ISOLATION OF ACYL-COA DERIVATIVES AS PRODUCTS OF PARTIAL REACTIONS IN THE MICROSOMAL CHAIN ELONGATION OF FATTY-ACIDS

An analysis of overall chain elongation, condensation, β-hydroxyacyl-CoA dehydrase and 2-trans enoyl-CoA reductase reactions, using the appropriate CoA derivatives as substrates which are required in the microsomal chain elongation of both palmitoyl-CoA and 6, 9-octadecadienoyl-CoA, demonstrated that in each instance, the products of these reactions were the CoA derivatives. Reverse dehydrase reactions run with 2-trans enoyl-CoA derivatives as substrates, in the absence of NADPH, revealed that the product was the β-hydroxy-acyl-CoA. In the presence of NADPH, incubations with β-hydroxyacyl-CoA demonstrated that both the 2-trans derivatives and the α, β-saturated product were recovered as their CoA derivatives. These latter findings are more consistent with the involvement of discrete dehydrase and 2-trans-enoyl-CoA reductase enzymes rather than a single protein catalyzing two reactions. © 1979.