Flavocytochrome b(2): An ideal model system for studying protein-mediated electron transfer
Flavocytochrome b(2): An ideal model system for studying protein-mediated electron transfer
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DOI：
10.1042/bst0240073
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发表时间：
1996-02-01
影响因子：
3.9
通讯作者：
Daff, S
中科院分区：
文献类型：
--
作者：
Chapman, SK;Reid, GA;Daff, S
最近的大部分密集的科学努力，以提供一个了解蛋白质中的电子转移集中在蛋白质内的电子转移和供体（D）和受体（A）的氧化还原中心之间的途径。这些中心通常固定在蛋白质基质中，如光合反应中心的情况[1]，或者涉及将人工氧化还原中心附着在蛋白质表面上与天然中心固定距离处，例如在“双烯化”蛋白质中[Z]。这类研究通常简化为分析电子是否直接通过空间从D到A（即将中间的蛋白质介质视为均匀的“有机玻璃”），或者它是否通过涉及特定共价键，氢键等的独特o-隧道路径行进。(ie将蛋白质培养基作为异质处理）。除了D和A之间的距离之外，电子转移的速率还受到反应驱动力AGO和重组能i的影响[ 13]。除了蛋白质内的电子转移，其中氧化还原中心是固定在一个蛋白质内，也有强烈的兴趣，在蛋白质之间的双分子反应，导致蛋白质间的电子转移。在这里，必须考虑两种蛋白质之间相互作用的动力学。这两种蛋白质是否形成一个确定的复合物，在氧化还原中心之间具有特定的电子转移路径？蛋白质上是否有许多可能的位点，在这些位点上结合后发生电子转移？一个有趣的例子是细胞色素c和细胞色素c过氧化物酶之间的复合物，现在有晶体结构[3]。基于这种结构，已经提出了连接两个血红素基团的O-隧道通道[3]。然而，细胞色素c-细胞色素c过氧化物酶相互作用动力学的NMR研究表明，溶液中的复合物具有高度移动的，可能不具有具有特定电子转移途径的离散结构[4]。
Most of the recent intense scientific effort towards providing an understanding of electron transfer in proteins has focused on intraprotein electron transfer and on the pathway between the donor (D) and acceptor (A) redox centres. These centres are usually fixed within the protein matrix as in the case of the photosynthetic reaction centre [l], or involve attaching an artificial redox centre onto the surface of a protein at a fixed distance from the natural centre, eg in ‘ruthenated’proteins [Z]. Such studies usually reduce to an analysis of whether the electron travels from D to A directly through space (ie treating the intervening protein medium as homogeneous like an ‘organic glass’), or whether it travels through a distinct o-tunnelling pathway involving specific covalent bonds, hydrogen bonds, etc.(ie, treating the protein medium as heterogeneous). As well as the distance between D and A, the rate of electron transfer is also influenced by the driving force of the reaction, AGO, and the reorganization energy, i [ 13. In addition to intraprotein electron transfer, in which the redox centres are fixed within one protein, there is also intense interest in bimolecular reactions between proteins which result in interprotein electron transfer. Here, one must consider the dynamics of the interactions between the two proteins involved. Do the two proteins form one defined complex with a specific electron transfer path between redox centres? Are there a number of possible sites on the proteins where binding followed by electron transfer can occur? An interesting example is the complex between cytochrome c and cytochrome c peroxidase for which there is now a crystal structure [3]. Based on this structure a o-tunnelling pathway linking the two haem groups has been proposed [3]. However an NMR study of the dynamics of the cytochrome c-cytochrome c peroxidase interaction indicates that the complex in solution is highly mobile and probably does not have a discrete architecture with one specific electron transfer pathway [4].