Stereoselective Photoinduced Electron-Transfer Reactions of Zinc Myoglobin with Optically Active Viologens.
Stereoselective Photoinduced Electron-Transfer Reactions of Zinc Myoglobin with Optically Active Viologens.
复制标题
锌肌红蛋白与光学活性紫罗碱的立体选择性光诱导电子转移反应。
DOI：
10.1021/ic970108o
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发表时间：
1997
影响因子：
4.6
通讯作者：
Tomoko Hara
中科院分区：
文献类型：
--
作者：
K. Tsukahara;C. Kimura;J. Kaneko;Kaya Abe;M. Matsui;Tomoko Hara
在25℃、pH 7.0(0.01M磷酸盐缓冲液)和不同离子强度的条件下，研究了锌取代肌红蛋白与光学活性紫精和双紫精之间的光诱导电子转移反应。锌肌红蛋白的激发三重态被光学活性紫精的(S，S)异构体优先猝灭，在0.02M的离子强度下，猝灭速率常数和反电子转移速率常数k((S，S))/k((R，R))的比值都在1.1~1.5之间，取代基的顺序为萘基>；苯基>；/=环己基。立体选择性随离子强度的增加而降低。紫精取代基团的立体体积可能会更有效地诱导锌肌红蛋白的构象变化，这是由于萘基与锌肌红蛋白多肽链之间的空间排斥作用。
Photoinduced electron-transfer reactions between zinc-substituted myoglobin and optically active viologens and bisviologens, containing ((naphthyl-, ((phenyl-, and ((cyclohexyl)ethyl)carbamoyl)methyl groups, have been studied at 25 degrees C, pH 7.0 (a 0.01 M phosphate buffer), and various ionic strengths. The excited triplet state of zinc myoglobin was preferentially quenched by (S,S)-isomers of optically active viologens; both ratios of the quenching rate constants and back-electron-transfer rate constants, k((S,S))/k((R,R)), range from 1.1 to 1.5 at an ionic strength of 0.02 M with the order naphthyl > phenyl >/= cyclohexyl for the substituents. Stereoselectivity decreased with increasing ionic strengths. The steric bulk of the substituents of viologen may induce the conformational change of zinc myoglobin more effectively due to the steric repulsion between naphthyl groups and the polypeptide chain of zinc myoglobin.