Structure around reaction intermediates in bc1 complex

描述（由申请人提供） bc 1复合家族的酶（泛氢醌：细胞色素c（或c2）） 氧化还原酶和与氧化还原酶密切相关的b6 f复合物 光合作用），携带生物圈的能量通量，作为中心 呼吸和光合作用电子传递链的酶。的目的 其母项目是了解这些重要的酶如何发挥作用。 几种线粒体复合体的结构最近提供了新的 对功能的见解，使我们提出了一些新的扩展， 基本的Q循环机制。其中包括一个戏剧性的运动， 两个反应界面之间的铁硫蛋白的外在结构域， 和一个修订的反应机制，其中醌醇被氧化，与 酶-底物复合物性质的具体证据，以及 释放电子和质子的途径。这些结构还 提供了对醌还原位点的更详细的理解， 我们提出了一种新的机制。除了其内在的利益，bc 1 复合物是产生氧自由基的主要场所， 衰老和DNA损伤导致癌症。超氧阴离子的产生 bc 1复合物在机械上与对苯二酚氧化有关，但进化过程中， 尽量减少自杀的副作用我们的研究将提供一个 了解这个重要的医学过程。在这份FIRCA提案中，我们 我将利用这些结构来扩展对当地环境的探索 分子机制，使用高分辨率EPR光谱方法， 利用生物物理学、分子工程学和生物化学 在父母资助下制定的协议。我们将使用2D ESEEM来研究 反应中间体（半醌和还原铁硫）的相互作用 蛋白质）与相邻蛋白质的内源核自旋，以及 合成在特定位置用核标记同位素的泛醌 自旋，以探索这些与顺磁性物质的相互作用， 在催化转换过程中。本研究的综合方面将做 主要在俄罗斯作为NIH资助2 R 01 GM 35438-13的扩展。

DESCRIPTION (provided by applicant) The enzymes of the bc1 complex family (ubihydroquinone:cytochrome c (or c2) oxidoreductases, and the closely related b6f complexes of oxygenic photosynthesis), carry the energy flux of the biosphere, serving as the central enzymes of respiratory and photosynthetic electron transfer chains. The aim of the parent project has been to understand how these important enzymes function. Structures for several mitochondrial complexes have recently provided new insights on function that have led us to suggest some novel extensions of the basic Q-cycle mechanism. These have included a dramatic movement of the extrinsic domain of the iron-sulfur protein between two reaction interfaces, and a revised mechanism for the reaction by which quinol is oxidized, with specific evidence for the nature of the enzyme-substrate complex, and the pathways for release of both electrons and protons. The structures have also provided a more detailed understanding of the quinone reduction site, for which we have suggested a novel mechanism. Apart from its intrinsic interest, the bc1 complex is a major site of production of oxygen radicals, which cause cell aging and DNA damage leading to cancer. Production of superoxide anion by the bc1 complex is mechanistically linked to quinol oxidation, but evolution has minimized this suicidal side-reaction. Our studies will provide an understanding of this medically important process. In this FIRCA proposal, we will make use of the structures in an extended exploration of the local context of molecular mechanism, using high-resolution EPR spectroscopic methods, and taking advantage of the biophysical, molecular engineering and biochemical protocols developed under the parent grant. We will use 2D ESEEM to study the interaction of reaction intermediates (semiquinone and reduced iron-sulfur protein) with endogenous nuclear spins of the neighboring protein, and synthesize ubiquinones isotopically labeled at specific positions with nuclear spins, to explore the interaction of these with paramagnetic species generated during catalytic turnover. Synthetic aspects of this research will be done primarily in Russia as an extension of NIH grant 2 R0l GM 35438-13.