Electron transport chain of Saccharomyces cerevisiae mitochondria is inhibited by H2O2 at succinate-cytochrome c oxidoreductase level without lipid peroxidation involvement.
The deleterious effects of H202 on the electron transport chain of yeast mitochondria and on mitochondrial lipid peroxidation were evaluated. Exposure to H2O2 resulted in inhibition of the oxygen consumption in the uncoupled and phosphorylating states to 69% and 65%, respectively. The effect of H2O2 on the respiratory rate was associated with an inhibition of succinate-ubiquinone and succinate-DCIP oxidoreductase activities. Inhibitory effect of H2O2 on respiratory complexes was almost completely recovered by beta-mercaptoethanol treatment. H2O2 treatment resulted in full resistance to Qo site inhibitor myxothiazol and thus it is suggested that the quinol oxidase site (Qo) of complex III is the target for H2O2. H2O2 did not modify basal levels of lipid peroxidation in yeast mitochondria. However, H2O2 addition to rat brain and liver mitochondria induced an increase in lipid peroxidation. These results are discussed in terms of the known physiological differences between mammalian and yeast mitochondria.
Cortés-Rojo
Christian
C
Instituto de Investigaciones Químico-Biológicas, Universidad Michoacana de San Nicolás de Hidalgo, Morelia, Mich., México.
Calderón-Cortés
Elizabeth
E
Clemente-Guerrero
Monica
M
Manzo-Avalos
Salvador
S
Uribe
Salvador
S
Boldogh
Istvan
I
Saavedra-Molina
Alfredo
A
D000818:Animals; D001921:Brain / Q000187:drug effects / Q000378:metabolism; D004579:Electron Transport / Q000187:drug effects; D045222:Electron Transport Chain Complex Proteins / Q000378:metabolism*; D004789:Enzyme Activation / Q000187:drug effects; D006861:Hydrogen Peroxide / Q000494:pharmacology*; D015227:Lipid Peroxidation / Q000187:drug effects / Q000502:physiology*; D008928:Mitochondria / Q000187:drug effects* / Q000378:metabolism; D008930:Mitochondria, Liver / Q000187:drug effects / Q000378:metabolism; D051381:Rats; D012441:Saccharomyces cerevisiae / Q000187:drug effects / Q000378:metabolism*; D013384:Succinate Cytochrome c Oxidoreductase / Q000378:metabolism / Q000502:physiology*
D045222:Electron Transport Chain Complex Proteins; D006861:Hydrogen Peroxide; D013384:Succinate Cytochrome c Oxidoreductase