Mechanism and Macromolecular Organization in Photosynthetic Reaction Centers

本研究的目的是了解光合反应中心（RC）中电荷分离和重组的机制以及光合膜的高级组织。 为了更好地理解电子转移机理，本文介绍了几个方面：（i）新发展的用于测量Stark效应的仪器在红外光谱中的应用和分析氧化特殊电子对的价带间Stark效应的理论;（ii）用新发展的实验方法--共振Stark光谱法确定控制电子转移途径的参数;（iv）测量电场对光系统II RC中电荷分离物种群体的影响，特别是类胡萝卜素阳离子的作用;和（v）RC菌株的开发和应用，其中所有天然半胱氨酸残基被缺失，新的半胱氨酸被插入作为不同类型标记的位点特异性靶。 为了了解光合膜的组织和组装几个领域进行了描述：（一）表征的横向流动性和组装的天线蛋白复合物在支持膜;和（二）成像的组件支持脂质双层的光合膜的原子力显微镜和一种新型的二次离子质谱与高横向分辨率。 这项研究使用支持膜中的光合蛋白作为推进成像和结构方法的工具，并确定这种重要的膜相关组装的远程组织。可以推进对初始电子转移机制和单向电子转移相关现象的基本理解，并将其带入更大的结构背景中，在复杂的生物组装中的功能关系。 光合作用领域的研究解决了蛋白质中有组织的环境调节结合辅基和具有非凡功能后果的特定氨基酸官能团的性质的机制的一般问题。 这项工作的一个重要组成部分是开发新的实验和理论方法，这些方法可以在其他科学和技术领域产生广泛的影响。 几乎每一个光谱，结构和理论方法已被应用到某些方面的RC和光合膜功能。 在许多情况下，这是新的物理方法应用于生物学问题的第一个例子，通常导致物理和理论方法的显着改进，这些概念和方法现在被用于许多其他领域。 这一一般研究领域也一直是本科生、研究生和博士后研究员的巨大培训来源，经常充当物理科学和生物学之间的桥梁。 从广义上看，光合作用研究的概念和结果影响了太阳能研究和新兴的分子电子学领域。

AbstractMCB 0416623The objective of this research is to understand the mechanisms of charge separation and recombination in photosynthetic reaction centers (RCs) and the higher-order organization of photosynthetic membranes. Towards understanding electron transfer mechanism, several areas are described: (i) application of newly developed instrumentation for measuring Stark effects in the IR and theory for analyzing intervalence band Stark effects associated with the oxidized special pair; (ii) determination of the parameters that control alternative electron transfer pathways using a newly-developed experimental method, resonance Stark spectroscopy; (iii) application of the resonance Stark method to other pathways created by engineering the RC; (iv) measurement of electric field effects on the populations of charge-separated species in photosystem II RCs, in particular the role of carotenoid cations; and (v) development and application of RC strains in which all native cysteine residues are deleted and new cysteines are inserted as site-specific targets for different types of labels. Towards understanding photosynthetic membrane organization and assembly several areas are described: (i) characterization of the lateral mobility and assembly of antenna protein complexes in supported membranes; and (ii) imaging of components of the photosynthetic membrane in supported lipid bilayers by atomic force microscopy and a novel type of secondary ion mass spectrometry with high lateral resolution. This research uses photosynthetic proteins in supported membranes both as a tool to advance imaging and structural methods and to determine the long-range organization of this important membrane-associated assembly.By integrating this range of approaches, the basic understanding of the mechanism of the initial electron transfer and the related phenomenon of unidirectional electron transfer can be advanced and brought into the larger context of structure-function relationships in complex biological assemblies. Research in the photosynthesis area addresses the general problem of the mechanisms by which the organized environment in proteins modulates the properties of bound prosthetic groups and particular amino acid functional groups with extraordinary functional consequences. An important part of this work involves the development of new experimental and theoretical methods that can have a broad impact in other areas of science and technology. Nearly every spectroscopic, structural, and theoretical method has been applied to some aspect of RC and photosynthetic membrane function. In many cases this was the first example of new physical approaches applied to a biological problem, often leading to significant improvements in the physical and theoretical methods, and these concepts and methods are now used in many other fields. This general area of research has also been a tremendous source of training for undergraduates, graduate students and postdoctoral fellows, often serving as a bridge between the physical sciences and biology. Viewed in broadest terms, concepts and results from photosynthesis research have impacted solar energy research and the emerging area of molecular electronics.