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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 1.72×105 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 Co2+, and inhibited by EDTA. The N-terminal amino acid sequence of the enzyme was determined as ATFDYNKYHSYQEIMDWVTN. [Copyright &y& Elsevier]

Abstract: Phospholipase A (PLA) activities in the pyloric ceca and viscera from seven species of marine invertebrates (four starfish, one sea urchin, and two shellfish) were determined. Relatively high PLA specific activities were found in the pyloric ceca of two species of starfish (Coscinasterias acutispina and Plazaster borealis). Phospholipase A2s (PLA2s) were partially purified from the pyloric ceca of the starfish, C. acutispina PLA2 (C-PLA2) and P. borealis PLA2 (P-PLA2). The C-PLA2 and P-PLA2 mainly released oleic acid from 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine. Temperature optima of the C-PLA2 and P-PLA2 were at around 60 °C and 50 °C, respectively, and pH optima of the C-PLA2 and P-PLA2 were both at around pH 10.0. The activities of the C-PLA2 and P-PLA2 were enhanced by sodium deoxycholate and 1 mM or higher concentration of Ca2+. The C-PLA2 and P-PLA2 did not show the fatty acid specificity for hydrolysis of phosphatidylcholine. Unlike porcine pancreatic PLA2, the C-PLA2 and P-PLA2 hydrolyzed phosphatidylcholine more effectively than phosphatidylethanolamine. [Copyright &y& Elsevier]