's, Alzheimer's and related diseases.3

A recent paper suggests that application of this small peptide, results in a reduction of aluminum ion neurotoxicity.  It is believed that the aluminum ion-induced accumulation of β-amyloid 1–42 may cause risk of Alzheimer’s disease.4 

Peptides International has recently added NAP peptide to our extensive neurological research and more specifically, to the Alzheimer’s disease product line.

NAP Peptide
Trifluoroacatate Salt
Synonyms/Product Alternate Names: Davunetide; ADNP Neuropeptide Fragment; H-Asn-Ala-Pro-Val-Ser-Ile-Pro-Gln-OH
(M.W. 824.94) C36H60N10O12    [11439-12-2]

I. Goezes, et al., Front Mol Neurosci., 11, 151 (2018).
I. Goezes, et al., CNS Drug Review, 11(4), 353 (2005).
S. Qurasishe, et al., Sci Rep., 6, 38224 (2016).
S. Vaisburb, et al., Sci Rep., 5, 16300 (2015).



Product Spotlight for 2/26/19: "New Neuromedins"

New research on a connection between feeding-regulation and the Neuromedin U Receptor 2 protein is covered in the PepTalk this week, so it is a good time to reintroduce the Neuromedins and unveil a few new product releases.

Neuromedin U (NMU) was discovered first in porcine spinal cord and seen to cause constriction of the uterus and other smooth skeletal muscle. Neuromedin S, an isoform of Neuromedin U, was first found in the rat brain in suprachiasmatic nucleus (SCN) and later NMU-17 and 33 were discovered in bombina frog venoms. Both are vasoconstrictors and regulate hormonal levels. Neuromedin B and Neuromedin C have a structure similar to Bombesin and are similar to Gastrin releasing peptide (GRP). Neuromedin K, or Neurokinin B, and Neuromedin L, Neurokinin A, are a part of the tachykinin family. Neuromedin N has similar properties to neurotensin, and both come from the same precursor.1

Along with the associated seventeen others we offer, including Neuromedin S (Human), Neuromedin S (Rat), Neuromedin U (Human), Neuromedin U (Mouse), Neuromedin U (Rat), and Neuromedin U8 (Porcine), we are introducing three more releases to these two related S and U classes.


  1. S. Gajjar & B. Patel., Pharmacological Reports, 69(3), 438 (2017).


Product Spotlight for 2/12/19: "Research Focus On Breast (and other) Cancer Part II"

Continuing with our "Research Focus: Breast Cancer" theme, this week’s Product Spotlight highlights additional products that may be useful in Breast Cancer research. Last issue's Product Spotlight had more proteins than peptides featured.  So this time we are inverting the ratio, and therefore predominately highlighting peptides.

First up are three TAPI (TNF-Alpha Protease Inhibitor) products, and all of these are Matrix Metalloproteinases (MMPs) inhibitors.  MMPs are involved in the degradation of the extracellular matrix (ECM) and are thought to provide a pathway for invasion by cancerous tumor cells. 

We have a recent Product Spotlight that looked at MMPs that you can view here as well.

Bombesin, originally isolated in the skin of the frog bombina, is a tumor marker for carcinomas, being present in 68% of bronchial carcinoids, 65% pulmonary neuroendocrine carcinomas, 62% of neuroendocrine carcinomas of the skin.1 It is thought to act like a growth factor in tumor tissue.2

Somatostatin-14, or somatotropin release-inhibiting factor (SRIF), inhibits growth hormone and has several active octapeptide derivatives. One of those, Octreotide, is a somatostatin analog and plays a role in downregulating MMP-2 and may hinder tumor invasion and metastasis.

We invite you to take a look at another cancer spotlight: "LH-RH and other Neurohormones for Cancer Research" and a past PepTalk, “Target: Cancer. Mission: Search & Destroy” for additional, related products.


  1. G. Chejfec, I. Lee, W.H. Warren, V.E. Gould, Peptides, 6 Suppl 3, 107 (1985).
  2. D.W. Kufe et al., editors, Holland-Frei Cancer Medicine, 6th ed, Hamilton (ON): BC Decker; 2003.
  3. C.-Z Huang et al.,Cell Physiol Biochem, 47, 2340 (2018).


Product Spotlight for 1/29: "Research Focus On Breast Cancer"

As part of this week’s newsletter's thematic "Research Focus: Breast Cancer" issue, we are training the Spotlight on a few of the items that are applicable to that field of study, along with some more general oncology tools.

First up is a selection from our estimable RGD portfolio.

  • Galacto-RGD2
    When 99mTc-labeled, this cyclic RGD dimer is a useful tool for tumor imaging.1

The next group is pulled from our vast Recombinant Proteins category:

  • ErbB3 Mouse
    ErbB3, also called Her3 (human epidermal growth factor receptor 3), is a type I membrane glycoprotein that is a member of the ErbB family of tyrosine kinase receptors. ErbB family members serve as receptors for the epidermal growth factor (EGF) family of growth factors. Among ErbB family members, ErbB3 is unique in that it contains a defective kinase domain. ErbB3 is expressed in keratinocytes, melanocytes, skeletal muscle cells, embryonic myoblasts and Schwann cells. Monomeric ErbB3 serves as a low affinity receptor for the heregulins (HRG). ErbB3 can induce specific antibody production in vivo, hence to inhibit tumor cell growth. ErbB-3 can be used to treat early, medium and advanced or post-operative breast cancer with over-expression of ErbB2. According to its mechanism of action, ErbB3 is classified as a therapeutic for cancer. 2
  • HEXIM1
    HEXIM1 expression is induced by hexamethylene-bis-acetamide in vascular smooth muscle cells. HEXIM1 is a transcriptional regulator that acts as a universal RNA polymerase II transcription inhibitor. In cooperation with 7SK snRNA sequesters P-TEFb in a large inactive 7SK snRNP complex inhibits RNA polymerase II phosphorylation following transcriptional elongation. HEXIM1 regulates NF-kappa-B, ESR1, NR3C1 and CIITA-dependent transcriptional activity. 3
  • Prolactin Human
    Prolactin is a neuroendocrine hormone synthesized primarily by the pituitary gland but also a variety of other cell types including the placenta, brain and uterus. Its primary function is to promote and maintain lactation but has also been shown to have a role in breast cancer development, regulation of reproductive function and immunoregulation. 4
  • ZNRD1 Human
    Zinc Ribbon Domain Containing 1 (ZNRD1) is a protein which shows similarity to the Saccharomyces cerevisiae Rpa12p subunit of RNA polymerase I. ZNRD1 contains two potential zinc-binding motifs and takes part in regulation of cell proliferation. ZNRD1 is involved in cancer and human immunodeficiency virus progression. 5

Our last entry is similar to another immunosuppressant in its structure, but its properties are quite different. While Prograf (FK506) suppresses T lymph cells from proliferating from G0 to G1 stage, our offering uses different cytokine receptors to block signal transduction, thus preventing T lymph cells and other cells from proliferating from G1 to S stage.6

  • Rapamycin

Rapamycin is a clinically useful immunosuppressant that inhibits the response to interleukin-2 blocking activation of T- and B-cells and induces autophagy. Rapamycin forms a complex with cytosolic FK-binding protein 12 (FKB12) that binds to mTOR Complex1 (mTORC1), inhibiting the mammalian target of rapamycin (mTOR). The mTOR pathway is very active in several types of breast cancer since mTOR is an important player in cell proliferation and blocking it may be a useful therapy.7


  1. S. Ji, A. Czerwinski, Y. Zhou, Gl Shao, F. Valenzuela, P. Sowinski, S. Chauhan, M. Pennington, and S. Liu, Mol. Pharmaceutics, 10, 3304 (2013).
  7. P. Malaguti et al., Anticancer Res.33(1), 21 (2013).


The Product Spotlight for 1/15/19"New Year, New Products"

The start of the year has already seen some new additions to the Peptides International catalog. The first set of new products we are releasing and featuring for 2019 come from the Peptide Institute. The ones below are part of the Carbohydrate and Conjugates group, and are all Amadori compounds. These derivatives of aminodeoxysugars, are formed in food as part of the Maillard reactions.


During the cooking process, the nose can sense when food is cooked by detecting the “browning” aromas released during the Maillard reaction. The Maillard reaction takes place in the absence of enzymes and produces cooking flavors, colors, and aromas through a reaction with reducing sugars and amino acids.  There are several steps in the process of forming Maillard reaction products (MRPs), and one such step is the Amadori rearrangement.1  Some Amadori compounds have a variety of antioxidant and anti-inflammatory bioactivities,2 whereas others are fragments of the N-terminus of glycated hemoglobin.3 We are pleased to offer several Amadori compounds, or aminodeoxysugars:











The Product Spotlight for 12/18/18: "The Year In Review, By the Numbers"

2018 was another big year for new products released by Peptides International.  Of course a number of these were from our select group of distributors, which allows for a broad network and portfolio of offerings, yet the year saw many new products originate from PI’s own labs as well. There were over 130 additions, in total for 2018.

RGD Peptides
One of the flagship product lines, RGD peptides, was represented by two entries. Named for the Arg-Gly-Asp (RGD) in their sequence, they are a cell attachment site for many proteins and are involved in many cell processes including cell proliferation and differentiation. Many strategies for fighting disease target these RGD-binding integrins because they are easily accessible and inhibited by peptides, peptidomimetics, and monoclonal antibodies.1

Antisera Comes On Strong
The Antisera category has had few additions over the last few years, but 2018 turned out to be a very active year. There were no less than 40 antisera, and these were predominately ELISA kits and diabetes research products. The undiluted antisera are suitable for immunohistochemical use, for application to RIA, or other non-isotopic immunoassay purposes. These antisera are partially characterized by either EIA or ELISA. The following represents just one-tenth of the antisera added this year:

Cell penetrating peptides have the ability to cross cell membranes and can be conjugated with cargo molecules which can be internalized into a cell with the cargo remaining intact. These peptides have the ability to deliver payloads that can inhibit or interrupt intracellular function. Cell penetrating peptides have really shown increasing interest to drug discovery researchers in the last few years and is growing category at PI as well, with three new products just in the last few months.

  • H-[Lys-Leu-Ala-Lys-Leu-Ala-Lys]2-Gly-Phe-Leu-Gly-(Cys-Gln-Thr-Pro-Tyr-Tyr-Met-Asn-Thr-Cys)-OH CAN-3505-PI
  • Biotinylated Tat (47-57) TAT-3841-PI
  • Tat (47-57) TAT-3768-PI

Recombinant Proteins
Since including the recombinant protein category a few years ago – by far our biggest catalog product section, with over 4000 currently available – there have been dozens more added each subsequent year. In 2018 we added over two dozen, with applications ranging from Parkinson’s disease, cancer, and cell adhesion.

New Categories Added
One important development was adding categorization of catalog products by their applications to disease state research. For example, while it is useful to some end-users to know the categories of products by their types (“What is it?”), many researchers would also want to know their application to their investigations (“What is it for?”). This ongoing project, when completed, should prove especially useful when searching for products on the website.

To date, these are the disease states that products are being tagged with:

It is our hope that this organizational structure will make it even easier to find relevant information and our products when searching

For a complete list, we invite you to take a look at our New Products Brochure. For the most up-to-date and comprehensive list of products, please visit our online catalog. As usual, we offer discounts on bulk quantities and have custom peptide synthesis services. Contact us today to learn more.

Thank you for your patronage in 2018 and we hope you have a happy New Year!


  1. C.-C. Sun, X.-J. Qu, & Z.-H. Gao, American Journal of Therapeutics, 23, e198 (2016). Abstract retrieved from

The Product Spotlight for 12/4/18"Positioning Peptides Against Pain"

Since the company’s earliest days to our current 35th year, Peptides International has always been guided by the statement, “Research today. Cures tomorrow.” Peptide venoms have made that phrase a reality in a few cases. As outlined in this week’s PepTalk, one of the abiding health concerns in the United States right now is the search for safe alternatives to opioids for pain management. One such interesting drug actually to have originated from venom peptides is Prialt (ziconotide) (for the treatment of chronic intractable pain, which comes from Conus magus (ω-conotoxin MVIIA). In addition to it, there are other inhibitors of the voltage-gated sodium channel NaV, and specifically NaV1.7 that are of interest. The following are some of the peptide venoms that that Peptides International offers for this area of research:

In addition to the catalog offerings presented here, the Disulfide-Rich Peptide Experts at Peptides International’s custom peptide synthesis team can create with items to meet your exacting specifications.

Product Spotlight for 11/14/18

The Renin-Angiotensin System (RAS) is responsible for controlling blood pressure, sodium balance, and body fluid homeostasis. Angiotensin is a substrate of renin that cleaves a 10-residue peptide from the N-terminus, producing Angiotensin I, which is subsequently cleaved by the angiotensin converting enzyme (ACE) to form Angiotensin II. Angiotensin II is an 8-residue peptide and the most active product of the RAS system. It binds to specific receptors and triggers a range of events that impact nearly every body system. ACE inhibitors, which disrupt the formation of Angiotensin II, have been used successfully for the treatment of kidney diseases, congestive heart failure, and hypertension. Meanwhile, Bradykinin is an important biologically active peptide substrate for ACE. Bradykinin plays a role in lowering blood pressure and may also play a protective role in kidney function in diabetics. 1

Angiotensin I (Human)
0.5mg net vial  PAN-4007-v
25mg PAN-4007


Angiotensin II (Human)
0.5mg net vial PAN-4001-v
25mg PAN-4001


Angiotensin (Human, 1-7)
0.5mg net vial PAN-4332-v
25mg PAN-4332

Click here for more Angiotensin peptides.


Bradykinin (Human, Bovine, Rat, Mouse)
0.5 mg net vial PBK-4002-v

Click here for more Bradykinin fragments.

Click here for products related to Renin, including substrates and inhibitors.


  1. M.A. Sparks et al., Compr Physiol., 4(3), 1201 (2014).

Read more about Bradykinin here, including its role in inflammation and apoptosis in Parkinson’s Disease.

Product Spotlight for 10/29/18

Latest New Products!

Peptides International is pleased to offer a treasure trove of new products. The new items run the gamut from cell-penetrating peptides, such as two new Tat sequences, to RGD peptides, a collagen-like peptide, an MMP substrate, several new recombinant proteins, and many more. For a complete list, we invite you to take a look at our New Products Brochure. For the most up-to-date and comprehensive list of products, please visit our online catalog. As usual, we offer discounts on bulk quantities and have custom peptide and organic synthesis services. Contact us today to learn more.

Antimicrobial Peptide:

  • Cryptdin-4 (Mouse) PDF-4504-s
    The Most Potent Microbicidal of the Mouse Paneth Cell α-Defensins and is Degraded by MMP-7.

Collagen-like Peptide:

Cell-Penetrating Peptides:

  • H-[Lys-Leu-Ala-Lys-Leu-Ala-Lys]2-Gly-Phe-Leu-Gly-(Cys-Gln-Thr-Pro-Tyr-Tyr-Met-Asn-Thr-Cys)-OH CAN-3505-PI
  • Biotinylated Tat (47-57) TAT-3841-PI
  • Tat (47-57) TAT-3768-PI

Fucose Probes for Glycan Imaging:

MMP-2/MMP-9 Substrate:

  • Ac-Pro-Leu-Gly-(2-Mercapto-4-Methylpentanoyl)-Leu-Gly-OEt MMP-3060-PI
    A Leukocyte Collagenase Substrate.

Peptides for Cancer Research:

  • 5(6)-Carboxyfluorescein-(Cys-Gln-Thr-Pro-Tyr-Tyr-Met-Asn-Thr-Cys)-OH CAN-3984-PI
    A Fluorescein-Labelled Peptide That Binds to a Specific Protein in Carcinoma Cells, Induces Apoptosis, and Inhibits EGFR Autophosphorylation.

RGD Peptides:

Recombinant Proteins:

  • Parkinson Disease Protein 2 Human Recombinant PRO-1840
  • Parkinson Disease Protein 7 Mouse Recombinant PRO-2226
  • Relaxin-3 PRO-2176

Synthesis Reagent:

This reagent is used for the synthesis of Canaline-containing peptides. It is a derivative of ornithine, a naturally occurring amino acid with an O-alkyl hydroxylamine side chain that is produced by arginase from Canavanine. Due to its toxicity, by its ability to form oximes with carbonyl-containing biomolecules, it is produced by legumes as protection from herbivores. L- Canaline possesses anti-tumor activity against human acute leukemia T-cells, and as a result is of interest in cancer research. It also possesses antimalarial and antineoplastic properties.

Virology Peptides:


Product Spotlight for 10/15/18

GPCRs and PAR Peptides

G-protein-coupled receptors (GPCRs) are a large, diverse eukaryotic membrane group. They handle messaging for cells and signal the presence or absence of essential nutrients or other useful information sent by other cells. They are also binding sites for many cell signaling molecules. As a result, many pharmaceutical drugs on the market target GPCRs. In diabetes, GPCRs play a role in regulating hormones essential for maintaining blood glucose. In cancer, responses to tumors and cell growth are mediated by GPCRs and they also are a binding site for ligands and their overexpression is often seen in tumors. The Proteinase-activated receptors (PARs) are a diverse member of the GPCR family. They are activated primarily by proteases and are comprised of 4 types, with PAR1, PAR3, and PAR4 being activated by thrombin and PAR2 activated by trypsin. Upon protease cleavage, a tethered ligand is exposed at the N-terminus that is able activate intracellular signaling by binding to a conserved region in the second extracellular loop. PAR1 and PAR2 are expressed by a wide number of tumor cells including breast and colon cancers, suggesting a role in angiogenesis. PAR-activating peptides (PAR-APs) mimic the tethered ligand domains of the PARs and can activate by stimulating receptors in a protease-independent manner. Peptides International offers a variety of PAR-AP agonists and antagonists for your research needs.

2. B.T. Layden et al., Nature Education, 3(9),13 (2010).
3. R. Lappano & M. Maggiolini, Acta Pharmacol Sin., 33(3), 351 (2012).

For more information on PAR-APs, take a look at our recently updated brochure here.

Product Spotlight for 9/30/18

LH-RH and other Neurohormones for Cancer Research

Luteinizing hormone-releasing hormone (LH-RH), or gonadotropin-releasing hormone (GnRH), is secreted by the hypothalamus and triggers the pituitary gland to release the hormones, follicle-stimulating hormone (FSH) and luteinizing hormone (LH) that make estrogen and progesterone in females and testosterone in males. Since some cancers require or respond to estrogen or testosterone in order to grow, agonists of LHRH are often used as treatment.1 Growth hormone releasing factor (GRF or GHRH) is important in many cellular processes and in sleep promotion. It was first isolated from a pancreatic tumor.1 And lastly, Human Chorionic Gonadotropin (hCG) is released during pregnancy, however, research has found that some tumors express it, making it a useful tumor marker.3,4 When circulated during pregnancy, it has also been found to provide long-term protective effects against breast cancer.5 The following are some of the neurohormones that Peptides International carries for cancer research, and are also included in the current sale.

LH-RH (Human)
PLR-4013 (25mg, 100mg), PLR-4013-v (0.5mg vial), HOR-261

LHRH Protein

Anti LH-RH (Human, Rat) Serum (50 ul)

Anti Pro-LH-RH (1-26) (Human) Serum (50 ul)

Antide Acetate
GnRH/LHRH antagonist


GnRH/LH-RH super-agonist

PGR-4127-s (0.1mg vial), PGR-4127-v (0.5mg vial)


Leuprolide Human
GnRH/LH-RH agonist


SRIF(Somatotropin Release Inhibiting Factor)/GIF(Growth Hormone Release Inhibiting Factor)

PSI-4023 (25mg), PSI-4023-v (0.5mg vial), HOR-299

Triptorelin Acetate
GnRH/LH-RH agonist

Kisspeptin-10 (Human)
Stimulator of LH-HR/GnRH and gonadotropin secretion

Kisspeptin-10 (Rat)

Chorionic Gonadotropin Human (hCG)

Chorionic Gonadotropin Beta Human Recombinant



Product Spotlight for 9/14/2018

Probing the Matrix

As featured in our current sale and PepTalk, the Matrix Metalloproteinases (MMPs) are zinc-dependent endoproteinases.1 MMPs are involved in the degradation of the extracellular matrix (ECM) and are thought to provide a pathway for invasion by cancerous tumor cells. Peptides International carries both the MMP substrates and inhibitors as well as the proteinases themselves.

The TAPI (TNF-Alpha Protease Inhibitor) analogs have been shown to block TNF-α processing and also to inhibit L-selectin action by inhibiting the formation of a key precursor protein. They are inhibitors for Collagenase, MMP, and α-Tumor Necrosis Factor.

MMP substrates, on the other hand, are used in spectrophotometric assays of many matrix metalloproteinases. The table below is a useful cross-reference the MMP substrates that are carried by Peptides International.

For a complete list of MMP products, click here to view them on the Peptides International website. Specific substrates and inhibitors can also be synthesized by design to meet your research needs. Contact us today if you need help locating an item, procuring a bulk quotation, or designing a custom peptide.


  1. P. Van Lint & C. Libert, J Leukoc Biol., 82(6), 1375 (2007).
  2. L. Sun et al., Biomater. Sci., (2018). Advance Article

Product Spotlight for 8/28/2018

Products for Breast Cancer Research

In breast cancer, there are two types of cancer cells, those that grow in response to estrogen, called Estrogen Receptor (ER) positive, or those that do not, called ER negative. ER+ breast cancer is typically treated with endocrine therapies and accounts for over three quarters of all breast cancers. In ER+ cancers, treatment typically includes blocking the estrogen receptor, in order to inhibit the growth of the cancer cells. A stapled peptide that inhibits the ER/coactivator interaction is discussed in the PepTalk. Research often looks at the estrogen receptor and ways to block its action. Peptides International carries several products for breast cancer research:

  • Estrogen Receptor Alpha, Mouse Anti Human (ESR1 Antibody)
    The binding of estrogen to ER induces a conformational change and triggers a cascade of events, including dissociation from heat shock proteins, receptor dimerization, phosphorylation and the association of the hormone activated receptor with specific regulatory elements in target genes. Most types of breast cancers have receptors for estrogen.
  • Estrogen Receptor Binding Site Associated Antigen 9 Human Recombinant (EBAG9)
    EBAG9 is a tumor-associated antigen that is expressed at high frequency in a variety of cancers, such as advanced breast and prostate cancers. While the EBAG9 acts to inhibit the growth of receptor-binding cells and induced apoptosis of immune cells, cancer cells may evade immune surveillance. Thus immunodetection of EBAG9 expression can be a negative prognostic indicator.
  • Estrogen Sulfotransferase Human Recombinant (SULT1E1)
    Decreased SULT1E1 expression is linked with estrogen-dependent endometrial carcinomas in breast cancer.
  • RAS-like, Estrogen-Regulated, Growth Inhibitor Human Recombinant (RERG)
    REGR is a novel ras-related, estrogen-regulated and growth-inhibitory gene in breast cancer.
  • LISA-101
    A fluorogenic Substrate for γ-Glutamyl Cyclotransferase (GGCT), which is upregulated in a wide range of cancers, including breast cancer.

 Additional products linked to estrogen:

Additional products linked to breast cancer:

 Contact us today if you need help locating an item, procuring a bulk quotation, or designing a custom peptide.

Product Spotlight for 8/14/2018

Diprotin B Belongs On Your "A-Team"

The dipeptidyl peptidases (DPP) are a subclass of exopeptidases, including some enzymes, that cleave either two or three amino acids from the end of a peptide or protein.1 Dipeptidyl aminopeptidase IV (DPPIV) is an intrinsic membrane protein that possesses a serine exopeptidase, which cleaves X-Pro dipeptides from the N-terminal (amine-terminal) end of peptides. This protease has a direct role in glucose metabolism by degrading incretins such as glucagon like peptide 1 (GLP-1).2 Although typically thought of in Diabetes research, some studies in cancer research have found DPPIV as an interesting target for the delivery of chemotherapeutic drugs3 and, moreover, measuring circulating DPPIV may also be useful in the early diagnosis of colorectal cancer.4 Peptides International is pleased to introduce the new product, Diprotin B, which is a tripeptide inhibitor of DPPIV.

Diprotin B: H-Val-Pro-Leu-OH
IDB-3982-PI (25mg and 100mg)

We also offer additional dipeptidyl peptidase products and can custom synthesize a custom product, if what you need is not commercially available. Contact us today for more information!

DPPIV inhibitor:

Diprotin A: H-Ile-Pro-Ile-OH
IDP-4132 (25mg and 100mg)
IDP-4132-v (0.5mg vial)

DPPII Inhibitor:

IDP-3655-PI (5mg)


Dipeptidyl-Peptidase 4 Human Recombinant
ENZ-375 (2µg, 10 µg, 1000µg)

View all dipeptidyl aminopeptidase products offered by Peptides International here on our website.



Product Spotlight for 7/31/18

When Dying is a Good Thing - Caspase Substrates and Inhibitors

Apoptosis, or programmed cell-death, is necessary for various vital cell-processes. A group of cysteine proteases, called caspases, are activated causing a “complex cascade of events” triggering apoptosis, typically by cleaving after an Asp residue in their substrates. However, either too little or too much cell-death is a factor in many conditions including cancer, neurodegenerative diseases, and autoimmune diseases. Not all types of cells die from certain stimuli, making induced apoptosis a possibility in the treatment of cancer.1 Many peptides used for apoptosis research revolve around the caspases. Not only are the caspases involved in cell-death, but some also have a role in inflammation. Proinflammatory caspases (table 1) are accompanied by a release of proinflammatory cytokines, interleukin-1β (IL-1β) and IL-18, and trigger a lytic form of cell death. Caspase effectors must be activated and are initiated by the caspase initiators, whereas, the caspase initiators are often autoactivated.2,3 Since cleavage of caspase substrates triggers apoptosis, it is useful to study the substrate cleavage site. Caspase substrates often have fluorescent groups in order to monitor this cleavage progress. Caspase inhibitors, on the other hand, prevent cell death by blocking the action of the caspases. Peptides International offers a wide array of caspase substrates and inhibitors and we can also prepare a custom product, tailored to your apoptosis research needs.

Table 1: Types of Caspases

Proinflammatory Caspases

Initiator Caspases

Effector Caspases

Caspase 1

Caspase 2

Caspase 3

Caspase 4

Caspase 8

Caspase 6

Caspase 5

Caspase 9

Caspase 7

Caspase 11

Caspase 10


Caspase 12




View our Caspase products flyer

View our Caspase products


  1. S. Elmore, Toxico Pathol. 25, 495 (2007).   
  2. J. Salgado, al., J. Peptide Sci. 8, 543 (2002).
  3. P.J. Baker & S.L. Masters, J. Biol Chem.,293(18), 7068 (2018).

Product Spotlight for 7/17/18 

For Oncology Research, RGD is the VIP

Even casual followers of this newsletter are probably aware that Peptides International has a comprehensive portfolio and extensive knowledge base of RGD (containing the Arg-Gly-Asp sequence) peptides.  These peptides have been long known to researchers as important tools for NCE (new chemical entities), drug design and development, preparation of radiolabeled derivatives for tumor targeting and imaging, and in novel biomaterials development.  They also play a special role in cell recognition, and related processes such as angiogenesis or endothelial apoptosis.  Design of drugs based on the RGD structure that inhibit the αvβ3 integrin function has been a focus of intense study for developing new treatments for cancer.1


For example, the cyclic pentapeptide cyclo(RGDf(NMe)V),2 CilengitideTM, an inhibitor of αvβ3 and αvβ5 integrin receptors, is being evaluated as a cancer drug3-5and is currently in phase III clinical trials for treatment of glioblastoma multiforme.6

Studies have also indicated that dendrimeric RGD conjugates may enhance the delivery of imaging agents that target carcinoma cells7,8and hold promise for siRNA delivery to solid tumors such as glioma.9

Peptides International has a large variety of RGD peptides for oncology research.  These include:

 Remember that if we don’t have it, we can make it!  Custom peptide synthesis is a specialty, including

  • Chemical route development
  • Process scale-up, multi-gram preparations, pilot-scale synthesis
  • Examples of analogs and derivatives:
    • Cyclic and linear RGD molecules
    • Multivalent peptides (dimeric to octameric)
    • Complex organic hybrids
    • Defined length PEG and bifunctional linkers
    • Biotin, fluorophores and chromophores
    • Chelating agents

Please contact us today for a quote or information on either our catalog or custom RGD products and services.


  1. H.M. Sheldrake and L.H. Patterson, Curr. Cancer Drug Targets, 4, 519 (2009). (Review)
  2. M. A. Dechantsreiter, E. Planker, B. Mathä, E. Lohof, G. Hölzemann, A. Jonczyk, S.L. Goodman, and H. Kessler, J. Med. Chem., 42, 3033 (1999).
  3. J.W. Smith, Curr. Opin. Investig. Drugs, 4, 741 (2003).
  4. D.A. Reardon, K.L. Fink, T. Mikkelsen, T.F. Cloughesy, A. O’Neill, S. Plotkin, M. Glantz, P. Ravin, J.J. Raizer, K.M. Rich, D. Schiff, W.R. Shapiro, S. Burdette-Radoux, E.J. Dropcho, S.M. Wittemer, J. Nippgen, M. Picard, and L.B. Nabors, J. Clin. Oncol., 26, 5610 (2008).
  5.  L. B. Nabors, T. Mikkelsen, T. Batchelor, G. Lesser, M. Rosenfeld, X. Ye, S. Piantadosi, J. Olson, S. Brem, and S. Grossman, J. Clin. Oncol., 27:15s, (suppl; abstr 2001) (2009).
  7. C.A. Boswell, P.K. Eck, C.A. Regino, M. Bernardo, K.J. Wong, D.E. Milenic, P.L. Choyke, and M.W. Brechbiel, Mol. Pharm., 5, 527 (2008).
  8. R. Shukla, T.P. Thomas, J. Peters, A. Kotlyar, A. Myc, and J.R. Baker Jr., Chem. Commun. (Camb.), 5739, DOI: 10.1039/b507350b (2005).
  9. C.L. Waite and C.M. Roth, Bioconjug. Chem., 2009 Sep 23. [Epub ahead of print], PMID: 19775120 (2009).

Product Spotlight for 6/25/18 

Rapamycin: A Veritable Swiss Army Knife for Researchers!

Rapamycin, or Sirolimus, is a metabolite from the bacteria Streptomyces hygroscopicus, and was first discovered in a soil sample of Easter Island. It takes its name from Rapa Nui, the Polynesian name for Easter Island, and -mycin, the suffix for aminoglycoside antibiotic compounds derived from a bacterium, such as Streptomyces. It has been found to have antifungal, anti-proliferative, and immunosuppressive properties. Rapamycin targets the mTOR (mammalian target of rapamycin) signaling pathway, which is in the family of phosphatidylinositol 3-kinase-related kinases and the master regulator of cell growth and metabolism. As such, it has implications in many diseases such as cancer, diabetes, genetic disorders, neurological diseases, and obesity. A primary use for Rapamycin is as an immunosuppressant in organ transplantation.1 Recently, it has also been seen to have a role in increasing lifespan. In mice, its longevity effects have been seen in various ways: in immune system changes, in cancer prevention, in neurological improvements, and more.2 Peptides International is pleased to introduce the versatile inhibitor, Rapamycin, to our product lineup.

100mg $70.00
1000mg $350.00


  1. J. Li et al., Cell Metab., 19(3), 373 (2014).
  2. D. Ehninger et al, Cell Mol Life Sci., 71(22), 4325 (2014).

Product Spotlight for 6/4/18 

Calcitonin Gene-Related Peptide (CGRP)

The PepTalk this week looks at a new Calcitonin Gene-Related Peptide (CGRP)-targeting drug that has been approved for the treatment of migraines. As a 37-amino acid neuropeptide that was first identified in 1982, CGRP belongs to the same family as adrenomedullin, amylin, and calcitonin. It is a hypotensive vasodilator and can be found circulating in both the nervous and endocrine systems. It exists in two isoforms, α and β, with α-CGRP (CGRP I) as the most studied form. We are pleased to offer several α-CGRP products for your research needs and should you require bulk or custom CGRP, please contact us today for a quotation.

Product Spotlight for 6/1/18        

A New Disulfide-Rich Peptide Toxin


Enterotoxin STh

As mentioned in our current PepTalk, there appears to be a strong implication between Multiple Sclerosis and a toxin produced by C. perfringens bacteria, primarily found in sheep. Many peptide toxins contain several disulfide bonds and can be tricky to synthesize. As experts in synthesizing peptides with multiple disulfide bonds, we are pleased to introduce a new peptide toxin, Enterotoxin STh. Enterotoxigenic E. coli are able to produce several toxic peptides which may cause acute diarrhea in humans and domestic animals. The E. coli heat-stable enterotoxin STh is composed of 19 amino acids containing three intramolecular disulfide bonds, which seem to be important for the correct conformation of the biologically active structure.

Enterotoxin STh

Disulfide Bonds: C6-C11, C7-C15, C10-C18

We also carry the related toxin:

Enterotoxin STp

View the rest of our peptides in our toxin collection here.

If a toxin of interest is not commercially available, we can also custom synthesize one for you. Please contact us today for a consultation or quote.

Product Spotlight for 5/15/18              


Products for Parkinson’s Disease Research

The PepTalk this week, “Thank Cod: There’s Something Fishy about the Brain-Gut Connection to Amyloids”, explores two interesting new studies in Parkinson’s disease research. So, we hereby present some products inspired by this PepTalk:

  • α Synuclein Human Recombinant PRO-393
  • Parkinson Disease Protein 7 Human Recombinant PRO-575
  • Parkinson Disease Protein 7, Mouse Anti Human ANT-317
  • Parvalbumin Human Recombinant PRO-004
  • Parvalbumin Rat Recombinant PRO-398

Additional Neuroscience Products of interest:

Read more in our Neuroscience Research Peptides Quick Reference.

If you need help locating an item or need a custom synthesis, please contact us, we would be happy to help!


Product Spotlight for 4/30/18              

Products for Neurodegenerative Disease Research

The first PepTalk for May covers two interesting studies on neurodegenerative diseases. Many neurodegenerative diseases are caused by the misfolding of several proteins, including Amyloid β-Protein, α-synuclein, and the huntingtin protein. Peptides International offers several products of interest in neurodegenerative disease research. Did you know that we offer discounts on bulk quantities? Please contact our friendly representatives for a bulk quotation today. Are you unable to find a product? We would be happy to help locate it or quote on a custom synthesis.

Amyloid β-Protein (Human, 1-42) (0.5 mg vial) PAM-4349-v

Amyloid β-Protein (1-42, O-acyl isopeptide)  PAB-AF683

Learn more about Amyloid β-Protein (1-42, O-acyl isopeptide) here.

Amyloid β-Protein (42-1) (0.1mg vial)  PAB-4420-s

Amyloid β-Protein (Human, 1-40) (HCl Form) (0.5 mg vial) PAB-4379-v

Amyloid β-Protein (40-1) (0.1mg vial)   PAB-4413-s

Amyloid β-Protein (Human, 1-40) Antiserum (50 ul vial)   NAP-14307-v

Anti-Amyloid β-Protein (1-40) (Human) Serum (50 ul)   NAY-81010-v

Amyloid β  (A4) Precursor Protein Human Recombinant   PRO-1080

α-Synuclein Human Recombinant  PRO-393

Parkinson Disease Protein 7 Human Recombinant   PRO-575

Parkinson Disease Protein 7, Mouse Anti Human   ANT-317


Our Amyloid β-Protein-related peptides brochure is found here:

Download our Neuroscience Research Peptides Quick Reference here:


Product Spotlight for 4/17/18                       

2 Types of Products for Type 2 Diabetes


Figure: Insulin hexamer

As referenced in our introduction in this issue of the PEPNET E-Newsletter, we are keeping our Product Spotlight shining on offerings for diabetes research. With that, we are proud to present twenty-three newly available antisera ELISA kits from the Yanahara Institute, via our partnership with the Peptide Institute! These items part of a larger portfolio of ELISA kits we recently added. Those related to diabetes research include:

There are also dozens of antisera available from both the Yanahara Institute and Peptide Institute as well, and they can be found listed in their own brochure.

In the second part of this entry we would like to enumerate the range of products found in the accompanying PepTalk from this week. They are:

Please contact our friendly customer service representatives for questions on these or any other item you may have for your research interests.

Product Spotlight for 4/3/18

New Products for Diabetes Research

With the World Health Organization (WHO) predicting that diabetes will be the seventh-leading cause of death worldwide by 2030, diabetes research is of increasing importance.1 This week we are pleased to present a selection of new products for diabetes and obesity research, offered by Peptides International:

  • Anti GIP (Rat) Serum NAY-8102-v
  • Anti GIP (18–42) (Rat) Serum NAY-8103-v
    Gastric inhibitory polypeptide (GIP) helps stimulate insulin secretion.
  • Insulin I (Rat, Mouse) PIN-4501-v
  • Insulin II (Rat, Mouse) PIN-4502-v
    Insulin, a peptide hormone secreted by the islet cells in the pancreas, is responsible for the body’s ability to effectively process sugar.  
  • Pancreastatin (Dephosphorylated Porcine) PAN-3978-PI
    Pancreastatin has been found to inhibit insulin secretion.

Diabetes Research Products related to this week’s PepTalk:

For further reading on Diabetes, we invite you to take a look at our newly updated Diabetes Research Products brochure. For discounts on bulk quantities, please inquire for a bulk quotation. Does your research require something not commercially available? Peptides International can custom synthesize a peptide to suit your needs.



Product Spotlight for 3/20/18

Kinases and the Treatment of Viral Infections

Enzymes are present in nearly every metabolic reaction in order to catalyze a specific biochemical reaction. Unlike other reaction catalysts, enzymes are highly specific due to their molecular shape. They alter the rate of reaction but not the reaction equilibrium. The kinases are enzymes that influence several activities within a cell including signaling, division, and metabolism. A kinase inhibitor blocks the kinase enzyme and can be useful in preventing cell actions in diseases like cancer since they impact the entire life cycle of the cell. Recently, kinase inhibitors have been explored in the treatment of viral infections which you can learn more about in the PepTalk. Peptides International carries several kinase-related products to meet your research needs. Not only can we provide catalog products, we can offer discounted, bulk quantities and custom synthesis.

Here is a selection of our kinase and viral products, as mentioned in the research in the accompanying PepTalk:


Product Spotlight for 2/28/18

Metabolic Syndrome

Metabolic syndrome is increasingly becoming a worldwide problem. Sedentary lifestyle and diet choices contribute to the disorder.1,2 Read more in the PepTalk this week, as we look at two recent studies into metabolic syndrome. Several peptide hormones are useful in the study of metabolism. Below is a selection of Peptides International products available for metabolism research. Should your project require bulk quantities or a custom product, please contact us for a quote.


  • Adiponectin, Mouse Anti Human
    ANT-232 (5µg, 20µg, 1000µg)
  • gAcrp30 Human (Globular Adiponectin Human Recombinant)
    CYT-615 (5µg, 25µg, 1000µg)





  • Retinoic Acid Receptor Responder 2 Human Recombinant
    PRO-788 5µg, 20µg, 1000µg)


  • FGF 21 Human
    CYT-474 (5µg, 20µg, 1000µg)


  • Ghrelin (Human)
    PGH-4372-s (0.1mg vial)
  • Ghrelin Human Recombinant
    HOR-294 (5µg, 25µg, 1000µg)




  • Fibronectin Type III Domain Containing 5 Human Recombinant, Yeast
    PRO-1663 (2µg, 10µg, 1000µg)        

Peptide-YY (PYY)

  • Peptide YY (Human, 3-36)
    PYY-4400-v (0.5 mg vial)
  • Peptide YY (Dog, Mouse, Porcine, Rat, 3-36)
    PYY-3726-PI (1mg, 5mg)

Plasminogen activator inhibitor-1

  • Plasminogen Activator Inhibitor-1 Human
    ENZ-356 (2µg, 10µg, 1000µg)
  • Plasminogen Activator Inhibitor-1 Human Recombinant
    ENZ-357 (5µg, 25µg, 1000µg)


  1. P. K. Santhekadura, et al., Biomed Pharmacother., 92, 826 (2017).


Product Spotlight for 2/6/18

Synthetic Inhibitors

Microbial inhibitors are produced by the actinomycetes bacteria. After protease inhibitors were discovered, it was found that microbial culture filtrates contained several enzyme inhibitors. In synthetic inhibitors, the compound is purified to contain one predominant analog, whereas the microbial versions may contain several compounds, including some metabolites.1,2 For instance, microbial leupeptin generally has 3 tautomeric isomers, while the synthetic product contains a single, purified isomer.

The new synthetic inhibitors are also ON SALE for 10% off until midnight, March 31, 2018!

For many other enzyme inhibitors, see our please see our brochure.

Inhibitor for Trypsin, u-PA, Papain, and Cathepsin A/B

Inhibitor for Trypsin, Plasmin, Papain, and Cathepsin

Pepstatin A
Inhibitor for Pepsin, Cathepsin D/E and Renin

Bestatin (Ubenimex)
Inhibitor of aminopeptidases, leucine aminopeptidase 3 (LAP3), and a potent, irreversible inhibitor of leukotriene A4 (LTA4) hydrolase

Peptides International carries a large selection of microbial products and additional synthetic inhibitors can be found here. Should you require larger quantities, bulk quantities are also available by quote.


  1. H. Umezawa, Antibiotics, 29(1), 97 (1976).
  2. H. Unezawa, Ann. Rev. Microbiol, 36, 75 (1982).


Product Spotlight for 2/6/18

Adipose Tissue Recombinant Proteins

The PepTalk this week is about irisin, a 121 amino acid residue polypeptide, which is able to convert white adipose tissue into brown adipose tissue. In humans, an overabundance of visceral white adipose tissue is present in obesity and type 2 diabetes whereas brown adipose tissue is beneficial. Peptides International is pleased to introduce several recombinant protein products for adipose tissue research, which also happen to be included in our current sale!

Adipose Differentiation-Related Protein Human Recombinant

Adiponectin, Mouse Anti Human

Angiopoietin-like Protein 4 Human Recombinant (Fasting- Induced Adipose Factor, ANGPTL4)


Complement Factor D Human Recombinant (Adipsin)

Fibronectin Type III Domain Containing 5 Human Recombinant, Yeast (Irisin, FNDC5)

Leptin Human Recombinant

Resistin Human

Resistin Mutant Human Recombinant

Resistin Human, His

Vaspin Human

Additional related products for type 2 diabetes research:

Glucagon-like Peptide 1 (1-37) (Human)
HOR-009 (recombinant)

Glucagon-like Peptide 1 (Human, 7-36 Amide) (0.5 mg vial)

PEX-3784-PI (synthetic)


Obestatin (Human)


Additional diabetes research products can be found here.

Do you need a custom peptide fragment of one of the proteins or a bulk quantity? Contact us today for a quotation.

Product Spotlight for 1/23/18

New Amyloid β-Protein Products


Peptides International is pleased to introduce some new Amyloid β-Protein peptide fragments. In Alzheimer’s Disease, plaques are thought to be formed primarily by fragments 1-40 and 1-42 of Amyloid β-Protein. However, the truncated version, 11-40, is also found in abundance in cerebrospinal fluid. This fragment is thought to have a higher binding affinity to Cu2+.1 Both truncated forms, Amyloid β-Protein (11-40) and [Pyr11]-Amyloid β-Protein (11-40), are found in Alzheimer’s Disease and Down’s Syndrome brains.2

Amyloid β-Protein (11-40) (Human)

[Pyr11]-Amyloid β-Protein (11-40) (Human)

Meanwhile, 26-O-acyl isoAβ1-42 is a water-soluble isopeptide that can be used to prepare Amyloid β-Protein (1-42) through a pH-induced acyl shift. By dissolving in water, an O->N migration occurs, generating native Aβ1-42 through an intramolecular acyl migration. The inclusion of the iso-depsi-peptide bond disrupts aggregation, alleviating a common difficulty when working with Amyloid β-Protein (1-42).3

Amyloid β-Protein (1-42, O-acyl isopeptide)

Our complete Amyloid β-Protein product line can be found here. We can also prepare custom Amyloid β-Protein fragments. Contact one of our peptide specialists today for a quotation.


  1. J.D. Barritt & J.H. Viles, J. Biol. Chem., 290, 27791 (2015). (Pharmacol.)
  2. K. Liu, et al., Acta Neuropathol., 112, 163 (2006). (Pharmacol.)
  3. T. Yoshiya, et al., Bioorg. Med. Chem. Lett., 24, 3861 (2014).


Product Spotlight for 1/8/18

Products for Pain Research

Managing pain is a daily task for many people. Because they change the way the brain and nervous system respond to pain, opioids are a commonly prescribed treatment. Unfortunately, opioids are highly addictive and often result in either prescription drug abuse or serve as a gateway to other drugs, such as heroin.1 Opioid overdose kills over 90 people a day in the United States and the problem is spreading worldwide. Given such issues, there is an increased urgency to find pain therapies that do not result in addiction. Opioids share a familiar N-terminal sequence which is known as the opioid motif, Tyr-Gly-Gly-Phe-(Met or Leu).2,3 The following are just some of the products that Peptides International carries for pain research:

  • Nociceptin, or Orphanin FQ, is a peptide comprised of 17 amino acids that is an agonist of the Opioid Receptor-Like-1 (ORL1) receptor and nociception is a nervous system response to pain or other harmful stimuli. Due to a lack of an N-terminal tyrosine, Nociceptin cannot act on classical opioid receptors, so the Nociceptin system opens potassium channels resulting in membrane hyperpolarization. When given nociception, rats experience either pronociceptive or antinociceptive effects, depending upon the dose.4
  • Dynorphin, β-endorphin, and the enkephalins activate opioid receptors.
  • The tachykinins, including Neurokinin and Substance P, are active in pain response.
  • The voltage-gated sodium channel, Nav1.7, is critical to pain sensation in mammals, as a result, blocking ion channels can help alleviate pain.5 We carry a large selection of ion channel blockers and toxins and our Peptide Toxins and Channel Blockers brochure can be found here.
  • The amino acids, Glutamate and aspartate, are considered brain excitatory neurotransmitters.
  • Oxytocin can play a role in treating addiction.6

Bulk discounts are available on larger quantities and we can also prepare a custom peptide to suit your research needs. Reach out today to obtain a quotation for your next project.

Read more about pain from our archives: Insensitivity to pain induced by a potent selective closed-state Nav1.7 inhibitor

Read our blog post, "Treating Addiction with Oxytocin".


  2. N.D. Volkow & F.S. Collins, N Engl J Med, 377(4), 391 (2017).
  4. J.Mika, et al., Neuropeptides, 45, 247 (2011). Retrieved from
  5. B. Halford, C&E News, 95(5), 40 (2017).
  6. M.T. Bowen & I.D. Neumann, Trends in Neurosciences, 40(12), 691 (2017).
  7. E.C. Emery et al., Expert Opinion on Therapeutic Targets, 20(8), 975 (2016).


Product Spotlight for 12/11/17

Alpha-2-Gliadin (57-89)

Celiac disease is a condition that occurs when the upper intestinal tract becomes inflamed, resulting in poor absorption of nutrients, and is thought to be triggered by the consumption of gluten proteins.2 Gluten is the main wheat flour protein, and is comprised mainly of gliadin and glutenin. Several regions of the N-terminal end of gliadin are immunologically active. A proline in the sequence makes hydrolysis sluggish, due its cyclical nature and secondary amine.1 A 33-residue peptide, derived from α2-gliadin (Alpha-2-Gliadin (57-89)),has been found to be resistant to enzymatic cleavage by intestinal peptidases, yet is highly immunoreactive, due to three overlapping T-cell epitopes.2 The high immunoreactivity of α2-Gliadin (57-89) makes it important in the study of celiac disease.

Peptides International is pleased to offer the following new product:

α-2-Gliadin (57-89)

We also carry:
Gliadin Wheat Recombinant

Do you need another fragment of gliadin, a labeled version, or something entirely different? As a leader in custom peptide synthesis, we can also custom prepare a peptide or related product to suit your research needs. Contact one of our specialists today!


  1. C.L. Gerez, et al., Letters in Applied Microbiology, 47, 427 (2008). doi:10.1111/j.1472-765X.2008.02448.x
  2. K. Schalk, et al., Scientific Reports, 7 (45092), (2017).


Product Spotlight for 11/28/17

New Bicyclic RGD Peptides Optimized for Click Chemistry

Figure 1: RGD-3879-PI



Figure 2: RGD-3993-PI

The Arginine-Glycine-Aspartic Acid (RGD) sequence is recognized by many integrins and is a cell attachment sequence for several proteins.1 In cancer tumor imaging, several radiolabeled, cyclic RGD peptides have been found to be useful in integrin αvβ3-targeting. Integrin αvβ3 binding affinity is also increased by using a bicyclic RGD peptide. 2-4

Moreover, Click chemistry is often used in the preparation of radiolabeled RGD peptides. Click chemistry is used to describe a class of efficient and selective reactions that can be used to join molecules together rapidly and in high yield. The addition of an azide (N3), in the presence of Cu(1), allows for the attachment of an alkyne-containing labeling molecule. On the other hand, the introduction of a maleimide (Mal) enables a reaction with thiols (-SH) to form stable bonds at neutral pH.

Peptides International is pleased to introduce two new bicyclic RGD peptides that are optimized for Click chemistry:



View the complete list of our RGD products.

Read more about our RGD peptides.

Read more about Click chemistry.

If you do not see what you are looking for, we can also prepare a custom peptide to meet your project specifications. Contact us today for a quote.


  1. C-C. Sun, X-J. Qu, & Z-H. Gao, American Journal of Therapeutics, 23, e198 (2016). Abstract retrieved from
  2. J. Shi, F. Wang, S. Liu, Biophysics Reports, 2(1), 1 (2016). Retrieved from
  3. S. Liu, Bioconjug Chem., 26(8),1413 (2015). Retrieved from
  4. S. Liu, Bioconjug Chem., 20(12),2199 (2010). Retrieved from


Product Spotlight for 11/8/17

Hunger Peptides

The PepTalk this week delves into some new research that looks into hunger and the interactions between gut hormones and the brain. Some peptides, such as bombesin, cholecystokinin (CCK), and ghrelin, alert the brain of hunger status. While others, including agouti-related peptide (AGRP), galanin, and Neuropeptide Y (NPY), increase the production of neurotransmitters.1 Meanwhile, appetite is decreased alongside levels of alpha-melanocyte stimulating hormone (α-MSH), cocaine and amphetamine-regulated transcript (CART), and neurotensin.2 Here is a selection of peptides for hunger research that are available from stock at Peptides International:

Agouti-Related Protein (Human, 86-132) (0.1mg vial)
Melanocortin Receptor-3/4 Antagonist; Appetite Boosting Peptide


Bombesin (0.5 mg vial)

Anti Bombesin Serum (50 ul)

CART (Human, 55-102) (0.1mg vial)

CCK-8 (sulfated)

CCK-8 (non-sulfated)
Additional CCK products can be found here.

Galanin (Human) (0.5 mg vial)

Galanin Prepropeptide Human Recombinant
Additional galanin products can be found here.

Ghrelin (Human)

Ghrelin (Human) (0.1mg vial), TFA salt
Additional ghrelin products can be found here

Leptin Human Recombinant

Anti-Leptin (Rat) Serum (50 ul)
Additional leptin products can be found here.

α-MSH (0.5 mg vial)
Additional MSH peptides can be found here.

NPY (Human, Rat) (0.1mg vial)

NPY (Human) Antiserum (50 ul vial)

Anti NPY (Human, Rat, Mouse) Serum (50 ul)
Additional Neuropeptide Y products can be found here.


Peptide YY (Human, 3-36) (0.5 mg vial)
Physiological Inhibitor for Food Intake / NPY Y2-Receptor Agonist

Even if we do not carry the peptide that you are looking for, we can custom synthesize one you need. Contact us today for a quote.

For more details on hunger peptides in relation to diabetes and obesity, we also have brochures available on the following topics:


  1. B. Perry & Y. Wang, Nutrition and Diabetes, 2, e26 (2012).
  2. J.P. Wilding, Diabetic Medicine, 19(8), 619 (2002).


Product Spotlight for 10/24/17

Microbial Products

Microbial inhibitors are produced by the actinomycetes bacteria. After protease inhibitors were discovered, it was found that microbial culture filtrates contained several enzyme inhibitors. Unlike a synthetic product, where the compound is purified to contain one predominant analog, microbial products may contain several compounds, including some metabolites. 1,2 For instance, microbial leupeptin generally has 3 tautomeric isomers (Figure 1). Peptides International carries a large selection of microbial products.  Of course, if there is a specific synthetic version you are looking for, please contact us for a custom peptide synthesis quotation.  Below are the microbial products that we offer:

Microbial Product Inhibitor for Trypsin, u-PA, Papain, and Cathepsin A/B
IAP-4062 (25 mg, 100 mg)
IAP-4062-v   (0.5 mg vial)

Arphamenine B 
Microbial Product Inhibitor for Aminopeptidase B
IAR-4149 (25 mg, 100 mg)
IAR-4149-v (0.5 mg vial)

Microbial Product Inhibitor for Chymotrypsin, Papain, and Cathepsin B/G
ICY-4063 (25 mg, 100 mg)
ICY-4063-v (0.5 mg vial)  

Ebelactone A
Microbial Product Inhibitor for Esterase, Lipase, and N-Formylmethionine Aminopeptidase
IEB-4155 (25 mg)  

Microbial Product Inhibitor for Elastase
IEL-4064 (25 mg, 100 mg)
IEL-4064-v (0.5 mg vial)  

Microbial Product Inhibitor for Proteasome
ILC-4368-v (0.2 mg vial)  

Microbial Product Inhibitor for Bovine Liver ß-Glucuronidase Glycosidase Inhibitors
CAR-24004-v (0.5 mg vial) 

Microbial Product Inhibitor for Aminopeptidase
ILH-4249-v (0.5 mg vial) 

Microbial Product Inhibitor for Trypsin, Plasmin, Papain, and Cathepsin
ILP-4041 (25 mg, 100 mg, 1 g)
ILP-4041-v (0.5 mg vial) 

Nojirimycin Bisulfite
Microbial Product Inhibitor for ß-Glucosidase (Apricot Emulsion) Glycosidase Inhibitors
CAR-24003-v (5 mg vial) 

Pepstatin A
Microbial Product Inhibitor for Pepsin, Cathepsin D/E and Renin
IPA-4397(25 mg, 100 mg)
IPA-4397-v (0.5 mg vial) 

Microbial Product Inhibitor for Thermolysin, Neutral Endopeptidase-2411 (ANP Degradation Enzyme), and Endothelin Converting Enzyme
IPO-4082-v(0.5 mg vial) 

Siastatin B
Microbial Product Inhibitor for Sialidase Glycosidase Inhibitors
CAR-24002-v (0.5 mg vial)

We also carry synthetic Bestatin (Ubenimex), an inhibitor of aminopeptidases, leucine aminopeptidase 3 (LAP3), and a potent, irreversible inhibitor of leukotriene A4 (LTA4) hydrolase:

UBX-3876-PI (HCl salt form)

Additional synthetic inhibitors can be found here.


  1. H. Umezawa, Antibiotics, 29(1), 97 (1976).
  2. H. Unezawa, Ann. Rev. Microbiol, 36, 75 (1982).


Product Spotlight for 10/10/17

Tools for Peptide Synthesis: Reagents

Although we are known for manufacturing peptides, we also carry many tools to help you with your peptide synthesis. We have already shone the Product Spotlight on a few of our tools for peptide synthesis: CLEAR-OX™, a tool for disulfide bond formation, our Clickables, building blocks for click chemistry, our amino acids and amino acid derivatives, and our resins for peptide synthesis. Now it is time to highlight our reagents for peptide synthesis. Whether your project requires an additive to prevent racemization, one to improve coupling during synthesis, or a reagent to incorporate a label or protecting group to your peptide, Peptides International has just what you need.

A Selection of Peptide Synthesis Additives:

DCCD (Crystalline Mass)
Synonyms: Dicyclohexylcarbodiimide, DCCI, DCC
Activates the carboxyl group for amino acid coupling in solid phase peptide synthesis (SPPS)

DCCD (Redistilled for Solid-Phase Synthesis)

WSCDŸHCl (Water-Soluble Carbodiimide Hydrochloride)

Synonyms: N-HBTU, 1-[bis(Dimethylamino)methylene]-1H-Benzotriazolium Hexafluorophosphate-3-Oxide

Synonym: 1H-Benzotriazolium-1-[bis(Dimethylamino)Methylene]-5-Chloro-Hexafluorophosphate-(1-),3-Oxide

Synonym: 1-Hydroxy-6-Chlorobenzotriazole
Efficient reagent to suppress racemization and to enhance coupling in peptide synthesis

OxymaPure® (Ethyl (Hydroxyimino)Cyanoacetate)
Considered as a replacement for HOBt, HOAT, HOOBt, HOPO, Cl-HOBT and other analogues. Suppresses racemization and enhances coupling efficiency.

Synonyms: Benzotriazol-1-yl-oxytripyrrolidinophosphonium hexafluorophosphate, (Benzotriazol-1-yloxy)tripyrrolidinophosphonium hexafluorophosphate

Synonym: 9-Fluorenylmethoxycarbonyl-N-Succinimide Ester
Used to add an Fmoc-protecting group to an amino group

Synonyms: N-Hydroxysuccinimide, NHS, 1-Hydroxy-2,5-pyrrolidinedione
Used to activate a carboxyl group in peptide synthesis

A Selection of Reagents for Peptide Labelling:

Used to add a Biotin to an amine group to prepare biotinylated peptides or proteins

Used to add a Biotin to an amine group to prepare biotinylated peptides or proteins

Synonym: (N-(2,4-Dintrophenyl)-ethylenediamine)

Not interested in synthesizing your own peptide or need a special derivative or resin? Contact Peptides International today and we can help with your next custom peptide synthesis project. We also have many in-stock catalog products that are ready to ship, search our online catalog here.


Product Spotlight for 10/3/17

Venom-derived Peptides


At the current time, there is great interest in researching peptides derived from natural sources. One popular source of inspiration is venom. Many species of animals use venoms as a form of protection and predation, including bees, cone snails, fish, frogs, lizards, sea anemone, shrew, snakes, spiders, and even platypus. Peptides International carries a long list of peptides derived from venoms. If a venom of interest is not commercially available, we can also custom synthesize one for you. Contact us today for a consultation or quote.

Some of our venom-derived peptides include:


Chlorotoxin (0.5 mg vial)

Conantokin G (0.5 mg vial)

ω-Conotoxin GVIA (0.5 mg vial)



GpTX-1 Toxin

Hirudin Recombinant

Huwentoxin-IV (0.1mg vial)

ProTx-1 (0.1mg vial)

ProTx-II (0.1mg vial)

Stichodactyla Toxin (ShK) (Amide)

View the rest of our venom-derived peptides in our toxin collection here.


Product Spotlight for 9/26/17

Fluorescence Resonance Energy Transfer Substrates (FRETS) are designed peptide substrates where there is a fluorophore (donor) and a quenching group (acceptor) on each side of a proteolytic site within a peptide. When an enzyme cleaves the peptide into two fragments, the fluorophore is no longer quenched and an increase in fluorescence occurs which is visible in the UV or visible spectrum. The fluorescence increase is proportional to the amount of peptide hydrolyzed. These substrates are useful for quantitatively detecting enzyme activities including proteolytic and inhibitive activity in vivo.

Some of our FRET Substrates include:


Fluorescence-Quenching Substrate for ADAM17 / TNF-α Converting Enzyme (TACE)



FRET Substrate for HIV Protease


FRETS-VWF73 (0.1mg vial)

Fluorescence quenching substrate for ADAMTS-13


MOCAc-Pro-Leu-Gly-Leu-A2pr(Dnp)-Ala-Arg-NH2 (1mg vial)

Fluorescence-Quenching Substrate for Matrix Metalloproteinases



For a complete list of FRET substrates, we invite you to take a look at our FRET substrate brochure here or our product listing here.

We also carry a library of FRETS, located here on the Peptides International website.

Making your own FRET substrates? Read about fluorescent labeling reagents here and view our complete list of available reagents here.

If you need to design a substrate for your newly discovered enzyme or application, then please

contact our specialists to begin your Substrates by DesignTM project today.


Product Spotlight for 9/19/17

Amyloid β-Protein has long been implicated in the development of Alzheimer’s Disease, although its modus operandi has not yet been fully identified. Peptides International carries several fragments of Amyloid β-Protein, including the heavily researched Amyloid β-Protein (1-42). We can also custom synthesize a fragment to meet your research needs.

Amyloid ß-Protein (Human, 1-42) (0.5 mg vial)

Amyloid ß-Protein (42-1) (0.1mg vial)

Amyloid ß-Protein (Human, 1-40) (HCl Form) (0.5 mg vial)

Amyloid ß-Protein (Human, 1-40) (TFA Form) (0.5 mg vial)

ß-Sheet Breaker Peptide iAß5 (5 mg vial)

ß-Sheet Breaker Peptide iAß5 (Bulk)

You can explore our collection of Amyloid β-Protein fragments here:

Our Amyloid β-Protein-related peptides brochure is found here:


Product Spotlight for 9/12/17


Mosquitoes, including the species Aedes aegypti, Aedes albopictus, Anopheles, and Culex pipiens, spread several bacterial, viral, and parasitic illnesses including Chikungunya virus, dengue fever, malaria, West Nile Virus (WNV), Zika Virus (ZKV), and several forms of encephalitis.Peptides International has a large selection of products to aid in mosquito-borne illness research.  We can also custom synthesize a protein fragment to meet your specifications.

We are pleased to introduce the following new products:

Chikungunya E2 Recombinant

Dengue-2 Envelope Hydrophobic Domain Recombinant

Dengue Antigen for Rapid Test Recombinant

Dengue Multiple Epitopes 10 Recombinant

Dengue Multiple Epitopes 13 Recombinant

Malaria Vivax MSP1 Recombinant

Malaria Falciparum MSP1 Recombinant

Zika NS1 Paired Antibody/Mouse Anti Zika NS1 Paired

Zika Envelope Domain-III Recombinant

Zika Envelope N-Terminal Recombinant


We also carry the products for the following illnesses:

Contact us today to learn more about a product or service.


  2. S. Weaver, C. Charlier, N. Vasilakis, & M. Lecuit., Annu. Rev. Med., (6).1–6 (2018). [Review in advance]. Retrieved from

Further reading:


Product Spotlight for 8/30/17


When the body synthesizes insulin, C-Peptide has an important role in linking the A and B chains together for proper folding and disulfide bond formation. It is released at an equimolar concentration with insulin.1 C-Peptide may also play a role in gestational diabetes; where serum C-Peptide levels seem to be linked to risk of developing pre-diabetes and diabetes.2

C-Peptide (Human)

[Tyr0]-C-Peptide (Human)


Anti C-Peptide I (Rat) Serum (50 ul)


Anti C-Peptide II (Rat) Serum (50 ul)


Insulin (Human) (0.1mg vial)


View our selection of C-Peptides on our website here.

Other insulin products can be located here.

Learn more about Diabetes Peptides that are offered by Peptides International here.

Diabetes Related Peptides can be found here.


  1. J. Wahren, et al., Am J Physiol Endocrinol Metab, 278, (2000) E759. Retrieved from
  1. P. Yin, et al., Journal of Diabetes and Its Complications, 0(0), 2017. [Article in print] Retrieved from


Product Spotlight for 8/21/17

Teduglutide is a 33-residue peptide derivative of glucagon-like peptide-2 (GLP-2). GLP-2 has been modified with the substitution of a glycine in place of the alanine in the second position. This modification allows for increased half-life and resistance to in vivo degradation. A recombinant form is used as a long-term treatment of short bowel syndrome (SBS) that requires intravenous nutrition, or parenteral support. Teduglutide helps SBS by increasing fluid and nutrient absorption in the small intestine, eliminating the need for parenteral support.1 We now offer synthetic, research grade teduglutide as a part of Peptides International’s collection of Research Exemption Peptides.





  1. K. McKeage, Clin Drug Investig., 35(5), 335 (2015). doi: 10.1007/s40261-015-0286-6.


*Please note: This product is offered and sold solely for uses reasonably related to the development and submission of information under a Federal law which regulates the manufacture, use or sale of drugs (the “Bolar Exemption”). Peptides International cannot be made liable for any infringement of intellectual property rights. It is the sole and only responsibility of the purchaser or user of this product to comply with the relevant national rules and regulations.


Product Spotlight for 8/15/17


Peptides International is pleased to introduce the elastase substrate, H-Ala-Ala-Ala-pNA, a chromogenic substrate for porcine pancreatic elastase and for astacin, a crayfish zinc-endopeptidase.1, 2,4 It can also can bind non-productively to the active site of Tripeptidyl-peptidase II (TPP II), a subtilisin-like serine protease.3 Many other elastase substrates and inhibitors are also available from Peptides International for your research interests.

Elastase Substrates

H-Ala-Ala-Ala-pNA • HCl
SAA-3752-PI (250mg and 1g)

SAA-3071-v (5mg vial
SAA-3071 (100mg and 1g)

SAP-3118 (0.1mg and 1mg)

SAP-3666-PI (5mg and 25mg)

Elastase Inhibitors

Elafin (Human)
PEL-4243-v (25mg vial)

IEL-4064-v (0.5mg)
IEL-4064 (25mg and 100mg)

ICL-4146 (25mg and 100mg)

View all elastase products offered by Peptides International here.


    1. J.Bieth, et al., Biochem. Med., 11, 350 (1974).
    2. J.Bieth and C.G.Wermuth, Biochem. Biophys. Res. Commun., 53, 383 (1973).
    3. S. Eklund, et al., Biochimica et Biophysica Acta, 1824, 561 (2012).


et al., Biol. Chem. Hoppe-Seyler



      , 385 (1991).



Product Spotlight for 8/8/17


In the PepTalk this week, we take a look at some new research on aging. Some peptides from the research covered that are interesting in the study of aging include:

Ghrelin increases during fasting and may play a role in longevity via caloric restriction. It may also lower oxidative stress due to the aging process.1

  • Ghrelin (Human) (0.1mg vial)     
  • Ghrelin (Human) (1 and 5 mg)                         

Read more about Ghrelin here.
Explore our Ghrelin products here.

Fibroblast Growth Factor-23 (FGF23) is acted upon by Klotho and may play a role in aging.1

  • FGF23 Human                            

Explore our FGF products here.

Insulin-Like Growth Factor (IGF-1) and Growth Hormone (GH) levels decline during aging, like ghrelin, although their role in the aging process is not yet understood. 1

  • IGF-1 Human                                           

Explore our IGF-1 and related products here.
Explore our growth hormone and related products here.

Neuropeptide Y (NPY) may play a role in autophagy in the hypothalamus.1

Explore our Neuropeptide Y and related products here.

Sirtuin is controlled by nicotinamide adenine dinucleotide (NAD) and regulates metabolism. It plays a role in aging due to caloric restriction by possibly affecting NPY.1

  • Sirtuin-1 recombinant                                          
  • Sirtuin-2 recombinant                                          

Take a look at our Sirtuin product brochure here.
Explore our Sirtuin products here.


  1. M. Amitani et al., Int. J. Mol. Sci., 18, 1511 (2017). doi:10.3390/ijms18071511


Product Spotlight for 8/1/17

Did you know that Peptides International carries polyamino acids and polypeptides? A common use for Poly-L-Lysine is to increase cell adhesion when using glass slides or other glassware. As a cationic polymer, Poly-L-Lysine binds to any negatively charged peptides and proteins, improving attraction to a coated glass surface.1 We offer Poly-L-Lysine (MW > 12,000) in both HCl and HBr salt forms. Meanwhile, polypeptides may be used for NMR and conformational analysis to study of hydrogen bonds and helical formations of collagen.2 The sequence, Pro-Hyp-Gly, is found in fibrous collagen, and (Pro-Hyp-Gly)10 is considered to be one of the most stable prototypes of a triple helix.3 Several of the polypeptides we carry are also enzyme inhibitors.

Our Products:

Poly-L-Lysine Hydrobromide                                      OKK-3056

Poly-L-Lysine Hydrochloride                                      OKK-3075

Poly-L-Glutamic Acid Sodium Salt                             OEE-3063

(Pro-Pro-Gly)5 • 4 H2O                                                OPG-4005

Proline Hydroxylase Inhibitor

 (Pro-Pro-Gly)10 • 9 H2O                                              OPG-4006

Inhibitor of Collagenase, MMP, and α-Tumor Necrosis Factor

 (Pro-Hyp-Gly)5 • 10 H2O                                             OPG-4032

Inhibitor for Prolyl Endopeptidase

 (Pro-Hyp-Gly)10 • 20 H2O                                            OPG-4033

Collagenase Inhibitor

 View our brochure on Popular Polypeptides & Collagen-like Helical Model Peptides here.


  1. D. Mazia, et al., J Cell Biol., 66(1), 198 (1975).
  2. S. Sakakibara, et al., Biochim. Biophys. Acta, 303, 198 (1973). (Original)
  3. T. Kishimoto, et al., Biopolymers, 79, 163 (2005). doi:10.1002/bip.2034

Additional references:

D.A. Slatter, C.A. Miles, and A.J. Bailey, J. Mol. Biol., 329, 175 (2003).
R. Berisio, V. Granata, L. Vitagliano, and A. Zagari, Biopolymers, 73, 682 (2004).


Product Spotlight for 7/25/17

As experts in custom peptide synthesis, we are certainly familiar with the tools that you will need to carry out your own peptide synthesis. Recently we spotlighted a few of these tools: CLEAR-OX™, for post-cleavage disulfide bond formation, The ClickablesTM products for click chemistry, and our amino acids and amino acid derivatives. Now the focus turns to our selection of resins for peptide and protein synthesis. And if your project should require larger quantities, contact us today for a bulk quotation!

Fmoc-protected Amino Acid Resins

Unsubstituted Resins for Solid Phase Synthesis

Chlorotrityl Resins: For preparation of acids, alcohols, thiols, or amines

CLEAR™ Resins: Cross -Linked Ethoxylate Acrylate Resins with desirable solvation properties and ease of use. Learn more about our ClearTM Resins here.

Resins for Protein Ligation

TentaGel Resins: a gelatinous resin constructed with a backbone of low crosslinked polystyrene grafted with polyoxyethylene (polyethylene glycol).



Product Spotlight for 7/18/17

Immunohistochemistry for alpha-synuclein showing positive staining (brown) of an intraneural Lewy-body in the Substantia nigra in Parkinson's disease. Image source: By Marvin 101 (Own work) [CC BY-SA 3.0 (], via Wikimedia Commons. Creator does not endorse content.

One of the hallmarks of Parkinson’s disease is the presence of α-synuclein protein.  The function of α-synuclein is unknown but it is a major component of Lewy bodies, or protein aggregates, in the brain.1 Errors in its folding may play a role in loss of cells responsible for dopamine production.Not only do we offer an array of α-synuclein related products, we can custom synthesize a specific fragment to meet your research needs.

α-Synuclein Human Recombinant                                                     Product Code: PRO-393

α-Synuclein A30P Human Recombinant                                           Product Code: PRO-158

α-Synuclein A53T Human Recombinant                                            Product Code: PRO-159

α-Synuclein A30P/A53T Human Recombinant                                  Product Code: PRO-160

α-Synuclein NACP112 Human Recombinant                                     Product Code: PRO-162

α-Synuclein 1-60 Human Recombinant                                             Product Code: PRO-165

α-Synuclein 61-140 Human Recombinant                                         Product Code: PRO-163

α-Synuclein 96-140 Human Recombinant                                         Product Code: PRO-164

β-Synuclein Human Recombinant                                                     Product Code: PRO-394

γ-Synuclein Human Recombinant                                                      Product Code: PRO-395

α-Synuclein Mouse Recombinant                                                      Product Code: PRO-858

α-Synuclein Delta-NAC Human Recombinant                                   Product Code: PRO-161

β-Synuclein, Polyclonal Rabbit Anti-Human Antibody                       Product Code: ANT-454

γ-Synuclein, Polyclonal Rabbit Anti-Human Antibody                       Product Code: ANT-455

α-Synuclein, Mouse Anti Human                                                        Product Code: ANT-315


Click here to view a list of all of our α-Synuclein products on our website.


  2. A. Recchia et al., The FASEB Journal, 18(6), 617 (2004). doi: 10.1096/fj.03-0338rev


Product Spotlight for 7/11/17


Peptides International offers a variety of research exemption peptides. Among them is linaclotide, a peptide for the treatment of bowel disorders.   It is a 14-residue peptide with three disulfide bonds derived from heat stable enterotoxin.1 Linaclotide is a guanylate cyclase C agonist (GCCA) and has a structure similar to guanylin and uroguanylin.2 Activation of this receptor leads an increase of intracellular cGMP which results in chloride, bicarbonate and water release into the lumen of the large intestine by way of the Cystic Fibrosis Transmembrane Conductance Regulator (CFTR) ion channel. When not carefully controlled, this results in diarrhea.3 Like the recently approved plecanatide,4 it is an orally delivered treatment for chronic constipation. We are pleased present research grade linaclotide for your drug discovery inquiries.




Disulfide bonds: Cys1-Cys6, Cys2-Cys10, Cys5-Cys13


  1. Love et al., Am. J. Health-System Pharmacy, 71, 1081 (2014).  DOI 10.2146/ajhp130575
  2. P. Layer & V. Stangellini. Aliment Pharmacol Ther., 39(4), 371 (2014). Retrieved from
  3. Weiglmeier et al., Toxins, 2, 2213 (2010). doi:10.3390/toxins2092213
  4. Shailubhai, K et al., Dig Dis Sci., 58(9), 2580 (2013). doi: 10.1007/s10620-013-2684-z


Product Spotlight for 6/27/17

Not only do we manufacture catalog and custom peptides, we also carry the tools to assist you with your own peptide synthesis. Recently we spotlighted a few of these peptide synthesis tools: CLEAR-OX™, for post-cleavage disulfide bond formation, and The Clickables products for click chemistry. This time we highlight our amino acids and amino acid derivatives. We carry a range of protected, unprotected, and unusual amino acids. Are you looking for larger quantities? Contact us today for a bulk quotation.

Boc-protected Amino Acid Derivatives

Fmoc-protected Amino Acid Derivatives

Z-Protected Amino Acids

Unprotected L- and D- Amino Acids

Other Building Blocks


Product Spotlight for 6/20/17

Product Spotlight – Cholecystokinin

 A Gut Check: CCK Peptides

Cholecystokinin (CCK) is a regulatory peptide which is one of the gastrointestinal hormones. In mammals, it is in the same family as gastrin and they also share the same receptor, CCK2. Most CCK is expressed in the brain, where CCK-8 is the most abundant fragment expressed in neurons. In human plasma, CCK-33 is the most abundant fragment found. It is found in many forms and with both sulfated and non-sulfated tyrosine. Originally only known for its functions in digestion, including gallbladder emptying and enzyme secretion by the pancreas, it is now known to also function as a neurotransmitter, a growth factor, a cardiac marker of heart failure, an anti-inflammatory cytokine, a natriuretic kidney peptide, and possibly a spermatozoon fertility factor.1 We carry a variety of CCK products and can custom synthesize any others that you may need.

CCK-33 (Human)

CCK-33 (Porcine)

CCK-33 (porcine) antiserum

CCK-8 (sulfated)

CCK-8 (non-sulfated)

anti-CCK-8 (Human, Rat) serum

CCK-4 (25mg, 100mg)

CCK-4 (0.5mg vial)


  1. J. F. Rehfeld, Front. Endocrinology, 8, 1 (2017). (mini review)


Product Spotlight for 6/13/17

Glucagon-like Peptide 1 (GLP-1) is a gut hormone released in response to food intake that helps regulate carbohydrate metabolism, insulin production, and appetite. Recently, two groups of scientists have been able to generate structures of the GLP-1 receptor bound to an agonist.1,2 We carry a selection of GLP-1 peptides and GLP-1 agonists, including some research exemption peptides, such as exenatide (exendin-4), semaglutide, liraglutide, and more. We also carry a large selection of related feeding regulatory peptides. Need something not commercially available? We can also custom synthesize a peptide to suit your needs.

Some of our GLP-1 and related products:

Glucagon-Like Peptide 1 (Human, 1-37)

Glucagon-Like Peptide 1 (Human, 7-36 amide)

Glucagon-Like Peptide 1 (Human, 7-36 amide)

Glucagon-Like Peptide 1 (7-37)

Oxyntomodulin, Glucagon-37 (Human, Mouse, Rat)

Oxyntomodulin activates GLP1-R and GCGR. It is an inhibitor of gastric acid secretion and pancreatic enzyme secretion and has been shown to reduce food intake and increase energy expenditure in humans.

PEX-3784-PI                        Exendin-4

Exendin-4 is a GLP-1 receptor agonist

Other related Feeding Regulatory Peptides:

PAP-4362-s                        Apelin-36 (Human)

NES-3863-PI                        Nesfatin

PGH-3741-PI                        Ghrelin (Human)

PGL-4098-s                        Glucagon (Human)

PIN-4088-s                        Insulin (Human)

CYT-270                        Insulin (Human) (recombinant)

For a complete list of GLP-1 products, click here.

Read more about Glucagon-Like Peptide 1 Receptor Agonists for Type II Diabetes here.

Read more about our Research Exemption Peptides here.

For a list of Feeding Regulatory Peptides, click here.


  1. Y. Zhang et al., Nature, (2017 online). doi:10.1038/nature22394 Retrieved from
  2. A. Jazayeri et al., Nature, (2017 online). doi:10.1038/nature22800 Retrieved from


Product Spotlight for 6/6/17

CLEAR-OX™ is a useful polymer-supported reagent for post-cleavage disulfide bond formation. It is especially useful for sensitive residues, such as Met, Trp, and Tyr. Oxidation takes place in higher concentrations than a solution method, using fewer reagents, typically only takes 1-2 hours for completion, and results in higher yields and higher purity than conventional folding methods. Jingwen Zhang, et al., of Amgen, used CLEAR-OX™ under acidic conditions (pH <5.5), in the folding of human Hepcidin, a peptide with four disulfide bonds, with great results.1

Learn more about CLEAR-OX™ here.

Polymer-Supported Oxidant for Disulfide Bond Formation CLEAR™ Polymer-Supported Oxidant for the Facile Formation of Disulfide-Bridged Peptides


  1. J. Zhang, S. Diamond, T. Arvedson, B.J. Sasu, and L.P. Miranda. Biopolymers, 94, 257 (2010). doi:10.1002/bip.21383


Product Spotlight for 5/31/17

As distributors of Quanta BioDesign products, we are proud to introduce some new discrete polyethylene glycol (dPEG®) products. We now offer DBCO-dPEG® linkers and labels for strain-promoted azide-alkyne cycloaddition (SPAAC) reactions. The DBCO allows for orthogonality in biological matrices and a fast reaction rate toward the azide functionality as well as the ability to bioconjugate chromophores, radionuclides, or biotin. We are also pleased to introduce DOTA- dPEG® bifunctional chelators. Adding a hydrophilic linker between the DOTA and the biologic can influence the pharmacokinetics and biodistribution of the conjugate. Furthermore, they also improve solubility and aggregation. Learn more about dPEG® derivatives here.

DBCO-dPEG® Linkers and Labels:



DBCO-TFP ester

DBCO-dPEG®4-TFP ester

DBCO-dPEG®12-TFP ester

DBCO-dPEG®24-TFP ester










DOTA- dPEG® Bifunctional Chelators:

DOTA-tris(TBE)-amido-dPEG®4-TFP ester

DOTA-tris(TBE)-amido-dPEG®12-TFP ester

DOTA-tris(TBE)-amido-dPEG®24-TFP ester

DOTA-tris(acid)-amido-dPEG®4-TFP ester

DOTA-tris(acid)-amido-dPEG®12-TFP ester

DOTA-tris(acid)-amido-dPEG®24-TFP ester













Product Spotlight for 5/23/17

Peptide FK18 is derived from the active binding domain of human basic fibroblast growth factor (bFGF). Researchers at Shanghai Jiao Tong University have found that it offers a neuroprotective effect that holds promise for vison and life-threatening diseases due to ischemic neuronal injury. It has been seen to offer both in vivo and in vitro neuroprotection.1

Peptide FK18


  1. S. Xiong, et al., Neurochemistry International (2017).


Product Spotlight for 5/16/17

We are pleased to introduce a new dipeptide, Fmoc-Gly-Pro-OH. This dipeptide can be useful for fragment condensation. Its use minimizes des-Gly and des-Pro impurities that can occur during synthesis. It can also be used in solid phase peptide synthesis to minimize diketopiperazine (DKP) formation when this is expected.




Product Spotlight for 5/9/17

Vastly Important Vasopressin

Vasopressin, or [Arg8]-vasopressin, is a nine-residue peptide with a disulfide bond. It is biologically active in the central nervous system (CNS) and in the periphery. It has been found to regulate water in the body and plays a role in blood pressure.1 Most recently, its social behavior influence has been examined, including its role in autism. Researchers at Stanford University have shown a link between low [Arg8]-vasopressin levels and decreased empathy, which contributes to difficulties in social interactions.2

Vasopressin / [Arg8]-Vasopressin


  1. R.E. Brinton & B.S. McEwen, The Journal of Neuroscience, 9(3), 752 (1989).
  2. D.S. Carson et al., PLoS ONE, 10(7), e0132224 (2015).


Product Spotlight for 5/2/17

Scientists have recently shown that CD32a can be a biomarker for HIV-1 reservoir cells.1   CD32a, or Fc-gamma-RIIa, is a class of leukocyte IgG receptors (FcγR). The FcγR serve as a cellular and humoral branches of the immune system. CD32a is found in nearly all myeloid cells and may induce phagocytosis and degranulation. It is essential for the induction of efficient effector functions.2

FCGR2A Human

View our collection of HIV-1 products here.


  1. B. Descours, et al., Nature, 543, 564, (2017).
  2. N.M. van Sorge, W-L. van der Pol, & J.G.J. van de Winkel, Tissue Antigens, 61, 189 (2003).



Product Spotlight for 4/25/17

Inhibiting Hypertension: Ubenimex (Bestatin), HCl Salt form

We are pleased to introduce our synthetic bestatin, also known as Ubenimex. Bestatin is an inhibitor of aminopeptidases, leucine aminopeptidase 3 (LAP3), and a potent, irreversible inhibitor of leukotriene A4 (LTA4) hydrolase.1 Like leupeptin, the microbial form of bestatin is produced by the actinomycetes bacteria. Umezawa, et al, discovered bestatin by screening actinomycetes culture filtrates. They discovered that it was an inhibitor of leucine aminopeptidase and a specific inhibitor of aminopeptidase B. They also found it did not inhibit aminopeptidase A, chymotrypsin, elastase, papain, pepsin, trypsin, or thermolysin.2

Ubenimex (Bestatin) HCl Salt

Ubenimex (Bestatin)


  1. L. Örning, G. Krivi and F. A. Fitzpatrick, The Journal of Biological Chemistry, 266,1375,(1991).
  2. H. Umezawa, et al., Antibiotics, 29(1), 97 (1976).


Product Spotlight for 4/18/17

Follow the Light: Substrates Containing Abz/EDDnp

We have several substrates containing the FRET pair, Abz (2-aminobenzoic acid) and EDDnp (N-(2,4-Dintrophenyl)-ethylenediamine). The Abz is the fluorescent donor and the EDDnp is the quencher. The Abz/EDDnp pair has a good energy overlap as well as a pH-insensitive high efficiency of fluorescence quenching. Upon cleavage of a peptide bond within the substrate, fluorescence is released.1 Along with our catalog substrates, we can custom synthesize an Abz/EDDnp substrate.

Substrate for Human Kallikrein 6 (hK6)

Fluorescence-Quenching Substrate for Human Neutrophil Elastase

Fluorescence-Quenching Substrate for Human Neutrophil Cathepsin G

Substrate for Cellular prion protein (PrPc)

Fluorescence-Quenching Substrate for Human Neutrophil Proteinase 3

EDDnp (N-(2,4-Dintrophenyl)-ethylenediamine)


  1. A.K. Carmona, M.A. Juliano, & L. Juliano, Anais da Academia Brasileira de Ciências, 81(3), 381 (2009).


Product Spotlight for 4/11/17

What's the Buzz About Bee Venom Peptides?

Bee venom contains several peptides, including Apamin, Mast Cell Degranulating Peptide or MCD Peptide, Melittin, Tertiapin, and Tertiapin Q. Apamin is an 18-residue peptide with two disulfide bonds found in small amounts in bee venom and derives its name from Apis, the genus for bee. It acts upon the central nervous system (CNS) and was found to induce convulsions, spasms, and involuntary jerks. It is a small conductance Ca2+-activated K+ channel blocker.1 MCD peptide, on the other hand, is a 22-residue peptide with two disulfide bonds also found in small amounts in bee venom. It has a potent anti-inflammatory effect and also acts on the CNS by blocking a class of voltage-gated potassium channels. Melittin comprises the majority of bee venom, at almost 50 percent of the peptide content, and is a 26-residue peptide. It does not have any anti-inflammatory effect, however, it does play a role in histamine release from mast cells.2 Tertiapin, and its derivative tertiapin Q, are 21-residue peptides and non-toxic, potent blockers of GIRK1/4 current and ROMK1 channels. They do not inhibit the IRK1 channel. The addition of a glutamine in place of methionine improves stability and binding of Tertiapin Q.3 Bee venom phospholipase A2 (bvPLA2) is an enzyme that can hydrolyze several lipids through interfacial binding. It is a suitable membrane anchor and a tumor-antigen vector for cell-based vaccines.4

We offer these bee venom products and can custom synthesize melittin or any other peptides as well:

Apamin (0.5 mg vial)
(Disulfide bonds between Cys1-Cys11 and Cys3-Cys15) 

Mast Cell Degranulating Peptide MCD Peptide (0.5 mg vial)
(Disulfide bonds between Cys3-Cys15 and Cys5-Cys19)

Tertiapin (0.1 mg vial)
(Disulfide bonds between Cys3-Cys14 and Cys5-Cys18)

Tertiapin Q
(Disulfide bonds between Cys3-Cys14, Cys5-Cys18)
Phospholipase A2 P00630 Bee Venom Protein Recombinant


  1. E. Haberman, Pharmacol. Ther., 25, 255 (1984). (Review)
  2. M.R. Ziai, S. Russek, H.-C. Wang, B. Beer, and A.J. Blume, J. Pharm. Pharmacol., 42, 457 (1990). (Review)
  3. W. Jin, A.M. Klem, J.H. Lewis, and Z. Lu, Biochemistry, 38, 14294 (1999).
  4. C. Almunia et al., PLOS ONE, 8(6), e67645 (2013).


Product Spotlight for 4/4/17

IL-1β and TNF-α

Recently, Stender et al., showed the mechanisms behind cytokine-mediated endocrine resistance in breast cancer cells. The resistance was caused by the pro-inflammatory cytokines, Interleukin 1 beta (IL-1β) and Tumor Necrosis Factor-alpha (TNF-α).1 The interleukins are a type of cytokine produced by white cells as signaling molecules, while the tumor necrosis factors are a type of cytokine that can cause cell death, or apoptosis.

Learn more about cytokines here.

See our complete list of available cytokines here and related PepTalk here.

IL-1β, Human

IL-1β, Human, HEK

TNF-α Human


1.     J.D. Stender et al., Molecular Cell, 65, 1122 (2017).


Product Spotlight for 3/28/17

Peptides International now has a synthetic Leupeptin available for your research needs.  Synthetic Leupeptin tends to have increased potency, possibly due to a lack of competing side products. Leupeptin is a dipeptide aldehyde that is an endopeptidase inhibitor for serine and cysteine proteinase.  The microbial form is produced by the actinomycetes bacteria and inhibits trypsin, plasmin, cathepsin B, kallkrein, and papain.1 There have been two peptides isolated from the actinomycetes bacteria, both in propionyl and acetyl forms.2 The acetyl form is the form that is named leupeptin, where the propionyl form is often called Propionyl-leupeptin.


Leupeptin (Synthetic) Hemisulfate Monohydrate
Acetyl-L-leucyl-L-leucyl-L-argininal hemisulfate monohydrate; Ac-LLR-CHO

Click here for our complete list of Leupeptin products.


  1. M. Tashiro, H-D. Klink, & R. Rott., J. gen. Virol., 68, 2039 (1987).
  2. K. Kawamura, S-I. Kondo, K. Maeda, & H. Umezawa, Chem. Pharm. Bul., 17(9), 1902 (1969).


Product Spotlight for 3/21/17

Peptides International now offers the Zika Envelope full-length protein. It is a flavivirus that is transmitted by mosquitoes. Like other flaviviruses, Zika virus is enveloped, icosahedral and has a nonsegmented, single-stranded, positive-sense RNA genome. The flavivirus envelope protein is responsible for virus entry into cells.1 The protein is fused to a 6xHis tag at the C-terminus.  

Zika Envelope Full Length


  1. L. Dai, et al., Cell Host & Microbe, 19, 696 (2016).


Product Spotlight for 3/14/17

Numerous combinations of dimeric RGD vector peptide derivatives with different bifunctional chelators and radionuclides, followed by the evaluation of the resulting radiotracers'  biological properties (eg., 1-4), led to the selection of an optimal product, 99mTc-3P-RGD2.

This radiotracer, after successful animal studies(eg., 5-7), has been used in extensive clinical trials as an excellent SPECT modality probe for noninvasive monitoring of tumor growth or treatment efficacy(eg., 89-12).

Read more here.

H-dPEG®4-Glu[dPEG®4(cyclo (Arg-Gly-Asp-D-Phe-Lys))]2



  1. L. Wang, et al., Mol. Pharm., 1, 231 (2008).
  2. Z. Liu, et al., Eur J Nucl Med Mol Imaging, 36, 947 (2009).
  3. J. Shi, et al., Bioconjugate Chem, 20, 750 (2009).
  4. S. Liu, Bioconjugate Chem., 26, 1413 (2015).
  5. T. Fu, et al., Cancer Biother. Radiopharm., 29(9), 351 (2014).
  6. S. Ji, et al., J Pharmacol Exp Ther., 346(2), 251 (2013).
  7. B. Yan, et al., J Radioanal Nucl Chem., 304(3), 1171 (2015).
  8. Q. Ma, et al., J Nucl Med., 55(1), 1538 (2014).
  9. Z. Zhu, et al., J Nucl Med., 53(5), 716 (2012).
  10. D. Zhao, et al., J Nucl Med., 3(12),1872 (2012).
  11. B. Chen, et al., Int J Clin Exp Pathol., 8(12), 16064 (2015).
  12. J. Fu, et al., Mol Clin Oncol., 6, 197 (2017).


Product Spotlight for 3/7/17

Mambalgin-1 is a peptide derived from the Black Mamba (Dendroaspis polylepis polylepis) snake venom. It is a potent, rapid, reversible inhibitor that targets acid-sensing ion-channels (ASICs), which are thought to be pain pathways. It has the ability to decrease inflammatory pain with a potency similar to morphine by targeting both central neurons and nociceptors.1 Mambalgin-1 is 57-residue peptide with four disulfide bonds.

Mambalgin-1 Black Mamba

Disulfide Bonds: Cys3-Cys19, Cys12-Cys37, Cys41-Cys49, and Cys50-Cys55

Mambalgin-1 (0.1mg vial)


  1. S. Diochot, et al., Nature, 490, 552 (2012).


Product Spotlight for 2/28/17

Hepcidin is a peptide hormone that is secreted mainly by the liver.  It is processed and secreted as 25 residue peptide (Hepcidin-25), although some shorter variants are detected in the urine as well: Hepcidin-20 (C-terminal 20 residues) and Hepcidin-22 (C-terminal 22 residues).1  Hepcidin initially was discovered for its antimicrobial activity and its role in iron regulation was later discovered.  Hepcidin’s primary role is regulating iron homeostasis.2  Hepcidin regulates iron by binding to ferroportin, the iron exporter, leading to its internalization and degradation. In turn, release of iron by macrophages is inhibited and iron uptake is decreased in the gut.4  The N-terminal 9 residues seem to be sufficient for stimulating ferroportin internalization and designed and improved analogs of this N-terminal fragment were active in mouse models of iron-overload disorder.Hepcidin levels may also be a useful marker of iron deficiency anemia and inflammation.4 more about Hepcidin here.

Some of our Hepcidin products include:

Hepcidin / Leap-1 (Human)
Liver-Specific Antimicrobial Peptide / Iron-Regulatory Hormone: Asp-Thr-His-Phe-Pro-Ile-Cys-Ile-Phe-Cys-Cys-Gly-Cys- Cys-His-Arg-Ser-Lys-Cys-Gly-Met-Cys-Cys-Lys-Thr
Disulfide bonds: Cys7-Cys23, Cys10-Cys13, Cys11-Cys19, and Cys14- Cys22

Hepcidin-24 (Human)
H-Thr-His-Phe-Pro-Ile-Cys-Ile-Phe-Cys-Cys-Gly-Cys-Cys- His-Arg-Ser-Lys-Cys-Gly-Met-Cys-Cys-Lys-Thr-OH; des-Asp1-Hepcidin-24
Disulfide bonds: Cys6- Cys22, Cys9-Cys12, Cys10- Cys18, and Cys13-Cys21

Hepcidin-22 (Human)
Disulfide bonds: Cys4-Cys20, Cys7-Cys10, Cys8-Cys16, and Cys11-Cys19

Hepcidin-20 (Human)
Disulfide bonds: Cys2-Cys23, Cys10-Cys13, Cys11-Cys19, and Cys14-Cys22

Hepcidin-9 (Mouse)

Human Hepcidin IDx™ ELISA

Hepcidin-Murine Compete™ ELISA Kit

For a complete list of our hepcidin products, click here.


  1. C.H. Park, E.V. Valore, A.J. Waring, T. Ganz, Hepcidin, a urinary antimicrobial peptide synthesized in the liver., J Biol Chem, 276, 7806 (2001). Hepcidin, a urinary antimicrobial peptide synthesized in the liver.
  2. T. Ganz, E. Nemeth. Hepcidin and iron homeostasis. Biochim.Biophys.Acta, 1823(9):1434 (2012).
  3. E. Ramos, P. Ruchala P, Goodnough JB, Kautz L, Preza GC, Nemeth E, Ganz T. Minihepcidins prevent iron overload in a hepcidin-deficient mouse model of severe hemochromatosis. Blood, 120, 3829 (2012). PMID 22990014 DOI: 10.1182/blood-2012-07-440743
  4. N.L. Blanchette, D.H. Manz, F. Torti, S. Torti., Expert Rev Hematol, 9 (2), 169 (2016). Retrieved from


Product Spotlight for 2/21/17

Apelin-36 is an endogenous ligand for the apelin receptor, APJ, an orphan G protein-coupled receptor (GPCR).1 The apelin peptides are involved in cardiovascular and metabolic activities and were thought to be modulated by APJ. Recently, a team of NGM Biopharmaceuticals and MedImmune researchers, led by Hadas Galon-Tilleman, has determined that apelin-36 has the ability to modulate metabolism and blood glucose independent of canonical APJ signaling. They found that although both apelin-36 and apelin-13 activate APJ equally, apelin-36 has the ability to lower blood glucose levels and body weight as well as improve lipid levels and glucose tolerance. By selectively pegylating with a 30kD Peg derivative, they were also able to create a longer-acting peptide, which does not lower blood pressure because it is less potent in activating APJ, however, it significantly lowered blood glucose levels and increased glucose tolerance in mice.2 This is good news since some diabetes management drugs have had concerns about dangerously lowering blood pressure.

Below are our apelin catalog products and of course we also have the ability to deliver custom peptide synthesis derivatives to meet your specific needs.

Apelin-36 (Human) (0.1mg vial)

Apelin-36 (Human, 1-16 Amide) (01mg vial)
SCNH2 (Selective Apelin-36 Cutting and Amidation Peptide)

[Pyr1]-Apelin-13 (Human, Bovine) (0.5 mg vial)


  1. Anne-Marie O'Carroll, et al., J Endocrinol, 219, R13 (2013). Retrieved from
  2. Hadas Galon-Tilleman, et al., JBC, 292, 1925 (2016). Retrieved from


Product Spotlight for 2/14/17

The use of native chemical ligation in peptide synthesis has enabled the easier synthesis of longer peptides while still maintaining the peptide backbone. We are pleased to announce a new product useful for peptide ligation, Mob-S-Mercaptoproprionic acid (or S-Mob-Mpa). It is suited for the Fmoc-synthesis strategy and is orthogonal to cysteine protected with the trityl group. Cleavage conditions for S-Mob-Mpa are similar to those used for Cys(Mob) deprotection. You can remove the Mob group with TFA/TFMSA /anisole + 5% EDT.

Mob-S-Mercaptoproprionic acid



Product Spotlight for 2/7/17

Polypeptides have been found to play many roles in beer brewing, from their effects on foam, to beer quality, body, flavor, and color. Proteinase A, which is produced during fermentation by yeast cells, can have a negative impact on the stability of a beer’s foam. Proteinase A is responsible for digesting foam-active proteins during prolonged storage. Beer brewers can turn to the Fluorescence-Quenching Substrate for Proteinase A, MOCAc-Ala-Pro-Ala-Lys-Phe-Phe-Arg-Leu-Lys(Dnp)-NH2, to monitor proteinase A levels. The substrate is highly sensitive to proteinase A.1   Other strategies to improve beer foam stability during storage include adding other enzymes that are not destroyed during pasteurization, such as papain.2

MOCAc-Ala-Pro-Ala-Lys-Phe-Phe-Arg-Leu-Lys(Dnp)-NH2 (1 mg vial)

Fluorescence-Quenching Substrate for Proteinase A / Pepsin

Suc-Arg-Pro-Phe-His-Leu-Leu-Val-Tyr-MCA (1 mg vial)
Substrate for Proteinase A and Renin

  1. H. Kondo, H. Yomo, S. Furukubo, N. Fukui, and K. Nakatani, J. Inst. Brew., 105(5), 293 (1999).
  2. I.H.L. Ormrod, E.L. Lalor, and F.R. Sharpe, J. Inst. Brew., 97, 441 (1991).

Product Spotlight for 1/31/17

We are proud to introduce research-grade semaglutide*. Semaglutide is a glucagon-like peptide (GLP-1) analogue and a GLP-1 receptor agonist. Not only does it have a half-life of up to one week, it has been used in type 2 diabetes research for its ability to stimulate insulin production while suppressing glucagon secretion in a glucose-dependent manner. Semaglutide has an increased albumin affinity and exhibits a three-fold decrease in GLP-1 receptor affinity when compared to liraglutide.1 Recent studies in patients with type 2 diabetes suggest that semaglutide may also have an improved cardiovascular outcome in those patients who are at risk for a cardiac event.2            

  1. J. Lau, et al., J. Med. Chem., 58, 7370 (2015). Retrieved from
  2. S.P. Marso, et al., N. Engl. J. Med., 375, 1834 (2016). Retrieved from


*Please note: This product is offered and sold solely for uses reasonably related to the development and submission of information under a Federal law which regulates the manufacture, use or sale of drugs (the “Bolar Exemption”). Peptides International cannot be made liable for any infringement of intellectual property rights. It is the sole and only responsibility of the purchaser or user of this product to comply with the relevant national rules and regulations.  


Product Spotlight for 1/24/17


Are you looking for a custom synthesis? Peptides International has the expertise to provide exceptionally high quality custom peptide synthesis products to meet your research needs. We aim to deliver quality, cost-effective, custom products in a timely manner. With decades of experience in the industry, we are experts in the synthesis of the most complex and difficult peptides including multiple disulfide bond peptides and peptide macrocycles. We can also provide custom peptidomimetics, peptide derivatives (including labeled peptides), multi-step organic synthesis, post-translational modification, peptide-protein conjugations, unusual amino acid derivatives, custom analytical services, and more. Contact us today to discuss your next custom project. We strive to deliver a price quotation, in most cases, within 24 hours.

Read more about our custom synthesis services here.


Product Spotlight for 1/17/17

The RGD peptides, named for the Arg-Gly-Asp (RGD) in their sequence, are recognized by many of the integrins. These integrins are called the RGD-binding integrins. This sequence is a cell attachment site for many proteins and are involved in many cell processes including cell proliferation and differentiation. Many strategies for fighting disease target these RGD-binding integrins because they are easily accessible and inhibited by peptides, peptidomimetics, and monoclonal antibodies.1




Some of our RGD products:

Fibronectin Active Fragment (RGDS)
PFA-4171, PFA-4171-v (0.5 mg vial)
Arg-Gly-Asp-Ser ● ½AcOH ● 2H2O

αvβ3 Integrin Binding RGD Peptide RGD Tumor Targeting Peptide

RGD Tumor Targeting Peptide (linker additions via Cys)

View the complete list of our RGD products

Read more about our RGD peptides


  1. C.-C. Sun, X.-J. Qu, & Z.-H. Gao, American Journal of Therapeutics, 23, e198 (2016). Abstract retrieved from


Product Spotlight for 1/10/17

Nav1.7 Blocking Peptides

In our recent report with researchers at Janssen Research and Development, tarantula venom-derived ProTx-II was used as scaffold for designing potent and selective closed-state Nav1.7 blocking peptide. During the course of this work, from a library of more than 1500 peptides, a unique peptide with optimal properties was identified. The peptide JNJ63955918, containing an N-terminal Gly-Pro addition coupled with Trp7 to Gln and Trp30 to Leu, resulted in a product which had both excellent pharmacological properties in terms of selectivity over other Nav1.x subtypes, as well as greatly improved manufacturing yields.  The general solution structure of the peptide JNJ63955928 overall is the same as ProTx-II. Furthermore, the peptide induces pharmacological insensitivity to pain that closely recapitulates the Nav1.7 phenotype seen in mice and humans.


ProTx-II (PTX-4450-s)


ProTx-II (0.1 mg vial)

(M.W. 3826.60) C168H250N46O41S8
(Disulfide Bonds between Cys2- Cys16, Cys9- Cys21, and Cys15- Cys25)
Na+ Channel (Especially Nav1.7) / Ca2+ Channel Blocker (Gating Modifier)
Synthetic Product

R.E. Middleton, et al,, Biochemistry, 41,14734 (2002).(Original)
J.J. Smith, et al,, J. Biol. Chem., 282, 12687 (2007). (Pharmacol.; Novel Toxin Binding Site Coupled to NaV Activation)
B.T. Priest, et al,, Toxicon, 49,194 (2007). (Review)

GpTX-1 Toxin
(M.W. 4073.90) C176H271N53O45S7
Tarantula Venom Peptide Antagonist; Possible Therapeutic Target for Pain Treatment
34 amino acid peptide with selective antagonist activity for Nav1.7 channel

J. Murray, et al., Engineering Potent and Selective Analogues of GpTx-1, a Tarantula Venom Peptide Antagonist of the Nav1.7 Sodium Channel. Med. Chem., 58, 2299 (2015).

Huwentoxin- IV (0.1 mg vial)
HWTX-IV, Glu-Cys-Leu-Glu-Ile-Phe-Lys-Ala-Cys-Asn-Pro-Ser-Asn-Asp-Gln-Cys-Cys-Lys-Ser-Ser-Lys-Leu-Val-Cys-Ser-Arg-Lys-Thr-Arg-Trp-Cys-Lys-Tyr-Gln-Ile-NH2
(M.W. 4106.80) C174H278N52O51S6
(Disulfide bonds between Cys2- Cys17, Cys9- Cys24, and Cys16- Cys31)
Neuronal Tetrodotoxin-Sensitive Na+- Channel Blocker

K. Peng, et al., J. Biol. Chem., 277, 47564 (2002). (Original)
J. Diao, et al., Toxicon, 42, 715 (2003). (cDNA Seq)
Y. Xiao, et al., J. Biol. Chem., 283, 27300 (2008). (Pharmacol.)
Y. Xiao, et al., Toxicon, 51, 230 (2008). (Pharmacol.)

Mambalgin-1 (0.1 mg vial)
(Black Mamba, Dendrooaspis polylepis)
(M.W. 6554.5) C272H429N85O84S10 [1401381-87-0]
(Disulfide bonds Cys3-Cys19, Cys12-Cys37, Cys41-Cys49, and Cys50-Cys55)

S. Diochot, et al., Nature, 490, 552 (2012).
M. Pan, et al., Chem. Commun., 50, 5837 (2014). (NMR Structure & S-S Bond)

Psalmotoxin 1 (0.1 mg vial)

(M.W. 4689.4) C200H312N62O57S6
(Disulfide bonds between Cys3-Cys18, Cys10-Cys23, and Cys17-Cys33)
Selective Blocker for Acid-Sensitive Ion Channel, ASIC1a

P. Escoubas, et al., J. Biol. Chem., 275, 25116 (2000). (Original; Primary Structure & ASIC Blocking Selectivity)
P. Escoubas, et al., Protein Sci., 12, 1332 (2003). (Three-dimensional Solution Structure)
X. Chen, et al. J. Gen. Physiol., 127, 267 (2006). (Pharmacol.; State-Dependent Function)

(M.W. 2966.45) C123H201N37O40S4
(Disulfide bonds between Cys5-Cys16 and Cys10-Cys23)
A Potent Activator of TRPV1 Capsaicin Receptor, Inducing Intense Pain.

S. Yang,et al., Nature Communications, 6, 8297 (2015).


M. Flinspach, Q. Xu, A.D. Piekarz, R. Fellows, R. Hagan, A. Gibbs, Y. Liu, R.A. Neff, J. Freedman, W.A. Eckert, M. Zhou,
R. Bonesteel, M.W. Pennington, K.A. Eddinger, T.L. Yaksh, M. Hunter, R.V. Swanson, and A.D. Wickenden,
Scientific Reports, 7, 39662 (2017). DOI: 10.1038/srep39662


Product Spotlight for 1/3/17


Many bacterial infections are becoming resistant to traditional antibiotic treatments, so the hunt is on for new treatments. Many peptides have been identified that have antimicrobial activity.  One such recently reported peptide is Lugdunin, a “macrocyclic thiazolidine peptide antibiotic”.  Lugdunin is produced by human nasal Staphylococcus lugdunensis strains causing inhibition of the colonization of Staphylococcus aureus.  S. aureus, also known as “staph” bacteria, is often implicated in many human infections. Lugdunin is a cyclic peptide containing an unusual thiazolidine heterocycle and the five amino acids: D-valine, L-tryptophan, D-leucine, L-valine, and D-valine.  According to Zipperer, et al., it has a potent antimicrobial activity against many Gram-positive bacteria as well as against multiple drug resistant organisms (MDROs), methicillin-resistant S. aureus (MRSA)andvancomycin-resistant Enterococcus. Although bactericidal against S. aureus, it did not cause lysis of primary human neutrophils or erythrocytes and did not demonstrate considerable inhibition of metabolic activity of the human monocytic cell line HL60.  Current research suggests that it may be difficult for bacteria to develop a resistance to Lugdunin.1



  1. A. Zipperer, et al., Nature, 50, 511 (2016). Retrieved from




Product Spotlight for 12/22/16

Neuropeptides and Appetite

Appetite control is important in the management of type 2 diabetes and obesity. Several neuropeptides play a role in appetite regulation. Some neuropeptides originate in the gastrointestinal system and are sent to the brain alerting hunger level status, such as bombesin, cholecystokinin (CCK), and ghrelin. Others circulate in the blood, such as insulin and leptin. When neurotransmitters identify decreased levels of circulating neuropeptides, they increase production of hypothalamic neurotransmitters such as the agouti-related peptide (AGRP), galanin, and Neuropeptide Y (NPY).1 Meanwhile, decreased levels of alpha-melanocyte stimulating hormone (α-MSH), cocaine and amphetamine-regulated transcript (CART), and neurotensin decrease appetite.2 Peptides International has a large selection of appetite-regulating peptides available from stock and can synthesize any custom peptide or peptidomimetic to suit your research needs.

Insulin PIN-4088-s

  • Click here to view our Feeding Regulatory Peptides brochure.
  • Click here to view our Insulin brochure.
  • Click here to view our Ghrelin, Obestatin, and Nesfatin brochure.
  • Click here to view our Diabetes brochure.


  1. B. Perry and Y. Wang, Nutrition and Diabetes, 2, e26 (2012).
  2. J.P. Wilding, Diabetic Medicine, 19(8), 619 (2002).     


Product Spotlight for 11/29/16

Voltage-Gated Ion Channels

Shk and Kaliotoxin

ShK (A) and Kaliotoxin (B)

Voltage-gated ion channels are transmembrane proteins that form channels through the cell membrane that allow ions to traverse this barrier. There are specialized channels for the major physiological ions, Na+, K+, Ca2+, and Cl-.  Their opening is controlled by membrane potential, hence the term voltage-gated ion channels, versus others that are ligand gated for example. There have been numerous genes discovered that are associated with each channel.1 Targeting the voltage-gated ion channels has been successful in treatments of cancer, autoimmune diseases, Multiple Sclerosis, Parkinson’s disease, and more.  In fact, many peptide toxins are channel blockers.  One example, ShK, a 35-residue peptide derived from the sea anemone, Stichodactyla helianthus, is a highly-selective and potent Kv1.3 potassium-channel blocker and has been found to be useful in the treatment of autoimmune diseases.2   In addition to a selection of in-stock ion channel-blocking peptides, Peptides International also has the expertise to custom synthesize high-quality, difficult, disulfide-rich and complex peptides to suit your project needs.

 Click here for our Peptide Toxins and Channel Blockers brochure.

Click here for a useful database on Potassium Channel Toxins from scorpion venom.


    1. D. Purves, et al., (ed.) Neuroscience (5th ed.), Sunderland, MA: Sinauer Associates. (2012).
    2. M.W. Pennington, et al., Marine Drugs, 13(1), 529 (2015). Retrieved from


Product Spotlight from 11/29/16


Matrix metalloproteases (MMPs), also known as matrixins, are a large family of zinc-dependent enzymes, or metalloproteases, that regulate cell-matrix composition.1 Not only can MMPs degrade the extracellular matrix, they have been found to be able to modify several non-matrix substrates, including cytokines and chemokines. These proteases have also been found to influence many inflammatory processes.4 MMPs have been recognized as possible targets for many types of pathologies, including tumor angiogenesis, inflammation, osteoarthritis, neuroinflammation, and more.3 MMP-2 and MMP-9, two collagenases, are the most abundant MMPs present in the brain.2 In many cases, propeptide processing can be blocked by inhibiting zinc proteases, and this provides an effective, and potentially selective, approach for controlling peptide production and influencing signal transduction.

View more information about our MMP substrates and inhibitors

View our MMP products


  1. E. Biljana, et al., Journal of Cell and Animal Biology, 5(7), 113 (2011).
  2. M.E. De Stefano and M.T. Herrero, Progress in Neurobiology, (2016). Retrieved from
  3. M.W. Ndinguri, et al., Molecules, 2012(17), 14230 (2012).
  4.  P. Van Lint and C. Libert, Journal of Leukocyte Biology, 82, 1375 (2007).


Product Spotlight from 11/22/16

Dying in Order to Live: Apoptosis-Related Peptides

Apoptosis, or programmed cell-death, is necessary for various vital cell-processes. A group of cysteine proteases, called caspases, are activated causing a “complex cascade of events” triggering apoptosis. However, either too little or too much cell-death is a factor in many conditions including cancer, neurodegenerative diseases, and autoimmune diseases. Not all types of cells die from certain stimuli, making induced apoptosis a possibility in the treatment of cancer1. Many peptides used for apoptosis research revolve around the caspases. The RGD peptides are also found to inhibit tumor metastasis and induce endothelial cell apoptosis and are thought to be due to integrin-ligand interaction inhibition2.

View our Caspase products flyer

View our Caspase products

View our RGD products brochure


  1. S. Elmore, Toxico Pathol. 25, 495 (2007). Retrieved from
  2. J. Salgado, et al., J. Peptide Sci. 8, 543 (2002). Retrieved from


Product Spotlight from 11/15/16

Peptide Macrocycles - Lord of the Rings

Peptide macrocycles are ring-shaped molecules that have a wide application range from drug discovery to nanomaterials. By nature, they are resistant to proteolytic degradation making them good for biomolecular interactions at protein-protein interfaces.2 In addition, their capacity for fine-molecular tuning makes them excellent therapeutic agents. Some common macrocycles include calcitonin, octreotide, and cyclosporine A. However, using traditional synthetic methods, peptide macrocycles have been difficult to synthesize due to entropically unfavorable conditions.1 Ring size is also important when considering an appropriate synthesis strategy. Fortunately, there have been many developments in the synthesis of peptide macrocycles.

Because of their therapeutic viability, despite notoriously difficult synthetic methods, peptide macrocycles are expected to experience exponential growth. White and Yudin, 2011, have written a synopsis on contemporary strategies in peptide macrocyclization. They found that anchoring the linear precursor peptide to an insoluble polymer allows for a more efficient cyclization and simpler purification. An efficient cyclization depends upon the linear precursor to have its reactive ends in spatial proximity prior to ring closure. One method to decrease end-to-end distance is introducing a cis-amide bond in the center of the peptide chain, creating something similar to a β-turn. Metal ions have also been used to facilitate peptide macrocyclization1. Ye and co-authors propose that peptide macrocyclization is promoted by alkali metals which bind the carbonyl and amide groups at the peptide c-terminus.3 Another strategy explored is using an imidazole which is thought to attack the thioester, forming a reactive intermediate that is later intercepted by another nucleophile.1

In 2015, Yudin explores additional methods of synthesis as well as challenges to the properties of macrocycles. Some macrocycles have the ability to undergo interconversion between multiple conformations. This can be challenging if the predominant conformation is not the reactive one. Another issue is that there is a correlation between intramolecular bonding and cell-permeability. This presents a choice: either target cellular permeability or reactivity.4

Most recently, Frost, Scully, and Yudin, 2016, have explored preparing peptide macrocycles using an oxadiazole linker grafted into the peptide backbone. They present a macrocyclization reaction between a linear peptide, an aldehyde, and (N-isocyanoamino)triphenylphosphorane, which is completed in a single step. By utilizing a unique hydrogen-bond network, their new linkage allows for a well-conserved conformational geometry and stabilizes the turn motifs which in turn promotes passive membrane permeability. This method is conducive to customization. Changing the peptidic component results in macrocycles of different lengths. By varying the aldehyde component, other functional groups can be introduced into the macrocycle.2

Some Examples of Macrocyclic Peptides offered by PI:


cyclo (Arg-Gly-Glu-D-Phe-Lys)

(M.W. 617.71) C28H43N9O7

Cyclorasin 9A5
(M.W. 1586.86) C75H108N25O13F
Inhibitor of K-Ras and Lung Cancer Growth. Activates Apoptosis

P. Upadhyay, et al., Angew. Chem. Int. Ed., 54, 1 (2015).

Cyclorasin 9A54
(M.W. 1644.95) C79H115N25O12F2

P. Upadhyay, et al., Angew. Chem. Int. Ed., 54, 1 (2015).

Cyclorasin 12A
(M.W. 1528.78) C71H102N27O11F

P. Upadhyay, et al., Angew. Chem. Int. Ed., 54, 1 (2015) (Sup. Inf.)

(M.W. 1019.24) C49H66N10O10S2     [83150-76-9]
(Disulfide bond between Cys2-Cys7)
Somatostatin Analog

Please note: This product is offered and sold solely for uses reasonably related to the development and submission of information under a Federal law which regulates the manufacture, use or sale of drugs (the “ Bolar Exemption”). Peptides International cannot be made liable for any infringement of intellectual property rights. It is the sole and only responsibility of the purchaser or user of this product to comply with the relevant national rules and regulations.


  1. White and Yudin, Nature Chemistry (Review article), 3, 509 (2011). Retrieved from
  2. Frost, Scully, and Yudin, Nature Chemistry, Advance Online Publication, (2016). Retrieved from
  3. Ye, Yh., Gao, Xm., Liu, M. et al., Lett Pept Sci, 10, 571, (2003). doi:10.1007/BF02442590 Retrieved from
  4. Yudin, A.K., Chem Sci, 6, 30 (2015).


Product Spotlight from 11/8/16

GLP is a VIP

The glucagon family of neuropeptides are important in both diabetes and obesity research. In the body, the pancreatic islet α-cells liberate glucagon, a 29 amino acid peptide, from proglucagon. Glucagon is a hormone that helps regulate glucose and ketone production in the liver.1 In the gut, prohormone convertase cleaves glucagon-like peptide-1 (GLP-1), GLP-2, oxyntomodulin, and glicentin from proglucagon. The cleavage results in several different fragments, with GLP-1 (7-37) and GLP-1 (7-36) amide being the most predominant GLP-1 analogs found. Dipeptidylpeptidase-4 (DPP-IV) also plays a role by cleaving GLP fragments. Fasting GLP-1 levels are low; however, after a meal there is a 2-3-fold increase in GLP-1 fragments.2

4132 Diprotin A

Glucagon-like peptide-1 and related-incretin mimetics (liraglutide, exenatide) and dipeptidylpeptidase-4 (DPP-IV) inhibitors (sitagliptin) are drugs which help control post-meal glucagon levels, for the treatment of type 2 diabetes. There have been recent concerns about these drugs being associated with an increase in pancreatic and other cancers.   Researchers at McGill University and the Jewish General Hospital in Canada evaluated a population based cohort study of UK women with type 2 diabetes who were treated with GLP-1 analogues or DPP-IV inhibitors to determine if there is an increased risk of breast cancer associated with the use of the GLP-1 analogues. Although there was an uptick of diagnoses in the two to four-year range of use, the risk returned to close to null with continued analogue use. In the end, they found that there was no overall increased risk of breast cancer in the GLP-1 analogue users.3

Learn more about our Glucagon and GLP products.
Learn more about our DPP-IV inhibitor, Diprotin A.
Learn more about our Diabetes related peptides.


  1. Diabetes Education Online. Retrieved from
  2. Pujadas & Drucker. Endocrine Reviews. (2016). Retrieved from
  3. Hicks, et al., The British Medical Journal. (2016). Retrieved from and


Product Spotlight from 11/1/16

Alzheimer’s Disease

As the sixth leading cause of death in the United States, Alzheimer’s disease, a chronic neurodegenerative disease, affects more than 5 million people in the United States alone. It is estimated that Alzheimer’s disease and other dementias will cost $236 million in medical care in 2016. Alzheimer’s disease is a progressive brain disorder that causes problems with memory, thinking, and behavior. Extracellular amyloid plaques, caused by the Amyloid β-Protein, and intracellular neurofibrillary tangles are hallmark features of the disease.1

The buildup of plaques in the brain from Amyloid β-Protein cause inflammation and neurodegeneration. Recently, P. Bhattarai and his team in Dresden, Germany, have discovered that, in zebrafish, Interleukin-4 (IL-4) is activated by neurons in response to Amyloid β-Protein, resulting in increased neuron proliferation. This discovery can lead to further research in treating human neural degradation due to Alzheimer’s.2 If scientists can figure out how to activate IL-4 in humans, the lost neurons can possibly be replaced.

In families where early-onset Alzheimer’s disease is prevalent, it is thought that a mutation in the PSEN1 gene creates a defective presenilin-1 protein. This in turn causes a disruption in the function of the γ-secretase complex.3 DAPT is an inhibitor of presenilin-dependent γ-secretase which has been shown to block Amyloid β-Protein production in neuronal cultures.4



  2. Bhattarai et al., Cell Reports, 17, 941 (2016). Retrieved from
  4. Kornilova, et al, J. Biol. Chem., 278, 16470 (2003). Retrieved from


Product Spotlight from 10/25/16

The Bradykinin Bunch

As a part of the kinin system, Bradykinin has the ability to elevate vascular permeability and to cause vasodilation of arteries and veins in the aorta, gut, urethra, and uterus.  Not only is it a pro-inflammatory mediator, it is also a neuromediator and a vascular and renal function regulator1

According to research by Niewiarowska-Sendo et al, an abundance of kinins, including bradykinin, in nervous tissues can promote the degeneration of nerve tissue during neuroinflammation. This in turn can promote apoptosis in a Parkinson’s Disease model.  These findings may be helpful in designing new therapies against neurodegeneration2.


Bradykinin (Human, Bovine, Rat, Mouse) (0.5 mg vial)
(M.W. 1060.2)   C50H73N15O11    [58-82-2]

D-Arginyl-[Hyp3,Thi5,D-Tic7,Oic8]-Bradykinin (0.5 mg vial)
(M.W. 1304.5)   C59H89N19O13S    [130308-48-4]

D-Arginyl-[Hyp3,Thi5,8,D-Phe7]-Bradykinin (0.5 mg vial)
(M.W. 1294.5)   C56H83N19O13S2   [103412-42-6]


  1. Ch. Golias et al., Hippokratia.; 11(3), 124 (2007). (Review) Retrieved from
  2. A. Niewiarowska-Sendo, Mediators of Inflammation, 2016 (2016). Retrieved from

4002, 4293, 4293, and 4202.


Product Spotlight from 10/18/16


With the Society for Neuroscience Conference coming up in November, we are highlighting different neuropeptides that we offer at Peptides International. First up are the orexins.

Orexins, also called hypocretins, are neuropeptides that are synthesized by the neurons in the hypothalamus. The names are used interchangeably, where Hypocretin-1 and Hypocretin-2 are the same compounds as Orexin-A and Orexin-B, respectively. The compounds are derived from the 131 amino acid precursor protein. Orexin-A is a 33 amino acid peptide with a pyroglutamyl at the N-terminus and two intrachain disulfide bonds. Orexin-B, on the other hand, is a linear peptide with 28 amino acids. Orexins play a role in regulating food intake and energy expenditure as well as interact with Neuropeptide Y (NPY) and agouti-related peptide (AGRP). They also play a role in the release of hormones from the hypothalamus, regulating sleep, narcolepsy, and in cardiovascular and autonomic functions.1


Orexin-A (Human) (0.1 mg vial)
(M.W. 3561.1) C152H243N47O44S4   [205640-90-0]
(Disulfide bonds between Cys6-Cys12 and Cys7-Cys14) 

Orexin-A (Human) Antiserum (50 ul vial) 
Our undiluted antisera are suitable for immuno-histochemical use, for application to radioimmunoassay (RIA), or other non-isotopicimmunoassay systems These antisera are partially characterized by either of the following two methods: 1) (EIA) or 2) ELISA 
(Rabbit) Antiserum: lyophilized from 0.001 M Phosphate Buffer (pH 7.0) 
Immunogen: Orexin-A (Human)-BSA (BSA: Bovine Serum Albumin) 
Orexin-A (Human) + 
Orexin-B (Human) + 
Orexin-B (Rat) + 
GLP-1 (7-36 Amide) - 
Our undiluted antisera are suitable for immuno-histochemical use, for application to radioimmunoassay (RIA), or other non-isotopicimmunoassay systems. 
These antisera are partially characterized by either of the following two methods: 1) (EIA) or 2) ELISA. 
These products are not controlled to the rigorous specifications of prediluted antisera, which are adjusted to optimum concentrations for RIA and other immunoassays. 
These antisera are sold for research and development purposes only. 
Each antiserum has been lyophilized from 0.001 M Phosphate Buffer (pH 7.0). 
These Iyophilized antisera are stable for one month at room temperature. For long term storage, we recommend storing at -20 °C(freezer). After reconstitution with buffer, solutions may be kept at 4 °C for continuous use with a suitable preservative.

Orexin-A (Human, 17-33) (0.1 mg vial) 
OXA (17-33) Tyr-Glu-Leu-Leu-His-Gly-Ala-Gly-Asn-His-Ala-Ala-Gly-Ile-Leu-Thr-Leu-NH2
≧99.0% (HPLC)
(M.W. 1749.0) C79H125N23O22    [343268-91-7]
Orexin-1 Receptor Selective Agonist
N.A. German, A.M. Decker, B.P. Gilmour, B.F. Thomas, and Y. Zhang, ACS Med. Chem. Lett.4, 1224 (2013). (Original; Structure-Activity Relationship & Pharmacol.)

[Ala11, D-Leu15]-Orexin B (Human) (0.1 mg vial)
≧99.0% including Met(O) analog (≦1.0%) (HPLC)
(M.W. 2857.3) C120H206N44O35S    [532932-99-3]
Orexin-2 Receptor Selective Agonist

S. Asahi, S.-I. Egashira, M. Matsuda, H. Iwaasa, A. Kanatani, M. Ohkubo, M. Ihara, and H. Morishima, Bioorg. Med. Chem. Lett., 13, 111 (2003). (Original; Structure-Activity Relationship & Pharmacol.)
J. Putura, P.M. Turunen, M.H. Jäntti, M.E. Ekholm, and J.P. Kukkonen, Neurosci. Lett., 494, 57 (2011). (Pharmacol.) 

Orexin-B (Human) (0.1 mg vial)
(M.W. 2899.3) C123H212N44O35S     [205640-91-1]
Appetite-Boosting Peptide

T. Sakurai, A. Amemiya, M. Ishii, I. Matsuzaki, R.M. Chemelli, H. Tanaka, S.C. Williams, J.A. Richardson, G.P. Kozlowski, S. Wilson, J.R.S. Arch, R.E. Buckingham, A.C. Haynes, S.A. Carr, R.S. Annan, D.E. McNulty, W.-S. Liu, J.A. Terrett, N.A. Elshourbagy, D.J. Bergsma, and M. Yanagisawa, Cell, 92, 573 (1998). (Original)
L. de Lecea, T.S. Kilduff, C. Peyron, X.-B. Gao, P.E. Foye, P.E. Danielson, C. Fukuhara, E.L.F. Battenberg, V.T. Gautvik, F.S. Bartlett II, W.N. Frankel, A.N. van den Pol, F.E. Bloom, K.M. Gautvik, and J.G. Sutcliffe, Proc. Natl. Acad. Sci. U.S.A., 95, 322 (1998). (cDNA; Same Sequence [Hypocretin])
N. Takahashi, T. Okumura, H. Yamada, and Y. Kohgo, Biochem. Biophys. Res. Commun., 254, 623 (1999). (Pharmacol.)
T. Sakurai, Regul. Pept., 85, 25 (1999). (Review)
J.M. Siegel, Cell, 98, 409 (1999). (Review)
L. De Lecea and J.G. Sutcliffe, Cell. Mol. Life Sci., 56, 473 (1999). (Review)

Orexin-B (Rat, Mouse) (0.1 mg vial) 
(M.W. 2936.4) C126H215N45O34S    [202801-92-1]
Appetite-Boosting Peptide

T. Sakurai, A. Amemiya, M. Ishii, I. Matsuzaki, R.M. Chemelli, H. Tanaka, S.C. Williams, J.A. Richardson, G.P. Kozlowski, S. Wilson, J.R.S. Arch, R.E. Buckingham, A.C. Haynes, S.A. Carr, R.S. Annan, D.E. McNulty, W.-S. Liu, J.A. Terrett, N.A. Elshourbagy, D.J. Bergsma, and M. Yanagisawa, Cell, 92, 573 (1998). (Original)
L. de Lecea, T.S. Kilduff, C. Peyron, X.-B. Gao, P.E. Foye, P.E. Danielson, C. Fukuhara, E.L.F. Battenberg, V.T. Gautvik, F.S. Bartlett II, W.N. Frankel, A.N. van den Pol, F.E. Bloom, K.M. Gautvik, and J.G. Sutcliffe, Proc. Natl. Acad. Sci. U.S.A., 95, 322 (1998). (cDNA; Same Sequence [Hypocretin])
N. Takahashi, T. Okumura, H. Yamada, and Y. Kohgo, Biochem. Biophys. Res. Commun., 254, 623 (1999). (Pharmacol.)
M.S. Mondal, M. Nakazato, Y. Date, N. Murakami, M. Yanagisawa, and S. Matsukura, Biochem. Biophys. Res. Commun., 256, 495 (1999). (Distribution)
J.M. Siegel, Cell, 98, 409 (1999). (Review)
L. De Lecea and J.G. Sutcliffe, Cell. Mol. Life Sci., 56, 473 (1999). (Review)


  1. L. Martynska, et al., Neuroendocrinology Letters, 26 (4), 289, (2005). Retrieved from


Product Spotlight from 10/11/16

Angiogenic Peptides

Angiogenesis is the process by which new capillary blood vessels are generated. Thrombospondin-1 (TSP-1) interacts directly with vascular endothelial growth factor (VEGF) and indirectly with several endothelial cell TSP-1 receptors to inhibit an angiogenic response.1 It can also inhibit angiogenesis by disrupting vascular endothelial growth factor receptor-2 (VEGFR-2) phosphorylation and signaling.2

CD47 is a protein found on the surface of cells that signals macrophages whether or not to remove aging or damaged cells. In cancer treatment, it can be useful to inhibit new blood vessel growth to cancerous cells, causing a loss of blood supply to these cells resulting in apoptosis.3

In addition to cancer research, angiogenic peptides can be useful in the study of wound healing. Both TSP-1 and CD47 also regulate wound healing. Our product, TSP-3873-PI, is a TSP1-derived CD47-binding peptide 7N3, with the sequence of FIRVVMYEGKK. Isenberg, et al., reported TSP-3873-PI significantly inhibits the binding of TSP-1 to CD47.4 We also offer the control peptide, TSP-3874-PI, with the sequence of FIRGGMYEGKK.

Here are the two new angiogenic peptides that Peptides International offers:




  1. S. Kaur, et al., J. Biol. Chem., 285, 38923 (2010). Retrieved from
  2. S. Kaur, et al., J. Immunol., 193 (8), 3914–3924 (2014).   Retrieved from
  3. CD47. Stanford University Institute for Stem Cell Biology and Regenerative Medicine. Retrieved from   
  4. J.S. Isenberg, et al., J. Biol. Chem., 284 (2), 1116 (2009). Retrieved from