SUPEROXIDE RADICAL AND SUPEROXIDE DISMUTASE
SUPEROXIDE RADICAL AND SUPEROXIDE DISMUTASE
复制标题
DOI：
10.1021/ar50058a001
复制
发表时间：
1972-01-01
影响因子：
18.3
通讯作者：
FRIDOVICH, I
中科院分区：
文献类型：
--
作者：
FRIDOVICH, I
处于基态的分子氧含有两个不成对的电子并且具有顺磁性。因此，基态氧与外源电子对的相互作用面临自旋限制。因此，涉及基态氧的氧化反应很可能通过单电子步骤进行并涉及自由基中间体。 1 超氧自由基 (02-) 参与具有生物学意义的氧化作用，因此可以预期需氧细胞内存在针对这些自由基潜在毒性的防御机制。事实并非如此。相反，这些认识是逐渐实现的，是为偶然观察到的现象寻找解释的曲折道路的结果。对这些历史方面进行了简要总结。黄嘌呤氧化酶催化黄嘌呤氧化成尿酸盐，据观察，它会引发亚硫酸盐的氧化，并且只有在可氧化底物和氧同时存在的情况下才会发生氧化。 2 长期以来人们就知道亚硫酸盐的有氧氧化是通过自由基链式反应进行的，并且黄嘌呤氧化酶产生的O2~被发现是引发该链式反应的原因。 3-5 黄嘌呤氧化酶还能够催化黄嘌呤对细胞色素 c 的还原，但该过程被证明依赖于氧气的存在，6 和
Molecular oxygen, in theground state, contains two unpaired electrons and is paramagnetic. The inter-action of ground-state oxygen with an exogenous elec-tron pair is therefore faced with a spin restriction. Oxidation reactions involving oxygen in the ground state are hence likely to proceed by one-electron steps and to involve free-radicalintermediates. 1 Some involvement of superoxide radicals (02-) in oxidations of biological significance and the existence of a mechanism of defense against the potential toxicity of these radicals within aerobic cells might therefore have been anticipated. It was not. These realizations were, rather, reached gradually and as the result of traveling a tortuous path in search of explanations for fortuitously observed phenomena. These historical aspects are briefly summarized. Xanthine oxidase, which catalyzes the oxidation of xanthine to urate, was observed to initiate the oxida-tion of sulfite and did so only in thecombined presence of an oxidizable substrate and of oxygen. 2 The aerobic oxidation of sulfitehad long been known to proceed by a free-radical chain reaction and the 02~ generated by xanthine oxidase was found to be the agent responsible for initiation of this chain reaction. 3-5 Xanthine oxidase is also capable of catalyzing the reduction of cytochrome c by xanthine, but this process was shown to be dependent upon the presence of oxygen, 6 and