Stimulation of Phosphorylcholine–Glyceride Transferase Activity by Unsaturated Fatty Acids

Abstract

A number of unsaturated fatty acids markedly stimulate chicken liver microsomal phosphorylcholine–glyceride transferase (CDP-choline:1,2-diglyceride cholinephosphotransferase, EC 2.7.8.2). Oleate (0.8 mM) activates this enzyme severalfold only if a mixed diglyceride such as 1-palmitoyl-2-oleoyl-sn-glycerol is used as a substrate for the reaction. Dipalmitin and diolein incorporation into lecithin is not stimulated to any significant extent by unsaturated fatty acids. Fatty acid esters and numerous detergents either inhibit the enzyme or have no effect. Phosphorylethanolamine–glyceride transferase (CDP-ethanolamine:1,2-diglyceride ethanolaminephosphotransferase, EC 2.7.8.1) activity is only very slightly stimulated while diglyceride O-acyltransferase activity is inhibited to a small extent.