Biohydrogenation of unsaturated fatty acids. Purification and properties of cis-9,trans-11-octadecadienoate reductase.

The enzyme catalyzing the second step in the biohydrogenation pathway of linoleic acid by Butyrivibrio fibrosolvens cis-9,trans-11-octadecadienoate reductase has been purified to near homogeneity. It has a molecular weight of 60,000 and appears to be a single subunit. The purified enzyme contains 2 mol of iron, 10 mol of fucose, and 12 mol of galactose per 60,000 g. The iron, but not the carbohydrate, is required for enzymatic activity. Phosphatidylethanolamine was also found to be associated with the purified enzyme. Unlike the cell extract that can reduce the double bond of the fatty acid with NADH or alpha-tocopherolquinol as a reductant, the purified enzyme can utilize only alpha-tocopherolquinol. This indicates that another component of the reduction system exists that couples the production of alpha-tocopherolquinol to the oxidation of NADH.