Lee J H, Choi I Y, Kil I S, Kim S Y, Yang E S, Park J W
Department of Biochemistry, College of Natural Sciences, Kyungpook National University, 702-701, Taegu, South Korea.
Biochim Biophys Acta. 2001 May 3;1526(2):191-8. doi: 10.1016/s0304-4165(01)00126-x.
The protective role of superoxide dismutases (SODs) against ionizing radiation, which generates reactive oxygen species (ROS) harmful to cellular function, was investigated in the wild-type and in mutant yeast strains lacking cytosolic CuZnSOD (sod1Delta), mitochondrial MnSOD (sod2Delta), or both SODs (sod1Deltasod2Delta). Upon exposure to ionizing radiation, there was a distinct difference between these strains in regard to viability and the level of protein carbonyl content, which is the indicative marker of oxidative damage to protein, intracellular H2O2 level, as well as lipid peroxidation. When the oxidation of 2',7'-dichlorofluorescin was used to examine the hydroperoxide production in yeast cells, the SOD mutants showed a higher degree of increase in fluorescence upon exposure to ionizing radiation as compared to wild-type cells. These results indicated that mutants deleted for SOD genes were more sensitive to ionizing radiation than isogenic wild-type cells. Induction and inactivation of other antioxidant enzymes, such as catalase, glucose 6-phosphate dehydrogenase, and glutathione reductase, were observed after their exposure to ionizing radiation both in wild-type and in mutant cells. However, wild-type cells maintained significantly higher activities of antioxidant enzymes than did mutant cells. These results suggest that both CuZnSOD and MnSOD may play a central role in protecting cells against ionizing radiation through the removal of ROS, as well as in the protection of antioxidant enzymes.
超氧化物歧化酶（SODs）对电离辐射具有保护作用，电离辐射会产生活性氧（ROS），对细胞功能有害。本研究在野生型酵母菌株以及缺乏胞质铜锌超氧化物歧化酶（sod1Delta）、线粒体锰超氧化物歧化酶（sod2Delta）或两种超氧化物歧化酶（sod1Deltasod2Delta）的突变酵母菌株中展开。暴露于电离辐射后，这些菌株在存活率、蛋白质羰基含量水平（蛋白质氧化损伤的指示标记）、细胞内过氧化氢水平以及脂质过氧化方面存在明显差异。当使用2',7'-二氯荧光素的氧化来检测酵母细胞中氢过氧化物的产生时，与野生型细胞相比，超氧化物歧化酶突变体在暴露于电离辐射后荧光增加程度更高。这些结果表明，缺失超氧化物歧化酶基因的突变体比同基因野生型细胞对电离辐射更敏感。在野生型和突变体细胞暴露于电离辐射后，均观察到其他抗氧化酶如过氧化氢酶、葡萄糖6-磷酸脱氢酶和谷胱甘肽还原酶的诱导和失活。然而，野生型细胞的抗氧化酶活性显著高于突变体细胞。这些结果表明，铜锌超氧化物歧化酶和锰超氧化物歧化酶可能在通过清除活性氧保护细胞免受电离辐射以及保护抗氧化酶方面发挥核心作用。
