CLEAR™ Resins (Technical Tips)
CLEAR (Cross-Linked Ethoxylate Acry- late Resins) was developed by George Barany and Maria Kempe at the University of Minnesota. These products retain the highly desirable solvation properties of polyethylene glycol (PEG) or of PEG-linked products but with greater convenience.1,2,3 Unlike conventional liquid phase synthesis, developed by Bayer and Mutter in the 1970’s4 and recently popularized by Janda in combinatorial synthesis,5 CLEAR resin is a highly cross-linked solid support. It is produced in a bead form using a large-scale polymerization process developed at Peptides International.6 The Ala10 Prepared on CLEAR ↓ Analytical HPLC chromatogram of crude H-(Ala)10-Val-NH2 prepared by batch-wise automated synthesis (Rainin, PS-3) on CLEAR-Amide resin. Synthesis performed using HBTU as coupling agent, four fold excess of Fmoc-Ala for 30 + 90 minutes (double coupling). HPLC performed on Vydac C18 column (4.6 x 250 mm), gradient 5% →65% ACN/0.05% TFA in 60 minutes, 1 ml/min, 220 nm. CLEAR particles swell in a wide range of solvents including water, dichloromethane (DCM), or dimethylformamide (DMF). They are also compatible with relatively non-polar solvents such as tetrahydrofuran (THF) or dioxane. Synthesis can be performed on CLEAR in automated or manual synthesizers. Applications for multiple parallel synthesis and combinatorial chemistries are under development. Clearly, your own imagination should lead to many other uses for a product as exciting as CLEAR. Organic Synthesis? Affinity Chromatography? Enzyme Immobilization? Trace Analysis? Remote Sensor Applications? Isn’t it CLEAR what your next solid-phase support choice should be?
1. M. Kempe and G. Barany, “CLEAR: A Novel Family of Highly Cross-Linked Polymeric Supports for Solid Phase Synthesis”, J. Am. Chem. Soc., 118, 7083-7093, (1996).
2. M. Kempe and G. Barany, “Novel Highly Cross-Linked Polymeric Supports for Solid Phase Applications”, in Solid Phase Synthesis (Fourth International Symposium, Edinburg Scotland) R. Epton, Ed., Mayflower (London) 1996, pp. 191-194.
3. CLEAR products are protected under US Patents 5,910,554 and 5,656,707 granted to the Regents of the University of Minnesota.
4. E. Bayer and M. Mutter, Nature (London), 237, 512 (1972).
5. K.D. Janda, “Tagged versus Untagged Libraries: Methods for Degeneration and Screening of Combinatorial Libraries, Proc. Natl. Acad. Sci. USA, 91, 10779-10785 (1994).
6. K. Darlak, I. Romanovska, A.F. Spatola, G. Barany, and M. Kempe, “A New Solid Support for Peptide and Organic Synthesis”, Fifteenth American Peptide Symposium; Nashville, Tennessee, USA; June 1997.