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.