Electron Transfer within Protein Complexes

描述（申请者提供）：该项目是蛋白质间电子转移（ET）的研究方向，旨在了解蛋白质间电子转移伙伴之间控制、界面识别和反应对接的基本结构、动力学和能量特征；*对接伙伴之间ET的实际过程。我们研究了三种蛋白质系统，每种系统都为解决这些问题提供了不同的机会：混合金属[Zn， Fe3+L]血红蛋白杂交体使我们能够在“预先对接”的蛋白质-蛋白质复合物中研究ET，跨越晶体学定义的非共价偶联界面；细胞色素c过氧化物酶（CcP）与细胞色素c （Cc）的复合物涉及CcP作为典型蛋白，具有两个ET活性和交流氧化还原中心，以及两个不同的表面结构域用于结合其ET伴侣；细胞色素b5与肌红蛋白（Mb）和血红蛋白（Hb）在生理上具有重要意义的ET复合物代表了一种新的“动态对接”模式，其中有许多对接构型，但最活跃的不是最有利于结合的。在上述目标下包含的一系列广泛的个人目标中，我们只注意到对我们今后一段时期的工作至关重要的几个目标：(i)描述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耦合来调节的程度。（ii）确定两个CcP位点之间的ET在CcP和Cc之间ET动力学中的作用。（iii）实施一项计划，通过实验确定偶极子力而不是单极子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在溶胶-凝胶中广泛研究蛋白质-蛋白质ET。我们解决的问题和我们开发的策略的应用范围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.