Delta super(3), Delta super(2)-Enoyl-CoA isomerases. Characterization of the mitochondrial isoenzyme in the rat

Delta super(3), Delta super(2)-Enoyl-CoA isomerase (EC 5.3.3.8), an obligatory auxiliary enzyme for the metabolism of double bonds at odd-numbered positions of fatty acids during their beta -oxidation, was studied in heart and livers of normal and clofibrate-treated rats. Hepatic peroxisomal and mitochondrial isoenzymes were separable by dye-ligand chromatography. The mitochondrial one was further purified to apparent homogeneity. An isomerase was also purified from heart muscle, a peroxisome-poor tissue. By immunoelectron microscopy the enzyme protein selected for purification was found to be mitochondrial both in liver and heart. The data are in accord with the notion of a dual location of the Delta super(3), Delta super(2)-enoyl-CoA isomerase. Mitochondrial origin of one of the isoenzymes and its tissue-specific induction by clofibrate were verified by immunochemistry and the identity of the peroxisomal one revealed by the chromatographic behavior of the proteins.