Biosynthesis of superoxide dismutase and catalase inSaccharomyces cerevisiae: effects of oxygen and cytochromec deficiency

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Abstract
Two strains ofSaccharomyces cerevisiae were used to study the synthesis of superoxide dismutase. One strain (cytochromec-deficient) contained 5–10% of the normal amounts of total cytochromec, while the other strain was a wild type. The cytochromec-deficient mutant had lower specific growth rate, growth yield, and oxygen uptake than the wild type. The superoxide dismutase and catalase activities, in both strains, were significantly lower under anaerobic than under aerobic conditions. Furthermore, under aerobic conditions the mutant contained higher levels of superoxide dismutase than the wild type which may be attributed to the higher intracellular flux of superoxide radicals caused by the cytochromec deficiency. The mutant also showed a lower level of catalase which was due to glucose repression.