Purification and characterization of proteases from oyster (Crassotrea gigas)
1991
Tsao, C.Y. | Nagayama, F.
Proteases in oyster (Crassotrea gigas) were extracted with 10 mM Tris-HCl buffer solution and purified by ammonium sulfate fractionation, Sephadex G-150 gel filtration, repeated DEAE-Sephadex A-50 and CM-Sepharose CL-6B chromatography. Three fractions with caseinolytic activity, named I, II and III, were obtained from CM-Sepharose CL-6B and DEAE-Sephadex A-50 chromatography. The three proteases were purified to electrophoretic homogeneity. Substrate specificity studies indicated that protease I was a carboxypeptidase A-like enzyme; II and III were trypsin-like enzymes. The optimal pH of protease I for hydrolysis of hippuryl-L-phenylalanine was 9.0, II and III for hydrolisis of p-toluenesulfonyl-L-arginine methyl ester (TAME) was 8.0. The temperatures which inactivated 50% of enzymes were 78 degrees C for protease I in 30 min; 50 and 52 degrees C for protease II and III, respectively, in 5 min. The molecular weights of proteases I, II and III were 23,000, 34,400 and 31,000, respectively.
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