[Respiratory system of Endomyces magnusii. Properties of mitochondria from cells grown on glycerol].

Some peculiarities of oxidation of various substrates by tightly coupled highly energized mitochondria from the yeast Endomyces magnusii were studied. During cell growth on glycerol the formation of NADH and alpha-glycerophosphate in the hyaloplasm is paralleled with an adaptive synthesis of highly active dehydrogenases in the mitochondria. The dehydrogenases oxidize these substrates and are localized on the outer surface of the inner mitochondrial membrane. The reducing equivalents of the dehydrogenases enter the respiratory chain at the ubiquinone level by a shunt via the rotenone-sensitive site of the respiratory chain. Terminal oxidation of exogenous NADH, alpha-glycerophosphate and NAD-dependent substrates occurs in the cytochrome chain and is tightly coupled with phosphorylation. The ADP/O value is close to theoretical ones. Oxidation of succinate is partly mediated by alternate cyanide-resistant oxidase; the shunt-off of the electron flow between two alternate pathways is controlled by ADP. The tight coupling and theoretical efficiency of phosphorylation under succinate oxidation can take place only in the presence of salycyl hydroxamate, an alternate pathway inhibitor. A possible physiological role of alternate oxidase and the peculiarities of oxidation control at the individual substrate level are discussed.