Colorimetric based Peptide-p-Nitroanilide conjugates (peptide-pNAs), with absorbance at approximately 408 nm, have historically been and are still widely used substrates for the study of protease activity. However, the preparation of peptide-pNA presents technical challenges. The amino group of pNA has a low nucleophilic property due to the electron-withdrawing effect of the nitro group; poor solubility of a p-nitroanilide intermediate and coupling in solution phase by DCC, azide or active ester, techniques commonly used are not effective.

Chemists at AnaSpec, Eurogentec Group have developed a Wang resin conjugated with a pNA analog, 5-amino-2-nitrozenzoic acid (Anb^5,2). This novel support for facile solid phase pNA-like peptide substrate syntheses was developed based in part on a paper by Hojo, et al. in which they described the introduction of Anb^5,2 to a p-methylbenzhydrylamine (MB) resin. The Wang preloaded resin is a useful tool for the synthesis of peptide with a C-terminal pNA- analog, Anb.


Figure 1. Structure of Anb-Wang Resin.

AnaSpec presented a poster at the recent ABRF meeting in San Antonio, Texas, entitled, “Facile Solid-Phase Synthesis of Peptide-7-p-Nitroanilide (pNA) Analog Containing Conjugates Using a Novel Wang or Rink Amide Resin.”

Reference

Hojo, K. et al. Chem. Pharm. Bull. U.S.A. 48, 1740 (2000).