Partial purification and product characterization of fatty acid ethyl ester synthases in rabbit myocardium

Homogenates of rabbit ventricular myocardium synthesize fatty acid ethyl esters using as substrates nonesterified fatty acid and ethanol in the absence of coenzyme A and ATP. This catalytic activity resides in two soluble cytosolic enzymes accounting for 19 and 81% of total fatty acid ethyl ester synthetic capability. These enzymes have been separated and partially purified by anion exchange chromatography. Gas chromatographic/mass spectrometric analyses of the catalytic products formed by these enzymes from nonesterified fatty acid and ethanol confirm their identity as ethyl esters of fatty acids. Kinetic studies indicate apparent Km values for ethanol of 0.65 M and 0.75 M for the minor and major activities, respectively. These data confirm the presence of a myocardial pathway for nonoxidative ethanol metabolism and for a metabolism of fatty acids independent of coenzyme A.