Enoyl CoA Isomerase - Enzyme Mechanism

Enzyme Mechanism

Enoyl-CoA isomerase is involved in the beta-oxidation, one of the most frequently used pathways in fatty acid degradation, of unsaturated fatty acids with double bonds at odd-numbered carbon positions. It does so by shifting the position of the double bonds in the acyl-CoA intermediates and converting 3-cis or trans-enoyl-CoA to 2-trans-enoyl-CoA. Since the key step in the degradation of fatty acids with double bonds at even-numbered carbon positions also produces 3-trans-enoyl-CoA in mammals and yeasts, enoyl-CoA isomerase is technically required for their metabolism as well. The reaction mechanism is detailed in Figure 1, and the base that initiates the isomerization and NH groups that stabilize the intermediate are located on the active site of enoyl-coA isomerase.

As it functions in the step immediately preceding the actual beta-oxidation and forms a double bond extending from the beta-carbon (position 2), enoyl-CoA isomerase is involved in both the NADPH-dependent and NADPH-independent pathways of beta-oxidation. The double bond serves as the target of oxidation and carbon-to-carbon bond cleavage, thereby shortening the fatty acid chain.