[Study of the reversible inactivation of the cyanide-resistant pathway of electron transfer in mitochondria of the yeast Candida lipolytica].

The study of reversible inactivation process of alternative pathway of electron transfer in cyanide-resistant mitochondria of C. lipolytica yeast was carried out. The appearance of sensitivity of respiration of cyanide-resistant mitochondria to cyanide and lowering of sensitivity of substrate oxidation to benzohydroxamic acid (the inhibitor of electron transfer along the alternative pathway) during the incubation was observed. The increase of temperature and the presence of magnesium ions in the incubation medium accelerates this process. The loss of cyanide resistance of respiration by mitochondria is not practically followed by the decrease of NADH-and alpha-glycerophosphatoxidase activity. Reactivation of cyanide resistance of respiration in incubated mitochondria is reached during washing them with the medium containing EDTA. The addition of magnesium ions into the washing medium prevents the reactivation process. On the basis of data obtained it is concluded that the relation between the respiratory chain and alternative oxidase is regulated by magnesium.