Mechanism and Macromolecular Organization in Photosynthetic Reaction Centers and Membranes

该提案要求继续支持光合反应中心（rc）中电荷分离和重组步骤的生物物理机制以及光合膜的高阶组织。我们工作的一个重要部分是开发新的实验和理论方法，这些方法可以在科学和生物技术的其他领域产生广泛的影响。了解光合系统中能量和电子转移的机制已被证明是这类发展和培养科学家的一个特别肥沃的领域。在本项目中，将在以下具体领域进行与反应中心电荷分离机制相关的研究：(i)利用共振斯塔克光谱确定控制由功能侧单体细菌叶绿素激发引发的替代电子转移途径的基本参数；（ii）将共振斯塔克方法应用于由RC工程创建的其他路径；（iii）测量特殊对三重态衰变的活化能和磁场依赖性，以确定RC突变体中初级电荷分离的能量学；（iv）观察染料分子在功能组分附近的附着，以探测第一个电子转移步骤中电荷运动的动力学；(5)光合膜组分在支撑双层中的组织。通过整合这一系列方法，我们对初始电子转移机制和单向电子转移相关现象的理解可以得到推进，并将其带入复杂生物组装中结构-功能关系的更大背景中。

This proposal requests continued support for biophysical studies of the mechanism of the charge separation and recombination steps in photosynthetic reaction centers (RCs) and the higher-order organization of photosynthetic membranes. An important part of our work involves the development of new experimental and theoretical methods that can have a broad impact in other areas of science and biotechnology. Understanding the mechanisms of energy and electron transfer in photosynthetic systems has proven to be an exceptionally fertile area for such developments and for training scientists. In this project, research will be performed in the following specific areas that relate to the mechanism of charge separation in the reaction center: (i) determination of the fundamental parameters that control alternative electron transfer pathways initiated by excitation of the monomeric bacteriochlorophyll on the functional side using resonance Stark spectroscopy; (ii) application of the resonance Stark method to other pathways created by engineering the RC; (iii) measurements of the activation energy and magnetic field dependence of the decay of the special pair triplet state to determine the energetics of the primary charge separation in RC mutants; (iv) attachment of spectator dye molecules near the functional components to probe the dynamics of charge motion during the first electron transfer step(s); (v) organization of components in the photosynthetic membrane in supported bilayers. By integrating this range of approaches, our understanding of the mechanism of 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.