The site of action of phosphatide acyl-hydrolase (phospholipase A) on mixed-acid phosphatides containing a poly-unsaturated fatty acid

In order to establish the positional specificity of phospholipase A, two structural isomeric -α-phosphatidyl ethanolamines were prepared by a synthesis de novo. The phospholipase present in Crotalus adamantheus venom liberated nearly one equivalent palmitic acid from (γ-linolenoyl-β-palmitoyl-)-α-phosphatidyl ethanolamine, while practically one equivalent of linolenic acid was released from (γ-palmitoyl-β-linolenoyl-)-α-phosphatidyl ethanolamine. Hence, the studied phospholipase acts specifically on fatty acids esterified in β-position of the phospholipid molecule and does not show any preferential hydrolysis of poly-unsaturated fatty acid constituents