Superoxide dismutase amplifies organismal sensitivity to ionizing radiation.
Superoxide dismutase amplifies organismal sensitivity to ionizing radiation.
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发表时间：
1989-02
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通讯作者：
M. Scott;S. Meshnick;J. Eaton
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作者：
M. Scott;S. Meshnick;J. Eaton
虽然增加超氧化物歧化酶（SOD）的活性往往与增强细胞和生物体的抗氧化剂的挑战，这种酶的抗氧化剂的重要性进行了一些直接的测试。为了评估SOD在防御γ辐射中的重要性，我们采用了具有缺陷、正常和超常酶活性的大肠杆菌。令人惊讶的是，E.大肠杆菌的SOD活性会随着细菌SOD活性的增加而增加。细胞内SOD活性升高使E.大肠杆菌对辐射诱导的死亡率，而SOD缺陷型细菌表现出正常或降低的辐射敏感性。这种现象涉及活性氧物质的毒性效应;细菌SOD活性对厌氧条件下的辐射敏感性或其他非氧依赖性毒素（如紫外线辐射）的致死性没有影响。
Although increased superoxide dismutase (SOD) activity is often associated with enhanced resistance of cells and organisms to oxidant challenges, few direct tests of the antioxidant importance of this enzyme have been carried out. To assess the importance of SOD in defending against gamma-radiation, we employed Escherichia coli with deficient, normal, and super-normal enzyme activities. Surprisingly, the radiation sensitivity of E. coli actually increases as bacterial SOD activity increases. Elevated intracellular SOD activity sensitizes E. coli to radiation-induced mortality, whereas SOD-deficient bacteria show normal or decreased radiosensitivity. Toxic effects of activated oxygen species are involved in this phenomenon; bacterial SOD activity has no effect on radiation sensitivity under anaerobic conditions or on the lethality of other, non-oxygen-dependent, toxins such as ultraviolet radiation.