Effects of amino acid replacements in yeast iso-1 cytochrome c on heme accessibility and intracomplex electron transfer in complexes with cytochrome c peroxidase.
Effects of amino acid replacements in yeast iso-1 cytochrome c on heme accessibility and intracomplex electron transfer in complexes with cytochrome c peroxidase.
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酵母 iso-1 细胞色素 c 中的氨基酸替换对细胞色素 c 过氧化物酶复合物中血红素可及性和复合物内电子转移的影响。
DOI：
10.1021/bi00412a035
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发表时间：
1988
期刊：
影响因子：
2.9
通讯作者：
Tollin,G
中科院分区：
文献类型：
--
作者：
Hazzard,JT;McLendon,G;Cusanovich,MA;Das,G;Sherman,F;Tollin,G
修订稿于 1988 年 2 月 2 日收到摘要：酵母 iso-1 细胞色素 c 的野生型和几个位点特异性突变体（Arg-13—* He、Gin-16—*· Ser、Gin-16-*· Lys、Lys-27-*· Gin、Lys-72-* Asp）的还原动力学，均为游离型和与酵母细胞色素 c 形成 1:1 复合物 已经研究了游离黄素半醌的过氧化物酶。还研究了在低(8 mM)和高(275 mM)离子强度下从亚铁细胞色素c到H 2 O 2 氧化的过氧化物酶的分子内单电子转移。静电稳定复合物内细胞色素化学的可及性以及低离子强度和高离子强度下分子内电子转移的速率常数高度依赖于蛋白质-蛋白质界面处存在的特定氨基酸。重要的是，被认为对电子转移复合物的定向和/或稳定很重要的Arg或Lys残基被不带电的氨基酸取代导致电子转移速率增加。在所有情况下，离子强度从 8 mM 增加到 275 mM 也会导致分子内电子转移速率常数增加。结果表明，静电稳定的 1:1 复合物并未针对电子转移进行优化，并且通过中和关键的带正电残基，或通过增加离子强度从而掩盖离子相互作用，两种蛋白质可以自行定向以形成更有效的电子转移复合物。
Revised Manuscript Received February 2, 1988 abstract: The kinetics of reduction of wild type and several site-specific mutants of yeast iso-1 cytochrome c (Arg-13—* He, Gin-16—*· Ser, Gin-16-*· Lys, Lys-27-*· Gin, Lys-72-* Asp), both freeand in 1: 1 complexes with yeast cytochrome c peroxidase, by free flavin semiquinones have been studied. Intramolecular one-electron transferfrom the ferrous cytochromes c to the H202-oxidized peroxidase at both low (8 mM) and high (275 mM) ionic strengths was also studied. The accessibility of the cytochrome c heme within the electrostatically stabilized complex and the rate constants for intramolecular electron transfer at both low and high ionic strength are highly dependent on the specific amino acids present at the protein-protein interface. Importantly, replacement by uncharged amino acids of Arg or Lys residues thought to be important in orientation and/or stabilization of the electron-transfer complex resulted in increased rates of electron transfer. In all cases, an increase in ionic strengths from 8 to 275 mM also produced increased intramolecular electron-transfer rate constants. The results suggest that the electrostatically stabilized 1: 1 complex is not optimized for electron transfer and that by neutralization of key positively charged residues, or by an increase in the ionic strength thereby masking the ionic interactions, the two proteins can orient themselves to allow the formation of a more efficient electron-transfer complex.