A function for the vitamin E metabolite alpha-tocopherol quinone as an essential enzyme cofactor for the mitochondrial fatty acid desaturases

A critical analysis of the changes in fatty acid patterns and their metabol ism elicited by vitamin E deficiency leads to the proposal that a major rol e of dietary RRR-alpha-tocopherol (alpha-TOC) is as an enzymatic precursor of alpha-tocopberolquinone (alpha-TQ) whose semiquinone radical functions a s an essential enzyme cofactor for the fatty acid desaturases of the recent ly elucidated carnitine-dependent, channeled, mitochondrial desaturation-el ongation pathway; a detailed mechanism for its function is proposed. Pathop hysiological states produced by vitamin E deficiency and alpha-TOC transfer protein defects, such as ataxia, myopathy, retinopathy, and sterility are proposed to develop from the effects of impaired alpha-TQ-dependent desatur ases and the resulting deficiency of their polyenoic fatty acid products. ( C) 1999 Federation of European Biochemical Societies.