Characteristics of carboxypeptidase B from pyloric ceca of the starfish:Asterina pectinifera

Abstract Carboxypeptidase B was purified from the pyloric ceca of the starfish, Asterina pectinifera . The final enzyme preparation was nearly homogeneous in sodium dodecyl sulfate–polyacrylamide gel electrophoresis and its molecular weight was estimated as approximately 34,000. The value of the specificity constant ( k cat / K m ) for hydrolysis of benzoyl-glycyl- l -arginine by the purified enzyme was 1.72 × 10 5  M −1  s −1 . The optimal pH and the optimal temperature of the enzyme were pH 7.5 and 55 °C, respectively. The enzyme was unstable above 50 °C and below pH 5.0. The enzyme was activated by Co 2+ , and inhibited by EDTA. The N-terminal amino acid sequence of the enzyme was determined as ATFDYNKYHSYQEIMDWVTN.