VIBRATIONAL STUDIES OF ENERGY TRANSDUCING PROTEINS

能量转换蛋白的振动研究

• 批准号: 6018723
• 负责人: DAVID F. BOCIAN
• 金额: $ 13.74万
• 依托单位: UNIVERSITY OF CALIFORNIA RIVERSIDE
• 依托单位国家: 美国
• 财政年份: 1988
• 资助国家: 美国
• 起止时间: 1988-07-01 至 2000-07-02
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6018723
• 关键词: Raman spectrometry; Rhodospirillales; bacterial pigment; biophysics; chemical bond resonance; chemical kinetics; chemical structure function; chlorophyll; cofactor; conformation; electric field; electron density; electron transport; electronic spectra; mutant; photochemistry; photosynthetic bacteria; photosynthetic reaction centers; reducing agents

The specific aims of the proposed research are to characterize the structural, vibronic, and electronic properties of the photophysically active bacteriochlorophyll (BChl) and bacteriopheophytin (BPh) cofactors in bacterial photosynthetic reaction centers (RCs). Bacterial RCs were chosen for study because of this class of proteins represents a prototypical model system for investigating the factors which mediate charge separation across a biological membrane. The utility of bacterial RCs for examining this process is due to the fact that (1) high-resolution X-ray crystallographic data are available for RCs from several species and (2) genetic engineering techniques are well developed for certain of these species. These two criteria are not satisfied for any mammalian membrane-bound proteins involved in primary charge-separation and energy-transduction processes. The principal investigative tool for the studies is resonance Raman (RR) spectroscopy. The first major objective is to characterize the properties of the BChl/BPh cofactors in genetically modified RCs which exhibit novel electron-transfer properties. These studies will focus on a series of mutants of Rb, capsulatus wherein replacements have been made in amino acid residues which are in close proximity to the accessory BChl and BPh cofactors on the electron-transfer active L branch of the protein. The genetically modified RCs will include mutants in which electron transfer has been first documented to proceed down the normally inactive M branch of the protein. In all cases the RR studies will be conducted on RCs hose detailed electron-transfer kinetics have been elucidated via time-resolved optical experiments. The second major objective is to conduct RR studies on RCs aimed at determining the nature of the low-frequency vibrational modes of athe BChl/BPh cofactors which are strongly coupled to the lowest- energy optical transition(s). The principal target of these studies is the primary electron donor. The characterization of the low-frequency modes will proceed via acquisition and analysis of RR data from RCs labeled with 15N, 26Mg, and 15N/26Mg. The long-term objective of all the studies is to determine how the physical properties of the cofactors (structure, electron-density distribution, electron-phonon coupling) govern and/or reflect their functional characteristics (electron transfer and charge separation across the biological membrane).

拟议研究的具体目的是描述 光物理的结构、振动和电学性质 细菌叶绿素(BCHL)和细菌叶绿素(BPH)的辅因子 细菌光合作用反应中心(RCS)。选择细菌RCS 因为这类蛋白质代表了一个原型模型 用于研究影响电荷分离的因素的系统 一种生物膜。细菌RCS在检测这方面的应用 过程是由于以下事实：(1)高分辨率X射线结晶学 有几个物种和(2)基因工程的RCS数据可用 对于这些物种中的某些物种，技术已经发展得很好了。这两个 任何哺乳动物膜结合蛋白的标准都不满足 参与初级电荷分离和能量转换过程。 研究的主要研究工具是共振拉曼光谱(RR) 光谱学。第一个主要目标是表征这些特性 转基因RCS中BCHL/BPH辅助因子的研究 电子转移性质。这些研究将集中在一系列 囊状Rb的突变体，其中氨基酸已被取代 与副BCHL和BPH密切相关的残留物 辅因子对电子传递活性较高的L支链蛋白。这个 转基因RCS将包括电子转移的突变体 最早被证明沿着通常不活跃的M支行 蛋白质。在所有情况下，RR研究都将在RCS软管上进行 通过时间分辨阐明了详细的电子转移动力学。 光学实验。第二个主要目标是进行RR研究 关于旨在确定低频振动性质的RCS BCHL/BPH共因子的模式强耦合到最低- 能量光学跃迁(S)。这些研究的主要目标是 主要的电子给体。低频模式的表征 将通过从RCS获取和分析RR数据来进行，RCS标记为 15N、26 mg和15N/26 mg。所有研究的长远目标是 确定辅因子的物理性质(结构， 电子密度分布、电子-声子耦合)控制和/或 反映其功能特征(电子转移和电荷 生物膜上的分离)。