Studies on Digestive Enzyme Activities of Portunus trituberculatus

The effects of temperature and pH on the activities of protease,amylase and cellulase of Portunus trituberculatus midgut gland and the digestive enzymes(protease,trypsin,chymotry psin,carboxypeptidase A,carboxypeptidase B,amylase,cellulase and liapse) from different digestive tissues of Portunus trituberculatus were studied by using enzyme analytical method.The results indicated that: the optimal temperatures were 55℃ for protease and amylase and 65℃ for cellulase,the optimal pH values were 7～8 for protease, 7.5 for amylase,and 4.8 for cellulase.The protease,amylase,and cellulase from Portunus trituberculatus midgut gland had high thermostability and pH-stability in 2h and 4 h.The protease,trypsin,carboxypeptidase A and carboxypeptidase B had higher activity in the midgut gland than the stomach and intestine,and the chymotrypsin activity had not been found in the stomach and intestine.Amylase had the same activity in the midgut gland,the stomach and intestine,lipase and cellulase had higher activity in the stomach and intestine than the midgut gland.