title: Oxidation and reduction of exogenous cytochrome c by the activity of the respiratory chain.
abstract: Oxidation of exogenous NADH by isolated rat liver mitochondria is generally accepted to be mediated by endogenous cytochrome c which shuttles electrons from the outer to the inner mitochondrial membrane. More recently it has been suggested that, in the presence of added cytochrome c, NADH oxidation is carried out exclusively by the cytochrome oxidase of broken or damaged mitochondria. Here we show that electrons can be transferred in and out of intact mitochondria. It is proposed that at the contact sites between the inner and the outer membrane, a "bi-trans-membrane" electron transport chain is present. The pathway, consisting of Complex III, NADH-b5 reductase, exogenous cytochrome c and cytochrome oxidase, can channel electrons from the external face of the outer membrane to the matrix face of the inner membrane and viceversa. The activity of the pathway is strictly dependent on both the activity of the respiratory chain and mitochondrion integrity.
authors.affiliation: Department of Biochemistry and Molecular Biology, University of Bari, Italy.
authors.forename: N E
authors.initials: NE
authors.lastname: Lofrumento
authors.forename: D
authors.initials: D
authors.lastname: Marzulli
authors.forename: L
authors.initials: L
authors.lastname: Cafagno
authors.forename: G
authors.initials: G
authors.lastname: La Piana
authors.forename: T
authors.initials: T
authors.lastname: Cipriani
mesh_terms: D000244:Adenosine Diphosphate / Q000494:pharmacology; D000818:Animals; D002259:Carbonyl Cyanide p-Trifluoromethoxyphenylhydrazone / Q000494:pharmacology; D003574:Cytochrome c Group / Q000378:metabolism*; D004579:Electron Transport / Q000187:drug effects; D066298:In Vitro Techniques; D008297:Male; D008930:Mitochondria, Liver / Q000187:drug effects / Q000378:metabolism; D009243:NAD / Q000378:metabolism; D010084:Oxidation-Reduction; D051381:Rats; D011919:Rats, Inbred Strains
chemical_list: D003574:Cytochrome c Group; D009243:NAD; D002259:Carbonyl Cyanide p-Trifluoromethoxyphenylhydrazone; D000244:Adenosine Diphosphate