Structure of reaction intermediates in the bc1 complex

bc1配合物中反应中间体的结构

• 批准号: 7666687
• 负责人: SERGEI A DIKANOV
• 金额: $ 26.11万
• 依托单位: UNIVERSITY OF ILLINOIS AT URBANA-CHAMPAIGN
• 依托单位国家: 美国
• 财政年份: 2002
• 资助国家: 美国
• 起止时间: 2002-03-01 至 2011-07-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7666687
• 关键词: Acquired Immunodeficiency Syndrome; Address; Affect; Aging; Aging-Related Process; Agrochemicals; Apoptosis; Asphyxia; Bacteria; Behavior; Binding; Biochemical; Biological Models; Catalysis; Catalytic Domain; Cell Nucleus; Cessation of life; Characteristics; Chemistry; Complex; Correlation Studies; Cysteine; Cytochrome bc1 Complex; Cytochrome c1; Cytochromes; Cytochromes b; DNA; Data; Defect; Development; Disputes; Drug Delivery Systems; Electron Nuclear Double Resonance; Electron Spin Resonance Spectroscopy; Electron Transport; Electrons; Elements; Energy Metabolism; Engineering; Environment; Enzymes; Equipment and supply inventories; Family; Freezing; Funding; Generations; Heme; Herbicides; Histidine; Housing; Hydrogen Bonding; Hydroquinones; In Vitro; Industrial fungicide; Industry; Investigation; Ions; Iron-Sulfur Proteins; Ischemia; Isotope Labeling; Isotopes; Kinetics; Label; Lead; Ligands; Ligation; Link; Lipids; Magnetism; Malaria; Maps; Mediating; Medical; Membrane; Membrane Proteins; Mitochondria; Mitochondrial DNA; Mitochondrial Myopathies; Modeling; Modification; Molecular; Mutation; Neighborhoods; Nitrogen; Nuclear; Oxidation-Reduction; Oxis; Parasites; Pathology; Pathway interactions; Pesticides; Phase; Photosynthesis; Physiologic pulse; Physiological; Plasmodium; Play; Pneumocystis carinii; Positioning Attribute; Production; Property; Proteins; Protocols documentation; Proton Pump; Protons; Qi; Quinone Reductases; Quinones; Reaction; Reactive Oxygen Species; Reagent; Recovery; Regulation; Relative (related person); Research; Research Personnel; Resolution; Respiratory Chain; Rieske iron-sulfur protein; Role; Side; Site; Solvents; Spectrum Analysis; Stress; Structure; Sulfur; Superoxides; Techniques; Therapeutic Agents; Thermodynamics; Tissues; Toxoplasmosis; Ubiquinone; Work; aqueous; base; comparative; density; design; electronic structure; enzyme substrate; fungus; inhibitor/antagonist; insight; interest; ionization; killings; mutant; oxidation; programs; protein structure; receptor; research study; secondary infection; semiquinone; theories; tool; ubisemiquinone; uptake

DESCRIPTION (provided by applicant): In this proposal we will use high-resolution EPR spectroscopy to explore the catalytic domains of the bc1 complex trapped in states with paramagnetic intermediates bound. The cytochrome bc1 complex family plays an essential role in the energy metabolism of the biosphere. Three catalytic subunits, cyt b, cyt c1 and the Rieske iron sulfur protein (ISP), house the mechanism. Two catalytic sites in cyt b are involved in oxi-dation or reduction of ubiquinone. The integration of the oxidation and reduction reactions with the release or uptake of protons in the aqueous phases, allows the complex to pump protons across the membrane. To understand the mechanism, we need detailed information about the local reaction environment, including protein structure, hydrogen bonding, and distances, to provide the parameters that control rates, and partitioning of electrons to different pathways. Several partial reactions in the bc1 complex involve paramagnetic intermediates. The EPR approach is well suited to dissecting these, because pulsed-EPR techniques can probe interactions between the electron spin of the intermediate and local magnetic nuclei. They thus pro- vide direct information about spatial and electronic structure of the intermediate and the immediate protein and solvent environment. The species at the focus of the proposal are the reduced [2Fe-2S] cluster of the ISP participating in ubihydroquinone (quinol, QH2) oxidation at the Qo-site; and the semiquinone (SQ) involved in the reactions of the quinone-reducing Qi-site. The choreography of catalysis at these sites is largely controlled by the changes in local configuration needed to accommodate the binding requirements of the different quinone forms, and EPR of the SQ provides a direct tool. This work will be pursued in the context of separately funded studies of kinetic and mechanistic aspects, and an extensive inventory of biophysical, biochemical, and molecular engineering protocols allowing us to correlate data for paramagnetic species, and functional and structural changes in mutant strains. The main question to be addressed is that of how the protein environment modifies the spatial and electronic structure of the intermediates to fit the physiological function, a question of much wider interest in reaction mechanism theory. The central role of bc1 complex plays out in many medical scenarios in which defects lead to pathology, among them cellular death through ROS-mediated damage, mitochondrial myopathies, and apoptosis, and in drug targeting.

描述（由申请人提供）：在本提案中，我们将使用高分辨率EPR光谱来探索捕获在顺磁性中间体结合状态下的bc 1复合物的催化域。细胞色素bc 1复合物家族在生物圈的能量代谢中起着重要的作用。三个催化亚基，细胞色素B，c1和Rieske铁硫蛋白（ISP），房子的机制。cyt B中的两个催化位点参与了泛醌的氧化或还原。氧化和还原反应与水相中质子的释放或吸收的整合允许复合物泵送质子穿过膜。为了理解这一机制，我们需要关于局部反应环境的详细信息，包括蛋白质结构、氢键和距离，以提供控制速率的参数，以及电子在不同途径中的分配。bc 1复合物中的几个部分反应涉及顺磁性中间体。EPR方法非常适合于解剖这些，因为脉冲EPR技术可以探测中间磁核和局部磁核的电子自旋之间的相互作用。因此，它们提供了关于中间体的空间和电子结构以及直接蛋白质和溶剂环境的直接信息。该提案的重点是ISP的还原[2Fe-2S]簇参与泛氢醌（quinol，QH 2）在Q-位点的氧化;和参与醌还原Qi-位点反应的半醌（SQ）。在这些网站的催化编排在很大程度上是由本地配置的变化，以适应不同的醌形式的结合要求，和EPR的SQ提供了一个直接的工具。这项工作将在动力学和机械方面的单独资助的研究的背景下进行，以及生物物理，生物化学和分子工程协议的广泛库存，使我们能够关联顺磁性物种的数据，以及突变株的功能和结构变化。要解决的主要问题是，蛋白质环境如何修改的空间和电子结构的中间体，以适应生理功能，一个更广泛的兴趣在反应机理理论的问题。bc 1复合物在许多医学场景中发挥着核心作用，其中缺陷导致病理学，其中包括通过ROS介导的损伤，线粒体肌病和细胞凋亡引起的细胞死亡，以及药物靶向。