Enzymatic Properties of a Protease From the Hepatopancreas of Shrimp, Penaevs Omentaim

The protease purified from hepatopancreas of shrimp, Penaeus orientals, had high proteolytic activity in the pH range of 7.0 to 9.5. Temperature optimum for hydrolysis of casein was 70C. The protease was stable at neutral and alkaline pH and unstable at acidic pH. The apparent Michaelis-Menten constant (Km) and the turnover number (Vmax) of the protease on hydrolysis of N-CBZ-L-tyrosine p-nitrophenyl ester (CBZ-Tyr-NE) and N-CBZ-L-phenylalanine p-nitrophenyl ester (CBZ-Phe-NE) -were similar, however, those for N-CBZ-L-cysteine p-nitropher.yl ester (CBZ-Cys-NE) were different. Km and Vmax for hydrolysis of casein by the protease were determined to be 0.31% and 5.21s-1, respectively. The N-terminal sequence of the protease showed higher homology with the collagenase of crab and trypsins from Crustacea. Myosin heavy chain (MHC) was the primary substrate during proteolysis with the protease. Actin/tropomyosin were degraded progressively during 2 h incubation but to a lesser extent than MHC.