| A detailed literature review of studies on Digestive Enzymes in Crustacean around the world was undertaken. In this paper, Characterization of the digestive enzymes from Portunus trituberculatus were studied by using enzyme analytical method . Research about (1) Relation between digestive enzyme activity and temperature and pH in Portunus trituberculatus midgut gland. Thermostability and pH-stability of the digestive enzyme activities from Portunus trituberculatus midgut gland. (2)The effect of substrate and concentration from Portunus trituberculatus on digestive enzyme activity. (3)The effect NaCl on the activity of digestive enzyme from Portunus trituberculatus by adjusting the assay mixture. (4)Effects of metal ions on digestive enzyme activities of Portunus trituberculatus. The result are summarized as follow:1 Optimal temperature for protease and amylase were 55℃, and for cellulase 65℃; Optimal pH of protease was 7-8, of amylase was 7.5, of cellulase was 4.8. The digestive enzymes from Portunus trituberculatus midgut gland had high thermostability and pH-stability in short time. In different digestive tissues, the highest protease activity was found in the midgut gland. Amylase activities were not significantly different in different digestive tissue of Portunus trituberculatus. In the Stomach and intestine, lipase and cellulase have higher activity than the midgut gland.2, Protease, trypsin, chymotrypsin, carboxypeptidase Ax carboxypeptidase B, amylase, cellulase got to their peaks for substrate concentrations of 5mg/ml, 0.6mM, 1 mM, 0.5 mM, 0.45 mM, 4mg/ml , 0.6mg/ml on casein, TAME, SAPPN, HPA, HA, starch, Carboxymethyl cellulose respectively. The Km of protease, trypsin, chymotrypsin, carboxypeptidase A, carboxypeptidase B, amylase, Cellulase were 1. 185mg/ml, 0. 132mM, 0. 147mM, 0. 119mM, 0. 194mM,1.25 mg/ml, 0. 3mg/ml toward caseiiu TAME, SAPPN, HPAs HA, starch,Carboxymethyl cellulose. BAEE was the most suitable substrate of trypsin from Portunus trituberculatusmidgut gland. Activities of trypsin have organic specificity and substrate difference.3s The effects of ten metal ions(Cu2+, Mg2+,Fe3+,Hg2+ Zn2+, Ca2+, Cd2+,Pb2+, Ag+ and Mn2+)on the activities of proteases Trypsins Chymotrypsin, Carboxypeptidase As Carboxypeptidase Bs Amylases and cellulase of Portunus trituberculatus were studied by using enzyme analytical method at the different concentration levels (5X 10-4mol/L, 1X10-3 mol/L, 5X 10-3mol/L). The experimental results indicated , in the scope of the concentrations of this experimental, Ca2+ , Mn2+, Mg2+, Fe3+, Pb2+in 0. 5mM had no significant effects on protease, the others metal ions had significant effects. In the scope of the concentrations of this experimental, Ca2+, Cd2+, Mg2+, Mn2+had significant activation on trypsin. Chymotrypsin was activated by Ca^ in the scope of this experimental and by Mg2+ and Cu2+ at low concentration. Carboxypeptidase A activity was enhanced by Hg2+in the scope of this experimental and by Mg2+, Mn2+, Zn2+ at low concentration. Carboxypeptidase B activity was enhanced by Ca2+ in the scope of this experimental and by Mg2+ at low concentration. Amylase activity was enhanced by Ca2+, Cd2+, Mn2+in the scope of this experimental and by Zn2+, Fe3+,Pb2+ at low concentration.4 The effects of NaCl on the activities of proteases trypsins chymotrypsins Carboxypeptidase As Carboxypeptidase B and amylase of Portunus trituberculatus were studied by adjusting the assay mixture (Os 0.005s O.OO1, 0.05, O.1, 0.5, 1. 0 and 2.0 M) . The experimental results indicated, -except Carboxypeptidase B, all enzyme were activated by NaCl at low concentration. Protease activity .was better activated at NaCl concentration around 0.1-0.5M. Trypsin activity was better activated atNaCl concentration around 0.5M. Chymotrypsin activity has more high activity at NaCl concentration around ImM. Carboxypeptidase A was better activated at NaCl concentration around 0.05-0.1M. Carboxypeptidase B was inhibited by NaCl concentration, but 60% maximum activities at 2M NaCl. A...
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