Purification and Characterization of Proteases from Digestive Tract of Grass Shrimp ( <i>Penaeus monodon</i> )

Abstract

ABSTRACT Proteases in grass shrimp ( Penaeus monodon ) digestive tract were extracted. Four fractions, A, B, C and D, demonstrated caseinolytic activity and were purified to electrophoretic homogeneity. A, C and D were trypsin‐like, while B was a chymotrypsin‐like protease. Optimal temperature for proteases A, B and C were 65°C, and that for D was 55°C for hydrolysis of casein. Optimal pH of proteases A and C was 8.0, and that of D was 7.0 for hydrolysis of p‐toluenesulfonyl‐L‐arginine methyl ester. Optimal pH of protease B for hydrolysis of N‐benzoyl‐L‐tyrosine ethyl ester was 8.0. Inactivation of 50 % enzyme activity in 5 min occurred at 67°C for protease B and 50°C for proteases A, C and D.