Characteristic of digestive proteolysis of the crabs portunus trituberculatus portunus sanguinolentus and charybdis japonica
Galgani, F.; Nagayama, F.
Nippon Suisan Gakkaishi 52(12): 2183-2188
The characteristics of digestive proteolysis and digestive proteinases in the crabs Portunus trituberculatus, Portunus sanguinolentus and Charybdis japonica were studied. For these three species, a broad range of stable protease activity from pH 6-8 was found. Optimum temperature was found to be around 60.degree. C. Proteolytic activity is stable between pH 6-8 and effects of metallic ions are similar in the three species. Trypsin, carboxypeptidase A and leucine aminopeptidase were identified in the digestive glands of three species using synthetic substrates. However, neither chymotrypsin nor carboxypeptidase B were found. Hydrolysis of native collagen occurs in the digestive glands of three species. In addition, after gel filtration, a proteolytic activity was observed in a low molecular weight fraction. Optimum pH for trypsin was found around 8-8.5.