Mechanism and Macromolecular Organization in Photosynthetic Reaction Centers

9807559 Boxer本项目的目的是研究光合细菌反应中心（RC）中电荷分离和重组步骤的机制。 解决这些问题的具体方法包括：（i）利用局部激发态和电荷转移态之间的耦合的分析处理，对影响特殊对（P）的突变体的吸收和Stark光谱进行定量分析，以获得关于1 P的电子性质的信息;（ii）应用本实验室发展的高阶斯塔克方法研究电子转移的机制和单向电子转移的起源，（iii）产生不结合类胡萝卜素的RC，并在这些不含类胡萝卜素的RC中测量特殊对的磷光光谱和3 P衰变的活化能，以确定RC突变体中初级电荷分离的能量学;以及（v）利用横向电场诱导的浓度分布和原子力显微镜，在支撑的脂质双层中使用RC作为组装和成像光合膜组分的组织的成核位点。光合作用是将太阳能转化为有用燃料的过程。 因此，所涉及的过程是自然界中最重要的过程之一。 此外，所涉及的基本步骤，能量转移，电子转移和质子转移，是化学和生物学中最普遍的过程。 光合反应中心精心制作，以优化这些过程中的每一个，这项研究旨在了解这是如何工作的。 通过研究一个由光启动功能的系统，可以在非常明确的条件下研究其机制，这在复杂的生物系统中是很少可能的。这项研究所提出的特定技术问题的答案也影响了蛋白质中长距离电子转移和静电学等更广泛的问题，并在材料科学和复杂系统中自组装的分析中产生了进一步的影响和应用。

9807559BoxerThe goal of this project is to study the mechanism of the charge separation and recombination steps in reaction centers (RCs) from photosynthetic bacteria. Specific approaches to these problems include: (i) quantitative analysis of the absorption and Stark spectra of mutants that affect the special pair (P) using an analytical treatment of the coupling between locally-excited and charge transfer states to obtain information on the electronic properties of 1P; (ii) application of the higher-order Stark method developed in this laboratory to study the mechanism of electron transfer and the origins of unidirectional electron transfer, (iii) creation of an RC that does not bind carotenoid and measurements in these carotenoid-free RCs of phosphorescence spectra of the special pair and the activation energy of 3P decay to determine the energetics of the primary charge separation in RC mutants; (iv) estimation of differences in electronic coupling on the L-vs M-side using ultrafast singlet energy transfer in RC mutants; and (v) use of RCs in supported lipid bilayers as a nucleation site for assembling and imaging the organization of photosynthetic membrane components using lateral electric field-induced concentration profiles and atomic force microscopy.Photosynthesis is the process by which solar energy is converted into useful fuel. As such, the processes involved are among the most important in nature. Furthermore, the elementary steps involved, energy transfer, electron transfer and proton transfer, are among the most universal processes in chemistry and biology. The photosynthetic reaction center is beautifully crafted to optimize each of these processes and this research aims to understand how this works. By working with a system whose function is initiated by light, it is possible to study the mechanism under very well defined conditions, something that is rarely possible with complex biological systems. The answers to the particular technical questions posed by this research also impact wider issues of long distance electron transfer and electrostatics in proteins, with further implications and applications in materials science and the analysis of self-assembly in complex systems.