Journal of Lipid Research (Sep 1972)
Enzymic synthesis of 1-alkyl-2-acyl-sn-glycero-3-phosphorylethanolamines by the CDP-ethanolamine:1-radyl-2-acyl-sn-glycerol ethanolaminephosphotransferase from microsomal fraction of rat brain
Abstract
The incorporation of radioactivity from cytidine-5′-phosphate-[32P]phosphorylethanolamine into 1-alkyl-2-acyl-sn-glycero-3-phosphorylethanolamines and 1,2-diacyl-sn-glycero-3-phosphorylethanolamines was stimulated more than fourfold by 1-alkyl-2-acyl-sn-glycerols and 1,2-diacyl-sn-glycerols, respectively, with an ethanolaminephosphotransferase (EC 2.7.8.1) present in the microsomal fraction from brains of mature rats. The Km, values, 0.28 mm for CDP-ethanolamine and 1.9 mm for 1-alkyl-2-acyl-sn-glycerols, were similar to those obtained by other investigators with other 1-radyl-2-acyl-sn-glycerols. The formation of 1,2-diacyl-sn-glycero-3-phosphorylethanolamines from endogenous 1,2-diacyl-sn-glycerols was inhibited by 1-alkyl-2-acyl-sn-glycerols.These properties indicate that the ethanolaminephosphotransferase lacks specificity for the type of group at the 1-position of the lipid substrate. The synthesis of 1-alkyl-2-acyl-sn-glycero-3-phosphorylethanolamines from 1-alkcyl-2-acyl-sn-glycerols and CDP-ethanolamine by an enzyme from rat brain supports the inclusion of this reaction in the metabolic pathway for the synthesis of 1-alk-1′-enyl-2-acyl-sn-glycero-3-phosphorylethanolamines.
