Phospholipase A2 Activity

Phospholipases A₂ (PLA₂ s) are important enzymes in signal transduction, being responsible for release of arachidonate from membrane phospholipids for the production of prostaglandins, leukotrienes, platelet-activating factors, and other bioactive lipids (1 ). Phospholipids are composed of a glycerophosphate in which the two hydroxyls are esterified with long-chain fatty acids and the phosphoryl moiety forms a phosphodiester bond with a polar “head group,” commonly choline, ethanolamine, serine, and inositol. Phospholipid structures are designated by a stereospecific nomenclature (sn ) based on L-glycerol-3-phosphate. Thus, the fatty acid esterified to carbon-l of the glycerol backbone is termed the “sn-l ” fatty acid, and is commonly saturated, e.g., palmitate. The fatty acid esterified to carbon-2 of the glycerol backbone is the sn 2 fatty acid, and is often polyunsaturated, e.g., arachidonate.