Mg(2+) induces intermembrane electron transport by cytochrome c desorption in mitochondria with the ruptured outer membrane.
The mechanism of external NADH oxidation in rat liver mitochondria is not clear yet, but it evidently includes the intermembrane electron transport (IMET). We showed that Mg(2+) significantly stimulated IMET insensitive to rotenone-antimycin A-myxothiazol in mitochondria with the hypotonically damaged outer membrane, even in the absence of exogenous cytochrome c. This effect was more specific than simply ionic strength increase. Direct evidence for cytochrome c desorption from mitochondrial membranes under 4 mM Mg(2+) influence was obtained to explain the stimulatory effect of Mg(2+) on external NADH oxidation that was coupled to the inner membrane potential generation. Obtained data suggest that cytochrome b(5) is normally oriented towards the cytosol in the outer membrane, and can be accessible for endogenous cytochrome c reduction only through the outer membrane rupture or permeabilization, to activate external NADH oxidation.
Lemeshko
V V
VV
Department of Physics, National University of Colombia, Medellin Branch, AA 3840, Medellin, Colombia. vvasilie@perseus.unalmed.edu.co
D000818:Animals; D000968:Antimycin A / Q000494:pharmacology; D003574:Cytochrome c Group / Q000378:metabolism*; D015786:Cytochromes b5 / Q000378:metabolism; D004579:Electron Transport; D005470:Fluorometry; D007038:Hypotonic Solutions / Q000494:pharmacology; D066298:In Vitro Techniques; D007425:Intracellular Membranes / Q000378:metabolism*; D008274:Magnesium / Q000378:metabolism*; D008689:Methacrylates; D008930:Mitochondria, Liver / Q000378:metabolism*; D009243:NAD / Q000378:metabolism; D010084:Oxidation-Reduction; D010539:Permeability; D051381:Rats; D012402:Rotenone / Q000494:pharmacology; D013844:Thiazoles / Q000494:pharmacology; D014475:Uncoupling Agents / Q000494:pharmacology
D003574:Cytochrome c Group; D007038:Hypotonic Solutions; D008689:Methacrylates; D013844:Thiazoles; D014475:Uncoupling Agents; D012402:Rotenone; D009243:NAD; D000968:Antimycin A; C030517:myxothiazol; D015786:Cytochromes b5; D008274:Magnesium