[Control of the alternative pathway of electron transfer in mitochondria of the yeast Candida lipolytica].

The dependence of the activity of the alternative cyanide-resistant electron transfer pathway in mitochondria of the yeast Candida lipolytica on the functional state of the main phosphorylating respiratory chain was studied. Oxidation of NAD-linked substrates both in active or uncoupled and controlled states by cyanide-resistant mitochondria was shown to be performed solely by the main respiratory chain. Succinate or alpha-glycerophosphate in the active or uncoupled state of the respiratory chain are oxidized solely by the main respiratory chain, whose changes in the controlled state are accompanied by activation of the alternative pathway of electron transfer. Exogenous NADH is oxidized both in active and controlled states of the respiratory chain by the main respiratory chain and the alternative pathway simultaneously. The transition of the respiratory chain from active to controlled state is followed therewith by an additional activation of the alternative pathway. It was concluded that the alternative pathway contribution to the total oxygen consumption by mitochondria is controlled by the activity of the main respiratory chain. The alternative pathway accomplishes the transfer of reducing equivalents excessive for the main respiratory chain.