ONE-ELECTRON-TRANSFER REACTIONS IN BIOCHEMICAL SYSTEMS .5. DIFFERENCE IN MECHANISM OF QUINONE REDUCTION BY NADH DEHYDROGENASE AND NAD(P)H DEHYDROGENASE (DT-DIAPHORASE)
ONE-ELECTRON-TRANSFER REACTIONS IN BIOCHEMICAL SYSTEMS .5. DIFFERENCE IN MECHANISM OF QUINONE REDUCTION BY NADH DEHYDROGENASE AND NAD(P)H DEHYDROGENASE (DT-DIAPHORASE)
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DOI：
10.1016/0005-2728(70)90220-3
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发表时间：
1970-01-01
期刊：
影响因子：
--
通讯作者：
YAMAZAKI, I
中科院分区：
文献类型：
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作者：
IYANAGI, T;YAMAZAKI, I
线粒体NADH脱氢酶催化醌的单电子还原。由此形成的半醌具有其自由阴离子自由基的超精细结构，并且被认为与酶分离。在合适的电子受体存在的情况下，电子从半醌转移到受体。菠菜铁氧化还原素- nadp还原酶还原醌的机制与NADH脱氢酶还原醌的机制相同。另一方面，由肝溶部分制备的NAD(P)H脱氢酶（DT-diaphorase）催化了典型的双电子还原，如苯甲酸醌和2-甲基-1,4-萘醌。使用配备流动装置的电子自旋共振谱仪和使用一组适当的电子受体，很容易区分醌的单电子和双电子还原机制。结果表明，黄酮类化合物与氧的还原反应可分为单电子反应、双电子反应和混合型反应三大类。
The mitochondrial NADH dehydrogenase catalyzes a one-electron reduction of quinones. Semiquinones thus formed have the hyperfine structures of their free anion radicals and are suggested to be detached from the enzyme. In the presence of suitable electron acceptors electron transfer occurs from the semiquinone to the acceptor. The mechanism of quinone reduction by spinach ferredoxin-NADP reductase is the same as that by the NADH dehydrogenase.On the other hand, the NAD(P)H dehydrogenase (DT-diaphorase) prepared from liver soluble fraction catalyzes a typical two-electron reduction of quinones such asp-benzoquinone and 2-methyl-1,4-naphthoquinone. The mechanisms of one-electron and two-electron reduction of quinones are readily distinguishable by the use of an electron spin resonance spectrometer equipped with a flow apparatus and also by the use of an appropriate set of electron acceptors.It is concluded that the reduction of quinones and oxygen by flavoproteins falls into three mechanistic categories: one-electron, two-electron and mixed-type reactions.