Electron Transfer within Protein Complexes

描述(申请人提供)：这个研究蛋白质间电子转移(ET)的项目旨在了解控制蛋白质ET伙伴之间的界面识别和反应性对接的基本结构、动态和能量特征；*对接伙伴之间ET的实际过程。我们研究三个蛋白质系统，每个系统都提供了解决这些问题的不同机会：混合金属[锌，Fe3+L]血红蛋白杂化使我们能够通过结晶学定义的、非共价耦合的界面，在‘预对接’的蛋白质-蛋白质复合体中研究ET；细胞色素c过氧化物酶(CCP)与细胞色素c(CC)的复合体以CCP为典型蛋白质，具有两个ET活性和可交流的氧化还原中心，以及两个不同的表面域用于结合其ET伙伴；生理上重要的细胞色素b5与肌红蛋白(Mb)和血红蛋白(Hb)的ET复合体代表了一种新的动态对接模式，其中有许多对接构型，但最具反应性的不是最有利于结合的。在上述目标下包含的一系列个人目标中，我们仅注意到对我们未来一段时间的努力至关重要的几个目标：(I)表征蛋白质波动控制蛋白质间ET的方式，以及它们可以通过与外部介质的耦合来调节的程度。(Ii)建立两个CCP位点之间的ET在CCP和CC之间的ET动力学中的作用。(3)实施一项计划，通过实验确定偶极作用力而不是单极相互作用控制蛋白质-蛋白质对接的程度。为了实现我们的目标，我们将应用和扩展广泛的动力学、热力学、光谱和理论方法。新的方法和策略包括对溶胶-凝胶中蛋白质-蛋白质ET的广泛研究。我们解决的问题和我们开发的策略的应用远远超出了我们研究的ET反应。

DESCRIPTION (provided by applicant): This program in the study of inter-protein electron transfer (ET) aims to understand the fundamental structural, dynamic and energetic features that control, * lnterfacial recognition and reactive docking between protein ET partners; *The actual process of ET between docked partners.We study three protein systems, each offering distinct opportunities to address these issues: mixed-metal [Zn, Fe3+L] hemoglobin hybrids allow us to study ET within a 'predocked' protein-protein complex, across a crystallographically defined, non-covalently coupled interface; the complex of cytochrome c peroxidase (CcP) with cytochrome c (Cc) involves CcP as the archetypical protein which has two ET-active and communicating redox centers, as well as two distinct surface domains for binding its ET partner; the physiologically important ET complexes of cytochrome b5 with myoglobin (Mb) and hemoglobin (Hb) represent a new 'dynamic docking' paradigm in which there are many docked configurations, but the most reactive are not the most favorable for binding. Among a broad array of individual goals subsumed under the above aims, we merely note several that are central to our efforts in the coming period: (i) Characterize the ways in which protein fluctuations control interprotein ET, and the degree to which they can be modulated by coupling to the external medium .(ii) Establish the role of ET between the two CcP sites in the kinetics of ET between CcP and Cc. (iii) Implement a plan to experimentally establish the degree to which dipole forces, rather than monopole interactions, control protein-protein docking. To realize our aims, we shall apply and extend a broad range of kinetic, thermodynamic, spectroscopic, and theoretical methods. New approaches and strategies include, among others, extensive studies of protein-protein ET in sol-gels. The issues we address and the strategies we develop have applications extending far beyond the ET reaction we study.