The effect of cytochrome c and its 'dimer' on electron transfer and energy transformation.
A preparation that contained cytochrome c, mainly in the form of its ;dimer', was studied and compared with native cytochrome c with respect to its ability to support electron transfer and energy transformation in cytochrome c-depleted rat liver mitochondria. When the depleted mitochondria were titrated with either cytochrome c or the ;dimer', the extent of coupling between respiration and phosphorylation was enhanced, as manifested by an increase in the P/O ratio. The ;dimer' was relatively ineffective as an electron carrier in the respiratory system, but it was as effective as cytochrome c in reconstitution of oxidative phosphorylation in depleted mitochondria. Addition of ;dimer' to the depleted mitochondria, in the presence of a low, non-saturating concentration of cytochrome c, increased the P/O ratio without concomitant stimulation of respiration. Both cytochrome c and the ;dimer' stimulated spontaneous swelling and electron transport-driven proton translocation in depleted mitochondria. The pattern of action of cytochrome c and its ;dimer' is in accord with the assumption that they affect an early step in energy conservation.
D000251:Adenosine Triphosphatases / Q000032:analysis; D000818:Animals; D003580:Cytochromes / Q000378:metabolism*; D004579:Electron Transport; D004735:Energy Transfer; D066298:In Vitro Techniques; D008930:Mitochondria, Liver / Q000378:metabolism; D010085:Oxidative Phosphorylation; D010101:Oxygen Consumption; D010759:Phosphorus Isotopes; D011108:Polymers; D011506:Proteins / Q000032:analysis; D051381:Rats
D003580:Cytochromes; D010759:Phosphorus Isotopes; D011108:Polymers; D011506:Proteins; D000251:Adenosine Triphosphatases