Substrate-specific forms of human platelet phospholipase A2.

摘要: Purification of human platelet phospholipase A2 (PLA2) from a particulate fraction by ion-exchange chromatography at 4 degrees C yielded single peak enzyme activity, which catalyzed the hydrolysis arachidonic acid 2-position phosphatidylcholine (PtdCho) and phosphatidylethanolamine (PtdEtn). The activity toward PtdCho that PtdEtn differed in stability during storage, pH optimum, Ca2+ requirement, affinity for substrate; however, each preferred phospholipid with arachidonate 2-position. two activities appeared to be eluted as an aggregate column. When column was run 22 C, additional PLA2 specific resolved original peak. But when briefly sonicated 0.1% octylglucoside before different peak, PtdCho, obtained. Resolution forms under conditions probably resulted selective solubilization aggregate. thus isolated were very labile, whereas those relatively stable. These findings suggest platelets contain least substrate-specific PLA2, one another PtdEtn.