Structure around reaction intermediates in bc1 complex

bc1复合物中反应中间体周围的结构

• 批准号: 6642199
• 负责人: ANTONY R. CROFTS
• 金额: $ 3.96万
• 依托单位: UNIVERSITY OF ILLINOIS AT URBANA-CHAMPAIGN
• 依托单位国家: 美国
• 财政年份: 2001
• 资助国家: 美国
• 起止时间: 2001-08-01 至 2008-07-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6642199
• 关键词: Commonwealth of Independent States; NADPH cytochrome c2 reductase; electron spin resonance spectroscopy; enzyme complex; hydroquinones; iron sulfur protein; protein structure function; semiquinone; structural biology; superoxides; ubiquinone

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.

描述(申请人提供)Bc1复合体家族的酶(泛氢对苯二酚：细胞色素c(或c2)) 氧化还原酶，以及与之密切相关的含氧b6f络合物 光合作用)，携带生物圈的能量流动，作为中心 呼吸和光合作用电子转移链的酶。的目的是 父项目一直是为了了解这些重要的酶是如何发挥作用的。 几种线粒体复合体的结构最近提供了新的 对功能的洞察，使我们提出了对 基本的Q循环机构。其中包括一场戏剧性的运动 两个反应界面之间的铁-硫蛋白的外在结构域， 并修正了氧化对苯二酚的反应机理， 酶-底物复合体性质的具体证据，以及 释放电子和质子的途径。这些结构还包括 提供了对苯二酚还原部位的更详细的了解 我们提出了一种新的机制。除了它的内在利益，Bc1 复合体是产生氧自由基的主要场所，氧自由基导致细胞 衰老和DNA损伤会导致癌症。微生物法生产超氧阴离子 Bc1复合体在机械上与对苯二酚的氧化有关，但进化有 最小化了这种自杀的副作用。我们的研究将提供一个 了解这一医学上重要的过程。在这份FIRCA提案中，我们 将利用这些结构来扩展对当地背景的探索 分子机制，使用高分辨率的EPR光谱方法，以及 利用生物物理、分子工程和生化 在母公司拨款下制定的协议。我们将使用2D ESEEM来研究 反应中间体(半喹酮和还原铁硫)的相互作用 蛋白质)与邻近蛋白质的内源核自旋，以及 核素标记特定位置的泛醌类化合物的合成 自旋，以探索这些自旋与产生的顺磁物种的相互作用 在催化剂周转过程中。这项研究的综合方面将会完成 主要是在俄罗斯，作为美国国立卫生研究院2号拨款的延伸，GM 35438-13年。