An increase in Brestan concentration in nutrient media decreased the content of protein, phosphorus, total ribonucleic acid, activity of pyruvate carboxylase and isocitrate lyase in cells of Saccharomyces cerevisiae parent strain and respiratory deficient (RD) mutant while the trehalose content increased. The respiration quotient value for the RD mutant was higher than for the parent strain. The RD mutant lacked cytochrome aa3; cytochrome c and b contents were lower than those of the parent strain.