SOME ONE ELECTRON REDUCTION PRODUCTS OF FLAVIN ANALOGS: CYANOISOALLOXAZINES AND DEAZAISOALLOXAZINES
SOME ONE ELECTRON REDUCTION PRODUCTS OF FLAVIN ANALOGS: CYANOISOALLOXAZINES AND DEAZAISOALLOXAZINES
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黄素类似物的一种电子还原产物：氰基异恶嗪和脱氮异恶嗪
DOI：
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发表时间：
1979
期刊：
影响因子：
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通讯作者：
T. C. Bruice
中科院分区：
文献类型：
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作者：
G. Tollin;R. Chan;Thomas R. Malefyt;T. C. Bruice
摘要- 8‐氰- 10‐甲基- 3‐磺丙基异alloxazine (I)在酸性和碱性条件下均测量了8‐氰- 10‐甲基- 3‐磺丙基异alloxazine (I)自由基形式的电子自旋共振（EPR）谱。EPR谱与未取代的异四氧嘧啶相似。没有任何迹象表明氰化氮会导致超细分裂。在EDTA存在下，在碱性pH下激光光解I产生两种自由基。其中一种通过一阶过程快速衰变生成稳定的自由基。这种衰变的速率取决于初始黄素浓度，因此表明自由基与氧化的异alloxazine发生反应。自由基与添加氧化剂（O2、铁氰化物）的反应速率以及稳定自由基形成的pH依赖性表明，快速衰变的自由基是I的阴离子自由基，而稳定自由基是通过与氧化的黄素反应形成的。在酸性pH下激光光解I，以及在酸性或碱性pH下激光光解8 -氰基- 5 -二氮杂-异alloxazine，都不会产生稳定的自由基。在激光光解作用下，二氮杂异alloxazines完全不产生自由基瞬变。
Abstract— 8‐Cyanoisoalloxazines have been previously shown to form highly stable radical species at basic pH. We have measured the electron spin resonance (EPR) spectra of the radical forms of 8‐cyano‐10‐methyl‐3‐sulfopropylisoalloxazine (I) at both acidic and basic pH. In both cases. the EPR spectra are similar to those obtained from unsubstituted isoalloxazines. with no indication of hyperfine splitting due to the cyano nitrogen. Laser photolysis of I in the presence of EDTA at basic pH generates two radical species. One of these decays rapidly by a first‐order process to produce thc stable radical. The rate of this decay depends upon the initial flavin concentration, thus suggesting a reaction of the radical with oxidized isoalloxazine. The rates of reaction of the radical species with added oxidants (O2, ferricyanide), and the pH‐dependence of stable radical formation, indicate that the rapidly‐decaying species is the anion radical of I, and that the stable radical is formed by its reaction with oxidized flavin. Laser photolysis of I at acidic pH, as well as of 8‐cyano‐5‐deaza‐isoalloxazine at acidic or basic pH, does not generate stable radical species. I‐Deazaisoalloxazines do not give radical transients at all upon laser photolysis.