Characterization of phospholipase A2 from the pyloric ceca of two species of starfish, Coscinasterias acutispina and Plazaster borealis

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.