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Electron and Proton Transfer in Reaction Centers

反应中心的电子和质子转移

基本信息

批准号：
7345410
负责人：
MELVIN Y OKAMURA
金额：
$ 44.48万
依托单位：
UNIVERSITY OF CALIFORNIA, SAN DIEGO
依托单位国家：
美国
项目类别：
财政年份：
1989
资助国家：
美国
起止时间：
1989-04-01 至 2011-01-31
项目状态：
已结题

来源：
https://reporter.nih.gov/project-details/7345410
关键词：
Accounting Address Amino Acids Binding Biological Biological Assay Biological Process Charge Chemicals Complex Condition Coupled Couples Cytochromes Cytochromes c2 Dependence Depth Docking Electron Nuclear Double Resonance Electron Spin Resonance Spectroscopy Electron Transport Electrons Environment Foundations Freezing Future Genetic Genetic Recombination Goals Growth Individual Ionic Strengths Kinetics Lasers Light Measurement Measures Membrane Methods Microscopic Modeling Modification Molecular Molecular Medicine Monitor Mutation Object Attachment Optics Pathway interactions Photosynthetic Reaction Centers Physiologic pulse Positioning Attribute Process Property Protein Dynamics Proteins Proton Pump Protons Pulse taking Quinones Rate Reaction Relaxation Reporter Research Role Site Site-Directed Mutagenesis Solutions Solvents Spectroscopy, Fourier Transform Infrared Spectrum Analysis Structure Surface System Techniques Temperature Testing Ubiquinone Water Work X-Ray Crystallography base benzoquinone cofactor computer studies in vivo infrared spectroscopy mutant photosynthetic bacteria protonation reaction rate rhodoquinone semiquinone structural biology

项目摘要

DESCRIPTION (provided by applicant): The proposed research is a study of electron and proton transfer processes in bacterial reaction centers (RC). These processes are important in many other proteins and form the basis for energy conversion in biological membranes. The overall goal is to provide a description of the molecular basis for this protein in cellular machinery that couples electron transfer to proton pumping across the membrane. The work focuses on two key processes; 1) Proton-coupled electron transfer reactions that result in the reduction of a bound ubiquinone, QB, and 2) Inter-protein electron transfer reaction between cytochrome C2 and RC. The ability to initiate the electron transfer reactions using light pulses allows a detailed understanding of the molecular process involved in these reactions. Site directed mutagenesis will be used to investigate the mechanism of these reactions. The electron transfer rates for the proton-coupled reactions are complex and are believed to involve protein dynamics as well as proton and electron transfer. The molecular basis for the observed electron transfer rate will be examined by site directed mutagenesis to elucidate the factors that control the electron transfer rate. The proton transfer pathway into the QB site is believed to involve surface His residues and a chain of acidic residues and water molecules. The factors important for proton transfer will be investigated by modification of the environment of the residues in the proton transfer pathway and measurement of proton transfer rates using methods that we have developed. The inter-protein electron transfer reaction between cytochrome and RC will be examined to test ideas concerning dynamic docking mechanisms, which involves binding and electron transfer of cytochrome at the RC surface, and electron transfer through solvent water. The structures of the mutants with modified proton and electron transfer rates will be examined by X-ray crystallography, and spectroscopic techniques including electron paramagnetic resonance, electron nuclear double resonance and infrared spectroscopy. The proposed research would help elucidate the molecular basis for electron and proton transfer mechanisms found in many biological systems. The combination of functional assays, genetic information and structural biology provide an understanding of the molecular basis these important biological processes and should help lay the foundations for future advances in molecular medicine.

描述(由申请人提供)：拟议的研究是对细菌反应中心(RC)中的电子和质子转移过程的研究。这些过程在许多其他蛋白质中都很重要，并构成了生物膜中能量转换的基础。总体目标是描述这种蛋白质在细胞机制中的分子基础，这种机制将电子传递耦合到跨膜的质子泵。工作集中在两个关键过程：1)质子耦合的电子转移反应，导致结合的泛醌QB的还原；2)细胞色素C2和RC之间的蛋白质间电子转移反应。使用光脉冲启动电子转移反应的能力使我们能够详细了解这些反应所涉及的分子过程。定点突变将被用来研究这些反应的机制。质子偶联反应的电子转移速率是复杂的，被认为涉及蛋白质动力学以及质子和电子转移。观察到的电子转移速率的分子基础将通过定点突变来研究，以阐明控制电子转移速率的因素。进入QB位点的质子转移途径被认为涉及表面组氨酸残基和一系列酸性残基和水分子。将通过改变质子转移途径中残基的环境和使用我们开发的方法测量质子转移速率来研究对质子转移重要的因素。将研究细胞色素与RC之间的蛋白质间电子转移反应，以测试有关动态对接机制的想法，该机制涉及细胞色素在RC表面的结合和电子转移，以及通过溶剂水的电子转移。用X射线结晶学和光谱技术，包括电子顺磁共振、电子核双共振和红外光谱技术，将研究具有改进的质子和电子转移速率的突变体的结构。这项拟议的研究将有助于阐明在许多生物系统中发现的电子和质子转移机制的分子基础。功能分析、遗传信息和结构生物学的结合提供了对这些重要生物学过程的分子基础的理解，并应有助于为未来分子医学的发展奠定基础。