Degradation of Unsaturated Fatty Acids. Identification of Intermediates in the Degradation of cis-4-Decenoyl-CoA by Extracts of Beef-Liver Mitochondria

Abstract

Cis-4-Decenoyl-CoA, an intermediate of linoleic acid catabolism, is degraded by a soluble enzyme fraction of beef liver mitochondria to octanoyl-CoA. cis-2-Octanoyl-CoA is not observed among the intermediates of this degradation sequence. The existence of a mitochondrial 4-enoyl-CoA reductase [EC 1.3.1.-] which is distinct from the 2-enoyl-CoA reductase [EC 1.3.1.8] is demonstrated in beef liver. Substrates for the 4-enoyl-CoA reductase are acyl-CoA esters, which possess a 2,4-diene structure rather than those containing an isolated double bond in position 4. The 4-enoyl-CoA reductase is involved in the catabolism of cis-4-decenoyl-CoA. A reaction sequence for the degradation of cis-4-decenoyl-CoA to octanoyl-CoA is proposed which combines the 4-enoyl-CoA reductase with the classical .beta.-oxidation enzymes.