Biosynthesis of monoacyl‐sn‐glycerol 3‐phosphate by rabbit heart mitochondria: Positional specificity differing from liver enzyme

Rabbit heart mitochondria synthesize comparably more monoacyl‐than diacylglycerol 3‐phosphate as compared to heart microsomes. Since the fatty acid specificity of the biosynthesis by cardiac enzymes differs from that by hepatic enzymes, the positional specificity of monoacylglycerol 3‐phosphate formation by mitochondria was investigated by using a method utilizing lysosomal phosphatidate phosphohydrolase and borate‐impregnated thin layer chromatography. Contrary to the results of studies with liver particulates, ca. one‐third of palmitate was found at position 2 of the glycerol moiety and the remainder at position 1, whereas one‐third of oleate was bound at position 1. Only a slight, asymmetric distribution was observed with linoleate as the acyl donor. Thus, our study indicates that preferential acylation of individual fatty acids during the formation of monoacylglycerol 3‐phosphate is not as distinct in the heart mitochondria as in the liver mitochondria and microsomes.