Cytochrome b562 variants: a library for examining redox potential evolution.
Cytochrome b562 variants: a library for examining redox potential evolution.
复制标题
细胞色素 b562 变体：用于检查氧化还原电位演化的库。
DOI：
10.1021/bi0001675
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发表时间：
2000
期刊：
影响因子：
2.9
通讯作者：
McLendon,GL
中科院分区：
文献类型：
--
作者：
Springs,SL;Bass,SE;McLendon,GL
对于细胞色素如何在固定的结构内进化以优化特定生物能量过程的氧化还原潜力，目前还不存在普遍的理解。为此，使用文库方法来研究氧化还原电位的范围和分布，当通过两个位置的突变获得的所有序列空间在固定的结构基序内被检查时。细胞色素b562(E.Coli)的Phe61和Phe65的随机突变，以及随后对该文库的有统计学意义的采样的随后检查，表明通过这两个位置的突变，氧化还原电位可以变化超过100 mV(在轴向His-Met连接的天然蛋白质中，氧化还原电位是已知可及电位的25%)。野生型蛋白质的氧化还原电位出现在观察到的分布的极值，表明Phe61和Phe65最有可能是自然选择的，以不同的方式稳定蛋白质的还原状态。在另一个极端，一组成分保守的突变(F61I，F65Y)导致氧化还原平衡向氧化态移动100 mV。核磁共振分析表明，65位苯丙氨酸突变为酪氨酸所导致的电荷-偶极相互作用可能是原因。
A general understanding of how cytochromes evolve within a fixed structure to optimize redox potential for specific bioenergetic processes does not exist. Toward this end, a library approach is used to investigate the range and distribution of redox potential which occurs when all sequence space available through mutation at two positions is examined within a fixed structural motif. Random mutation of Phe61 and Phe65 of cytochromeb562(E. coli), and subsequent examination of a statistically significant sampling of this library, demonstrates that the redox potential can vary over 100 mV (>25% of the known accessible potential in native proteins with axial His-Met ligation) through mutation at these two positions. The redox potential of the wild-type protein occurs at an extremum of the distribution observed, indicating that Phe61 and Phe65 were most likely naturally selected to differentially stabilize the reduced state of the protein. At the other extremum, a compositionally conservative set of mutations (F61I, F65Y) leads to a 100 mV shift in the redox equilibrium toward the oxidized state. NMR analyses indicate that a charge-dipole interaction which results from mutation of phenylalanine to tyrosine at position 65 may be responsible.