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 (Anb5,2). 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 Anb5,2 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.
acid preloaded to Wang Resin
AnaSpec presented a poster at the recent ABRF meeting in San Antonio, Texas,
Solid-Phase Synthesis of Peptide-7-p-Nitroanilide (pNA) Analog
Containing Conjugates Using a Novel Wang or Rink Amide Resin.”
Hojo, K. et al. Chem. Pharm. Bull. U.S.A. 48,