Bacterial Reaction Centers With New Photochemical Properties

在所有的光合系统中，主要的能量转换事件是光诱导色素蛋白复合物中电荷分离态的产生。 虽然生物体之间的具体途径各不相同，但一般模式是非常保守的，对这些过程的理解是目前模拟光合作用过程的人工系统设计的基础。 从球形红细菌作为光系统II的模型的反应中心的有用性说明了以前的工作，其中氧化还原活性锰辅因子绑定到反应中心的位置类似于光系统II的锰簇。 该项目的第一个具体目标是表征反应中心中结合Mn和其他新金属辅因子的性质。 各种各样的光谱技术将被用来确定的结构特性，金属辅因子的电子结构，和电子转移特性，为理解金属结合的特异性，控制金属的活性的因素，以及如何涉及金属辅因子的反应是由蛋白质相互作用控制的基础。 第二个具体目标是设计具有多核Mn簇的蛋白质。 集群的组装将接近三个独立的途径：一个半合成的方法，其中各种锰化合物将绑定到蛋白质，应用程序的自组装原则的Mn集群的光系统II，并引入新的配体的结合双核和四核Mn集群。 新的锰辅因子的掺入应阐明金属簇与蛋白质结合的分子要求。 关于电子转移蛋白质与新的金属辅因子的洞察力应该提供的基础设计的蛋白质能够光驱动的金属为基础的催化。 研究目标的实现将对理解光合作用和太阳能装置的发展产生影响。 该项目为本科生和研究生提供多学科培训，并通过合作进行国际交流。 许多项目概念，特别是光合作用在能源利用中的作用和用于研究反应中心的光谱技术的基本原理，将被纳入为不同背景的学生开发的课程，以及由主要研究者撰写的本科教育教科书。

In all photosynthetic systems, the primary energy transduction event is the light-induced generation of a charge-separated state in a pigment-protein complex. Although the specific pathways vary among organisms, the general pattern is remarkably conserved, and an understanding of these processes serves as the basis for current designs of artificial systems that mimic the photosynthetic process. The usefulness of the reaction center from Rhodobacter sphaeroides as a model for photosystem II is illustrated by previous work in which a redox-active Mn cofactor was bound to the reaction center at a location analogous to that of the Mn cluster of photosystem II. The first specific aim of the project is to characterize the properties of the bound Mn and other new metal cofactors in the reaction center. A wide variety of spectroscopic techniques will be utilized to determine the structural properties, the electronic structure of the metal cofactor, and the electron transfer properties, providing the basis for understanding the specificity for metal binding, the factors that control the activity of the metal, and how reactions involving metal cofactors are controlled by protein interactions. The second specific aim is to design proteins with multinuclear Mn clusters. The assembly of clusters will be approached by three independent avenues: a semi-synthetic method in which a variety of Mn compounds will be bound to the protein, the application of the self-assembly principles of the Mn cluster of photosystem II, and the introduction of new ligands for the binding of binuclear and tetranuclear Mn clusters. The incorporation of new Mn cofactors should shed light into the molecular requirements for the binding of metal clusters to proteins. The insight gained regarding electron transfer proteins with new metal cofactors should provide the foundation for the design of proteins capable of light-driven metal-based catalysis. Achievement of the research goals should have an impact on understanding photosynthesis and the development of solar-energy devices. Broader impactsThe project provides multidisciplinary training for undergraduate and graduate students and international exposure through collaborations. Many project concepts, notably the role of photosynthesis in energy utilization and the fundamentals of spectroscopic techniques used to study reaction centers, will be included in the development of courses for students of different backgrounds, as well as a textbook for undergraduate education authored by the principal investigator.