铜锌超氧物歧化酶与过氧化氢反应中羟自由基的形成

THE GENERATION OF HYDROXYL RADICALS FROM COPPER, ZINC SUPEROXIDE DISMUTASE REACTING WITH H2O2

摘要:

应用脱氧核糖降解法研究了离体条件下Cu，Zn-SOD与H₂O₂反应产生·OH，并对其机理进行了探讨。H₂O₂可使Cu，Zn-SOD失活，在失活过程中有·OH产生，甲酸钠和苯甲酸钠均能不同程度地保护Cu，Zn-SOD和降低H2O2与Cu，Zn-SOD反应中·OH的产额；热失活SOD也可和H₂O₂反应生成·OH，且效能高于活性Cu，Zn-SOD；用螫合剂脱去Cu，Zn-SOD的金属辅基后，脱辅基的SOD蛋白不能和H₂O₂反应产生·OH；Cu²⁺和H₂O₂反应产生·OH的效率很高，而Zn²⁺产生·OH的效率很低。实验结果提示Cu，Zn－SOD与H₂O₂反应产生的·OH可能是SOD活性中心的Cu²⁺与H₂O₂发生Fenton反应的结果．

Abstract:

The generation of .OH from Cu,Znroontaining superoxide dismutase (CuZn-SOD) reacting with H₂O₂ was studied by using deoxyribose degradation method in which deoxyribose reacts with. OH to release TBA-reactive compounds. Cu, ZnSOD could be inactivated by H₂O₂, during which. OH was produced. Formate and benzoate,scavengers of. OH, could partially protect Cu,Zn-SOD against inaCtivation by H₂O₂, and could inhibit the generation of. OH from Cu, Zn-SOD reacting with H₂O₂. Heat inactivated Cu,Zn-SOD could also react with H₂O₂ to generate. OH, and it was more effective in generating .OH than the active Cu,Zn-SOD. Apoprotein of Cu,ZnSOD did not catalyze .OH generation from H₂O₂. Zn²⁺ could hardly react with H₂O₂ to form 'OH, whereas Cu²⁺ was highly effective in generating. OH through Fenton reaction. These observations suggest that the generation of. OH from Cu,Zn-SOD reacting with Hood is due to the Fenton reaction between H₂O₂, and Cu²⁺ in the active center of Cu,Zn-SOD.