Chromogenic substrates for papain with a C-terminal S-benzylcysteine residue

Abstract

Two types of chromogenic substrates for papain were prepared, namely p-nitroanilides of N-acetyltripeptides of general formula Ac-Leu-Leu-A-NAn, where A = Gly, Ala, Leu, and p-nitroanilides of 3-carboxypropionyldi- and tripeptides of general formula Suc-B-Cys(Bzl)-NAn, where B = Gly, Gly-Gly, Ala, Ala-Ala, Leu, Leu-Leu, Gly-Leu, Leu-Ala and Ala-Met. The values of Km, kcat and C (kcat/Km) for these substrates were determined. Suc-Leu-Leu-Cys(Bzl)-NAn is the best substrate for papain its C being 60 000 mol-1 l s-1.