title: Interactions between ubiquinones and vitamins in membranes and cells.
abstract: The interaction between ubiquinones and vitamin E was studied in the inner membranes of rat liver mitochondria, liposomes and human erythrocyte plasma membranes. Free radicals were produced by addition of exogenous oxidants, and their reaction with chromanols and ubiquinone was followed by ESR and HPLC. Membranes were made deficient in ubiquinone but sufficient in alpha-tocopherol and were reconstituted with added ubiquinone. With these membrane preparations it was shown that (i) in the inner mitochondrial membranes there is a requirements for ubiquinone in the enzymatic recycling of vitamin E; (ii) succinate-ubiquinone reductase incorporated in liposomes cannot protect vitamin E in the absence of ubiquinone and (iii) in human erythrocyte plasma membranes protection against the loss of vitamin E can be provided by NADH-cytochrome-b5-dependent enzymatic recycling. We conclude that ubiquinonols (ubisemiquinones) reduce vitamin E through electron transport.
authors.affiliation: Department of Molecular and Cell Biology, University of California, Berkeley 94720, USA.
authors.forename: A
authors.initials: A
authors.lastname: Constantinescu
authors.forename: J J
authors.initials: JJ
authors.lastname: Maguire
authors.forename: L
authors.initials: L
authors.lastname: Packer
mesh_terms: D000818:Animals; D002462:Cell Membrane / Q000378:metabolism*; D002839:Chromans / Q000493:pharmacokinetics; D002851:Chromatography, High Pressure Liquid; D004347:Drug Interactions; D004578:Electron Spin Resonance Spectroscopy; D004579:Electron Transport; D042963:Electron Transport Complex II; D004910:Erythrocyte Membrane / Q000378:metabolism; D005057:Eukaryotic Cells / Q000378:metabolism*; D005609:Free Radicals; D006801:Humans; D007425:Intracellular Membranes / Q000378:metabolism; D008081:Liposomes / Q000378:metabolism; D008930:Mitochondria, Liver / Q000378:metabolism; D009097:Multienzyme Complexes / Q000378:metabolism; D009243:NAD / Q000378:metabolism; D010088:Oxidoreductases / Q000378:metabolism; D051381:Rats; D013385:Succinate Dehydrogenase / Q000378:metabolism; D013386:Succinates / Q000378:metabolism; D019802:Succinic Acid; D014451:Ubiquinone / Q000378:metabolism*; D014810:Vitamin E / Q000378:metabolism*
chemical_list: C048427:2,2,5,7,8-pentamethylchroman; D002839:Chromans; D005609:Free Radicals; D008081:Liposomes; D009097:Multienzyme Complexes; D013386:Succinates; D009243:NAD; D014451:Ubiquinone; D014810:Vitamin E; D019802:Succinic Acid; D010088:Oxidoreductases; D042963:Electron Transport Complex II; D013385:Succinate Dehydrogenase