Properties of two chymotrypsins from the digestive gland of prawn Penaeus monodon

Abstract

For the first time chymotrypsins have been isolated from the hepatopancreas of prawn. Two purified chymotrypsins from Penaeus monodon were found to be single-chained with molecular masses of 27 and 26 kDa, respectively. They have chymotrypsin-like specificities, and cleave the insulin chain B preferentially on the carboxyl side of tyrosyl, phenylalanyl and leucyi residues. They were effectively inhibited by soybean trypsin inhibitor, turkey and chicken ovomucoid, chymostatin, PMSF, Z-AlaGlyPhe chloromethyl ketone but not by Z-Phe chloromethyl ketone and many other small protease inhibitors. The shrimp enzymes hydrolyze protein substrates as rapidly as but small substrates much slower than bovine chymotrypsin, suggesting the importance of an extended substrate interacting site.