PURIFICATION AND PROPERTIES OF PHOSPHOLIPASE A2 ISOZYMES FROM PYLORIC CECA OF THE STARFISH (ASTERINA PECTINIFERA)

Phospholipase A₂ isozyme II (PLA₂ II), which showed different mobility on native PAGE from that of the PLA₂ isozyme I (PLA₂ 1) isolated previously, was purified from pyloric ceca of the starfish (Asterina pectinifera). The PLA₂ II mainly released oleic acid from 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine. N-terminal amino acid sequence of the PLA₂ II was SVYQF. Temperature and pH optima of the PLA₂ II were at around 50C and pH 9.0, respectively, and the enzyme activity was enhanced by sodium deoxycholate and 1 mM or higher concentration of Ca²⁺. The PLA₂ II did not show fatty acid specificity for hydrolysis of phosphatidylcholine (PC). Specific activity of the PLA² II was about 10 times higher than that of commercially available porcine pancreatic PLA₂. The PLA₂ II hydrolyzed PC more effectively than phosphatidylethanolamine. These characteristics of the PLA₂ II were the same as those of the PLA₂ I.