[Effect of detergents on the main respiratory chain and cyanide-resistant pathway of electron tranfer of Candida lipolytica yeast mitochondria].

Effects of detergents--triton X-100 and deoxycholate--on the main respiratory chain and cyanide-resistant electron transfer pathway in the mitochondria of Candida lipolytica yeast were studied. Triton X-100 and deoxycholate were shown to completely inhibit the activity of alternative oxidase at concentrations of 0.7 and 1.2 mM, respectively. At these concentrations the detergents did not inhibit the activity of the main respiratory chain. The inhibiting effect of triton X-100 was exerted both in the presence of Mg2+ and without them, whereas the inhibiting action of deoxycholate was observed in the presence of Mg2+. The addition of asolektine in the presence of Mg2+ prevented the inhibiting effect of detergents. These data lead us to the conclusion that inhibition of electron transfer through the alternative pathway is caused by separation of alternative oxidase from the main respiratory chain with the disturbance of structural integrity of inner mitochondrial membrane under the action of detergents. Inhibition of electron transfer in the alternative pathway does not decrease the rate of oxygen consumption by mitochondria. Therefore, the main respiratory chain in the presence of detergents can provide for transfer of all reducing equivalents which were earlier transferred both by the respiratory chain itself and by alternative oxidase.