[Effect of inhibitors of microsomal hydroxylation on endogenous respiration of Torulopsis candida cells].

The effect of inhibitors of microsomal cytochrome P-450 on endogenous respiration and the redox state of components in the electron transport chain was studied in the cells of Torulopsis candida. SKP-525 A and methyrapone in the presence of preliminarily added cyanide (or antimycin A) almost completely inhibited endogenous respiration of the cells irrespective of the growth phase of the culture. The effect of these inhibitors on endogenous respiration and the reduction state of pyridine nucleotides, flavoproteins and cytochromes b, c and a + a3, at all of the studied growth phases, was similar to that of hydroxamic acids, the inhibitors of the mitochondrial alternative oxidase system. Contrary to their action on endogenous respiration of the cells at the exponential phase, both benzhydroxamic acid (BHA) and the inhibitors of microsomal hydroxylation, in the presence of rotenone, suppressed endogenous respiration of the cells taken at the stationary phase. Therefore, the interaction of the electron transport chains changed in the process of the cultural growth. Addition of BHA to the medium inhibited growth of the culture on glucose and biosynthesis of cytochrome P-450 in these cells. The culture did not grow on hexadecane in the presence of BHA. Apparently, hydroxamic acids can affect the operation of the microsomal monooxigenase system containing cytochrome P-450.