Mechanism and Macromolecular Organization in Photosynthetic Reaction Centers

光合反应中心的机理和大分子组织

• 批准号: 9506178
• 负责人: Steven Boxer
• 金额: $ 35.96万
• 依托单位: Stanford University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 1995
• 资助国家: 美国
• 起止时间: 1995-08-01 至 1999-01-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9506178&HistoricalAwards=false
• 关键词: Mechanism; Macromolecular; Organization; Photosynthetic; Reaction

9506178 Boxer This research grant funds continued support for biophysical studies of the mechanism of charge separation and recombination processes in reaction centers (RCs) from photosynthetic bacteria. The specific approaches to these problems include: (i) the nature of the excited state of the special pair primary electron donor, 1P, which initiates charge separation probed by resonance Raman and higher order Stark spectroscopies; (ii) distinguishing one step and two step electron transfer by measurements on RCs in which components are modified or removed by genetic engineering; (iii) electric field modulation of the spontaneous fluorescence from 1P to determine whether the field affects the primary charge separation step and the direction of the electric dipole moment whose formation competes with 1P decay; (iv) studies of the interaction between the bacteriochlorophyll molecules comprising P and the protein environment by converting residues which make functionally specific interactions with P into glycine, creating cavities which can bind exogenous organic molecules to modulate photosynthetic function; and (v) the origin of unidirectional electron transfer probed by site specific mutagenesis based both on measurements of dielectric asymmetry and an evolutionary analysis. %%% The initial electron transfer events in photosynthetic RCs are the key energy transduction and storage mechanisms essential for all aspects of life on earth. Studies of this system, both at the detailed molecular level and from a more global perspective, can offer approaches for improving natural photosynthesis and modeling artificial photosynthesis. The photosynthetic apparatus is largely a membrane protein complex whose structure elucidation over the past 10 years has provided, for the first time, information on the folding and organization of membrane proteins. It is likely that within the next 5 years, the overall organization of the photosynthetic membrane will be fully characteriz ed, a unique and major achievement in biology. Electron transfer in photosynthetic proteins provides a paradigm for understanding the factors that control the rapid movement of electrons on the nanometer scale, and thus have greatly influenced thinking and prospects for molecular scale electronic devices. This research focuses on understanding the mechanism of the earliest, light driven electron transfer reactions, the unique excited state properties that lead to efficient charge separation, and the interactions between the chlorophyll type molecules and their protein environment which modulate the properties of these chromophores and uniquely determine the direction of electron flow. ***

9506178拳击手这项研究拨款继续支持光合细菌反应中心(RC)电荷分离和重组过程的生物物理研究。解决这些问题的具体方法包括：(I)特殊对初级电子给体1P的激发态的性质，它启动了用共振拉曼光谱和高阶Stark光谱探测的电荷分离；(Ii)通过RCS上的测量区分一步和两步电子转移，其中的成分被基因工程修饰或去除；(Iii)电场对1P的自发荧光进行调制，以确定电场是否影响初级电荷分离步骤和形成与1P衰变竞争的电偶极矩的方向；(Iv)通过将与磷进行功能特异性相互作用的残基转化为甘氨酸，产生能与外源有机分子结合以调节光合作用的空腔，研究含有磷的细菌-叶绿素分子与蛋白质环境之间的相互作用；以及(V)基于介电不对称测量和进化分析，通过定点突变来探索单向电子转移的起源。光合作用RCS中的初始电子传递事件是地球上生命各方面所必需的关键的能量传递和储存机制。对这一系统的研究，无论是在详细的分子水平上，还是从更全球的角度，都可以为改善自然光合作用和模拟人工光合作用提供途径。光合作用装置在很大程度上是一个膜蛋白复合体，其结构的阐明在过去10年中首次提供了膜蛋白折叠和组织的信息。很可能在接下来的5年内，光合膜的整体结构将得到充分的表征，这是生物学上一项独特的重大成就。光合作用蛋白质中的电子转移为理解在纳米尺度上控制电子快速运动的因素提供了一个范例，从而极大地影响了分子尺度电子器件的思考和前景。这项研究的重点是了解最早的光驱动电子转移反应的机制，导致有效电荷分离的独特激发态性质，以及叶绿素型分子与其蛋白质环境之间的相互作用，这些相互作用调节这些生色团的性质，并唯一地决定电子流动的方向。***