Polyunsaturated fatty acids in beef heart mitochondria and derived enzymically active lipoprotein fractions.

The dietary deficiency of essential fatty acids results in anatomical changes in animals, which are accompanied by changes in the polyunsaturated fatty acid content of the tissues (1). The chemical manifestations of the deficiency are principally a greatly increased content of trienoic acids and a decrease in the other polyunsaturated acids in the tissues, notably in the heart and liver (2). Klein and Johnson (3) have demonstrated that polyunsaturated acids occur in the subcellular granules, and that changes in the polyunsaturated acids content of these granules begin much earlier in the deficiency than the external symptoms appear (4). Essential fatty acid deficiency is accompanied by an abnormal metabolism. Burr and Beber (5) found that deficient rats have a higher basal metabolic rate, higher specific dynamic action of foods, and higher respiratory quotients than do normal rats. Deficiency has been found to cause changes in the enzyme activities of tissues. Endogenous respiration of the liver decreases, liver cytochrome oxidase increases, choline oxidase increases slightly, the titer of antimycin A-sensitive factor increases, and the P:O ratios of enzyme preparations decrease markedly in deficiency (6, 7). In fat deficiency, succinic dehydrogenase, glutamic dehydrogenase, and butyric dehydrogenase activities are also reduced significantly (8). Ultraviolet irradiation of rat liver mitochondria, or the addition of partly oxidized linoleate or linolenate, factors which could induce oxidation of polyunsaturated fatty acids, were found to inhibit succinoxidase activity (9). These several lines of evidence suggest that polyunsaturated acids are necessary for or are involved in some enzyme activities. In the light of the information summarized above, it seemed pertinent to measure the content of polyunsaturated acids in enzyme preparations of mitochondrial origin. The data presented here show that polyunsaturated acids are present in significant amounts in these enzyme complexes, and are consistent with the suggestion that polyenoic acids may have some function in the enzymatic reactions catalyzed by these complexes.