Product Spotlight for 7/14/2020: "SARS-CoV / SARS-CoV-2 Main Protease Fluorescent Substrates"

New England Peptide | Peptides International is pleased to announce three types of substrates for the SARS-CoV main protease (SARS-CoV Mpro or 3CLpro) and SARS-CoV-2 main protease (SARS-CoV-2 Mpro). Protease activity can be measured by observing the increase in fluorescence by the main protease cleaving the substrate, useful in the research of inhibitors.

By Yukie Nohara (Peptide Institute)

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is the causative virus of a new coronavirus infection (COVID-19), which has been spreading worldwide since the end of 2019. When a virus infects a host cell, the RNA from the virus translates a large precursor protein. The precursor protein is cleaved by various proteases, and becomes a functional protein required for virus growth such as RNA-dependent RNA polymerase. SARS-CoV-2 Mpro, which is also one of the cleavage products, plays a major role in cleavage of precursor proteins and is an essential protease for viral growth. Therefore, this “main protease” inhibitor may be an antiviral drug and is being developed all over the world.

Quenching fluorescent substrate using FRET of SARS-CoV / SARS-CoV-2 Mpro 1,2,3

The precursor protein sequence, Thr-Ser-Ala-Val-Leu-Gln ↓ Ser-Gly-Phe-Arg-Lys-Met [↓ is a cleavage site] and a fluorescent group (Edans) and a quenching group (Dabcyl) are introduced. SARS-CoV Mpro cleaves the Gln-Ser sequence between the fluorescent and quencher groups, resulting in increased fluorescence. By observing this fluorescence, the protease activity can be measured [KM=17μM, kcat=1.9s-1 (kinetic parameter for SARS-CoV Mpro)]1 [KM =33μM (SARS-CoV-2 Kinetic parameters for Mpro)].3

Figure 1. Method of measuring protease activity of SARS-CoV/SARS-CoV-2 Mpro quenching fluorescent substrate using FRET

SFS-3249-v Dabcyl-Lys-Thr-Ser-Ala-Val-Leu-Gln-Ser-Gly-Phe-Arg-Lys-Met-Glu(Edans)-NH2                      

Ac-Abu-Tle-Leu-Gln-MCA and Ac-Thz-Tle-Leu-Gln-MCA

4-methylcoumarin-7-amide (MCA) type fluorescent substrate in which aminomethylcoumarin (AMC) is introduced into two sequences with high affinity for SARS-CoV-2 Mpro, as reported by Drag et al. When the non-fluorescent MCA-bound substrate is cleaved by SARS-CoV-2 Mpro, AMC with strong fluorescence is released. By observing this fluorescence, protease activity can be measured. (Ex: 380nm / Em: 460nm)

SFP-3250-v Ac-Abu-Tle-Leu-Gln-MCA  

SFP-3251-v Ac-Thz-Tle-Leu-Gln-MCA                                       

Other CoV related products:

MRR-3155-v Boc-Arg-Val-Arg-Arg-MCA (Substrate for Furin)     

MPR-3159-v Pyr-Arg-Thr-Lys-Arg-MCA (Substrate for Furin)   

MCA-3206-v Ubiquitin-MCA (Substrate for PLPro)    

MCA-3099-v AMC (Reference Compound)    

ILP-4041 Leupeptin (Inhibitor for TMPRSS2)

IED-4321-v E-64-d (Inhibitor for Thiol Protease)