Superoxide dismutase (SOD) is an essential enzyme protecting cells against oxidative stress. However, its specific role under different conditions is not clear. To study the possible role of SOD in the cell during respiration, Saccharomyces cerevisiae single and double mutants with inactivated SOD1 and/or SOD2 genes growing on ethanol as an energy and carbon source were used. Activities of antioxidant and associated enzymes as well as the level of protein carbonyls were measured. SOD activity was significantly higher in a Mn-SOD deficient strain than that in the wild-type parental strain, but significantly lower in a Cu, Zn-SOD mutant. A strong positive correlation between SOD and catalase activities (R(2) = 0.99) shows possible protection of catalase by SOD from inactivation in vivo and/or decrease in catalase activity because of lower H(2)O(2) formation in the mutant cells. SOD deficiency resulted in a malate dehydrogenase activity increase, whereas glucose-6-phosphate dehydrogenase (G6PDH) activity was lower in SOD-deficient strains. Linear and non-linear positive correlations between SOD and isocitrate dehydrogenase activities are discussed. No changes in the activity of glutathione reductase and protein carbonyl levels support the idea that SOD-deficient cells are not exposed to strong oxidative stress during exponential growth of yeast cultures on ethanol.

中文翻译：

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在乙醇上的生长导致啤酒酵母对编码超氧化物歧化酶的基因失活产生协调的反应。

超氧化物歧化酶（SOD）是保护细胞抵抗氧化应激的重要酶。但是，其在不同条件下的具体作用尚不清楚。为了研究SOD在呼吸过程中在细胞中的可能作用，使用了酿酒酵母单和双突变体，这些突变体具有在乙醇上作为能量和碳源生长的失活的SOD1和/或SOD2基因。测量抗氧化剂和相关酶的活性以及蛋白质羰基的水平。Mn-SOD缺陷菌株中的SOD活性明显高于野生型亲本菌株，但Cu，Zn-SOD突变体中的SOD活性则显着降低。SOD和过氧化氢酶活性之间有很强的正相关性（R（2）= 0。图99）显示了SOD对过氧化氢酶的可能的保护，使其在体内失活和/或由于突变细胞中较低的H（2）O（2）形成而导致过氧化氢酶活性降低。SOD缺乏导致苹果酸脱氢酶活性增加，而SOD缺乏菌株的6磷酸葡萄糖磷酸脱氢酶（G6PDH）活性较低。讨论了SOD与异柠檬酸脱氢酶活性之间的线性和非线性正相关。谷胱甘肽还原酶的活性和蛋白质羰基水平没有变化，这支持以下观点：在酵母培养物在乙醇上以指数方式生长期间，SOD缺陷型细胞不会暴露于强氧化应激。讨论了SOD与异柠檬酸脱氢酶活性之间的线性和非线性正相关。谷胱甘肽还原酶的活性和蛋白质羰基水平没有变化，这支持以下观点：在酵母培养物在乙醇上以指数方式生长期间，SOD缺陷型细胞不会暴露于强氧化应激。讨论了SOD与异柠檬酸脱氢酶活性之间的线性和非线性正相关。谷胱甘肽还原酶的活性和蛋白质羰基水平没有变化，这支持以下观点：在酵母培养物在乙醇上以指数方式生长期间，SOD缺陷型细胞不会暴露于强氧化应激。