Reduced Triphosphopyridine Nucleotide Oxidase-catalyzed Alterations of Membrane Phospholipids

Abstract

Abstract Oxidation of TPNH by liver microsomes from normal rats resulted in a concomitant disappearance of polyunsaturated fatty acids (primarily arachidonic acid) from the membrane phospholipids. The utilization of the polyunsaturated fatty acids was completely dependent on the presence of TPNH in the system. As much as 15% of the total microsomal fatty acids was consumed by the reaction within 30 to 45 min. Since the ester value of the phospholipids remained constant, it was evident that polyunsaturated fatty acids were being converted to some as yet unidentified moiety in situ on the phospholipid. The reaction showed greatest specificity for arachidonic acid at the β-acyl position. The polyunsaturated fatty acids in both phosphatidylethanolamine and phosphatidylcholine were consumed. The altered phospholipids were shown to be considerably more polar than normal microsomal phospholipids. They were still subject to the action of phospholipase A, however.