SUPEROXIDE-DRIVEN NAD(P)H OXIDATION INDUCED BY EDTA-MANGANESE COMPLEX AND MERCAPTOETHANOL
SUPEROXIDE-DRIVEN NAD(P)H OXIDATION INDUCED BY EDTA-MANGANESE COMPLEX AND MERCAPTOETHANOL
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DOI：
10.1016/0009-2797(90)90030-q
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发表时间：
1990-01-01
影响因子：
5.1
通讯作者：
ALDINUCCI, D
中科院分区：
文献类型：
--
作者：
PAOLETTI, F;MOCALI, A;ALDINUCCI, D
已经开发并表征了用于NAD（P）H氧化为生物活性NAD（P）+的纯化学系统。在生理pH下组合的适量EDTA、锰离子和巯基乙醇通过还涉及分子氧的链长诱导核苷酸氧化，其最终经历定量还原成过氧化氢。Mn 2+是活性所特别需要的，而EDTA和巯基乙醇都可以被类似物替代。当螯合剂与金属离子的最佳摩尔比为2：1时，生成的配位化合物具有催化巯基自氧化生成巯基自由基的活性。后者被分子氧进一步氧化成二硫化物，分子氧的单电子还原产生超氧自由基。超氧化物歧化酶（SOD）抑制硫醇氧化和氧消耗以及NAD（P）H的氧化（如果存在于混合物中）。根据反应的化学计量比，提出了一个初步的链长方案。在核苷酸氧化中有两个步骤显得特别重要：（a）NAD（P）的假定瞬时形成。（B）通过超氧化物氧化还原的复合物以保持硫醇氧化循环。
A purely chemical system for NAD(P)H oxidation to biologically active NAD(P)+ has been developed and characterized. Suitable amounts of EDTA, manganous ions and mercaptoethanol, combined at physiological pH, induce nucleotide oxidation through a chain length also involving molecular oxygen, which eventually undergoes quantitative reduction to hydrogen peroxide. Mn2+ is specifically required for activity, while both EDTA and mercaptoethanol can be replaced by analogs. Optimal molar ratios of chelator/metal ion (2 : 1) yield an active coordination compound which catalyzes thiol autoxidation to thiyl radical. The latter is further oxidized to disulfide by molecular oxygen whose one-electron reduction generates superoxide radical. Superoxide dismutase (SOD) inhibits both thiol oxidation and oxygen consumption as well as oxidation of NAD(P)H if present in the mixture. A tentative scheme for the chain length occurring in the system is proposed according to stoichiometry of reactions involved. Two steps appear of special importance in nucleotide oxidation (a) the supposed transient formation of NAD(P). from the reaction between NAD(P)H and thiyl radicals; (b) the oxidation of the reduced complex by superoxide to keep thiol oxidation cycling.