Metabolism of plasmalogen. 3. Relative reactivities of acyl and alkenyl derivatives of glycerol-3-phosphorylcholine.

(I) The alkenyl ether derivatives of phospholipids (plasmalogens) react at slower rates than the acyl analogs in several enzyme-catalyzed reactions. (2) Alkenylglycerol-3-phosphorylcholine is essentially inert as a substrate for acyl-CoA : phospholipid acyltransferase. This result suggests that in viuo the a-acyl substituent may be present before the alkenyl ether group is formed in the molecule. (3) Alkenyl acylglycerol 3-phosphorylcholine is essentially inert as a substrate for cabbage phospholipase D (EC 3.1.4.4.). This lack of reactivity allows a convenient separation of alkenyl acylglycerol 3-phosphorylcholine from its diacyl analog in naturally occurring mixtures.