BIOLOGICAL ELECTRON TRANSFER

在我们的总体目标的背景下， 生物电子转移，结构和动力学研究的c-型 细胞色素和其他氧化还原蛋白质将被进行。 我们有 成功地开发了适当的遗传系统， 荚膜红细菌细胞色素c2诱变，并已表征 一些变种人 到目前为止，研究集中在以下方面的影响： 电子转移动力学突变，氧化还原电位，蛋白质 稳定性、蛋白质动力学和蛋白质结构。 此外，本发明还提供了一种方法， 在结构表征方面取得了实质性进展， 高电位铁硫蛋白质的氧化还原特性和 细胞色素 根据我们迄今为止的调查结果，我们提出了一个 全面、综合地研究电子作用机理的计划 转移主要利用细胞色素c2的突变体，并通过研究其 与野生型和突变型光合反应中心的相互作用， 细胞色素c过氧化物酶和细胞色素c1。 虽然主要焦点 将在细胞色素c2，我们将进行平行，但不太广泛， 与其它氧化还原蛋白家族如HIPIP，细胞色素c ′， 植物铁氧还蛋白和多血红素细胞色素。 我们正在将定点突变与一系列 方法，以便在分子术语中定义电子之间的转移， 细胞色素C2和电子供体和受体。 因此，研究 电子转移动力学将与结构研究（NMR）相结合 和X射线晶体学），蛋白质稳定性研究，氧化还原电位 蛋白质动力学（NMR） 预计拟议的研究 将使我们能够解决的作用，静电，空间，距离 氧化还原中心之间，相互作用的氧化还原中心的相对取向， 电子通过其转移的中间介质，以及蛋白质 生物电子传递的动力学。 拟议的研究还将 解决与控制生物氧化还原电位有关的问题， 特定氨基酸对结构域、蛋白质 稳定性，以及控制生物特异性的因素， 识别介导蛋白质-蛋白质相互作用。

In the context of our overall objective of understanding the mechanisms of biological electron transfer, both structural and kinetic studies on c-type cytochromes and other redox proteins will be carried out. We have successfully developed the appropriate genetic system for the site-directed mutagenesis of Rhodobacter capsulatus cytochrome c2 and have characterized a number of mutants. Studies to this point have focused on the effect of mutations on electron transfer kinetics, redox potential, protein stability, protein dynamics and protein structure. In addition, substantial progress has been made on characterization of the structural and redox of properties of the high potential iron sulfur proteins and the cytochromes c'. Based on our findings to date, we are proposing a comprehensive and integrated plan to investigate the mechanism of electron transfer primarily utilizing mutants of cytochrome c2 and by studying their interaction with both wild-type and mutant photosynthetic reaction centers, cytochrome c peroxidase and cytochrome c1. Although the principal focus will be on cytochrome c2, we will carry out parallel but less extensive efforts with other families of redox proteins such as HIPIP, cytochrome c', plant ferredoxin, and multi-heme cytochromes. We are combining the use of site-directed mutagenesis with a range of approaches in order to define in molecular terms electron transfer between cytochrome c2 and electron donors and acceptors. Thus, studies on the kinetics of electron transfer will be combined with structural studies (NMR and x-ray crystallography), studies on protein stability, redox potentials and protein dynamics (NMR). It is anticipated that the proposed studies will permit us to address the role of electrostatics, sterics, distance between redox centers, relative orientation of interacting redox centers, intervening media through which electrons are transferred, and protein dynamics in biological electron transfer. The proposed studies will also address issues related to the control of biological redox potentials, the importance of specific amino acids to structural domains, to protein stability, and the factors controlling biological specificity and recognition that mediate protein-protein interactions.