β‐Oxidation of unsaturated fatty acids in humans Isoforms of Δ3, Δ2‐enoyl‐CoA isomerase

Abstract

This investigation was undertaken in order to elucidate the human enzymes which participate in metabolism of the double bonds of unsaturated fatty acids during, β-oxidation. The results indicate that the human monofunctional Δ3, Δ2-enoyl-CoA isomerase (EC 5.3.3.8) with the native Mr of 70,000 differed significantly from its rat counterpart [Palosaari et al. (1990) J. Biol. Chem. 265, 3347–3353]; the isoelectric point of the human isoform was over three pH-units more acidic, it showed different chromatographic behaviour, the human enzyme did not show any clear-cut substrate chain-length specificity and only a weak immunological cross-reactivity was detected with the antibody to rat liver mitochondrial short-chain enzyme. This explains the failure of attempts to apply the rat data directly to human beings. Another isomerase activity from human liver was found to be a part of the isomerase-hydratase-dehydrogenase polypeptide showing immunological cross-reactivity with the previously characterized peroxisomal multifunctional enzyme (MFE) from rat liver