Structure of reaction intermediates in the bc1 complex

bc1配合物中反应中间体的结构

基本信息

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
项目类别：
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

项目摘要

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）：在此提案中，我们将使用高分辨率EPR光谱探索捕获在具有顺向磁中间体结合的状态的BC1复合物的催化域。细胞色素BC1复合体系列在生物圈的能量代谢中起着至关重要的作用。三个催化亚基Cyt B，Cyt C1和Rieske铁硫蛋白（ISP），容纳机制。 Cyt B中的两个催化位点参与氧化或泛氨基酮的还原。氧化和还原反应与水相中质子的释放或摄取的整合，使复合物可以在整个膜上泵送质子。为了了解该机制，我们需要有关局部反应环境（包括蛋白质结构，氢键和距离）的详细信息，以提供控制速率的参数以及将电子划分为不同途径的参数。 BC1复合物中的几种部分反应涉及顺磁中间体。 EPR方法非常适合剖析这些方法，因为脉冲-EPR技术可以探测中间和局部磁核的电子自旋之间的相互作用。因此，他们提供了有关中间体以及直接蛋白质和溶剂环境的空间和电子结构的直接信息。该提案重点的物种是参与QO地点的Ubihydroquinone（Quinol，QH2）氧化的ISP的[2FE-2S]簇。以及参与奎因酮还原Qi位点反应的半喹酮（SQ）。这些站点上催化的编排在很大程度上受到适应不同喹酮形式的绑定要求所需的局部配置的变化，而SQ的EPR提供了直接的工具。这项工作将在分别资助的动力学和机械方面的研究中进行，以及对生物物理，生化和分子工程方案的广泛清单，使我们能够将数据磁性物种以及突变株中的功能和结构变化相关联。要解决的主要问题是蛋白质环境如何修饰中间体的空间和电子结构以适合生理功能，这是对反应机理理论的更广泛兴趣的问题。 BC1复合体的核心作用在许多医学情况下扮演了病理学，其中包括通过ROS介导的损伤，线粒体肌病和细胞凋亡以及药物靶向的细胞死亡。