Identification of deoxy-alpha-tocopherolquinol as another endogenous electron donor for biohydrogenation

Solvent extracts of Butyrivibrio fibrisolvens contain 2-[3, 7, 11, 15-tetramethylhexadecyl]-3, 5, 6-trimethyl-benzoquinol (deoxy-alpha-tocopherolquinol) that can serve as an alternate electron donor for alpha-tocopherolquinol for the biohydrogenation of cis-9, trans-11-octadecadienoate. In addition, the cell extracts contain deoxy-alpha-tocopherolquinone. This compound arises metabolically from alpha-tocopherolquinone via dehydration to trimethylphytylbenzoquinone followed by hydrogenation to deoxy-alpha-tocopherolquinone. Although the hydrogenation of the isoprene double bond and the conjugated fatty acid both use NADH as the primary reductant, the two reactions appear to be catalyzed by different enzymes.