The Role of Acyldihydroxyacetone Phosphate, Reduced Nicotinamide Adenine Dinucleotide, and Reduced Nicotinamide Adenine Dinucleotide Phosphate in the Biosynthesis of O-Alkyl Glycerolipids by Microsomal Enzymes of Ehrlich Ascites Tumor

Abstract

Abstract Palmitoyl dihydroxyacetone phosphate and [1-14C]hexadecanol were found to serve as precursors of O-alkyl lipids in a microsomal system from Ehrlich ascites tumor. Both acyldihydroxyacetone phosphate and dihydroxyacetone phosphate were tested. The system required no CoA when acyldihydroxyacetone phosphate was used as the glycerol source, and significantly lower concentrations of acyldihydroxyacetone phosphate than dihydroxyacetone phosphate were required for the optimal biosynthesis of O-alkyl lipids; a similar reaction was catalyzed by microsomal preparations from mouse preputial gland tumors. These findings indicated that acyldihydroxyacetone phosphate is a more efficient precursor of O-alkyl lipids than dihydroxyacetone phosphate. The CoA, ATP, and Mg++ that are required when dihydroxyacetone phosphate is the glycerol source are necessary for the formation of the acyldihydroxyacetone phosphate; the synthesis of acyldihydroxyacetone phosphate from [14C]dihydroxyacetone phosphate and palmitic acid was demonstrated in the microsomal system. The O-alkyldihydroxyacetone phosphate formed in the system was reduced by either NADPH or NADH to 1-O-alkylglycerophosphate and subsequently acylated to form 1-O-alkyl-2-acylglycerophosphate. The data also indicated that acyldihydroxyacetone phosphate was reduced to acylglycerophosphate by both NADH and NADPH. The organic synthesis of acyldihydroxyacetone phosphate is outlined as well as the identification of biosynthetic products.