Ultrafast Studies of Electron Transfer in Photosystem II

光系统 II 中电子转移的超快研究

• 批准号: 9727948
• 负责人: Roseanne Sension
• 金额: $ 25.5万
• 依托单位: Regents of the University of Michigan - Ann Arbor
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 1998
• 资助国家: 美国
• 起止时间: 1998-03-01 至 2002-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9727948&HistoricalAwards=false
• 关键词: Ultrafast; Studies; Electron; Transfer; Photosystem

9727948 Sension In this research project state-of-the-art ultrafast spectroscopic techniques will be used to study the primary electron transfer processes in photosystem II. Three specific lines of attack will be pursued in this series of investigations. (1) Ultrafast fluorescence detection will be used to study the excited state population dynamics directly in the D1-D2-Cyt b559 reaction center complex. A streak camera of novel design, which provides greater flexibility, superior signal averaging and sub five picosecond time resolution, will be used. These characteristics are necessary for the study of energy transfer and change separation in PSII. (2) Larger PSII complexes will be prepared in order to study the electron transfer rate in active centers and set to rest any speculation as to whether or not the D1-D2-Cyt b559 complex retains the native reaction center structure and dynamics. The studies will investigate the D1-D2-Cyt b559 complex, the CP47-D1-D2-Cyt b559 complex, and the reaction center core under consistent conditions permitting direct and quantitative comparisons. (3) Finally, the addition of external replacement quinones will be used to study the primary and secondary electron transfer processes in PSII. These measurements will be performed on the D1-D2-Cyt b559 complex and the CP47-D1-D2-Cyt b559 complex. These studies will explore the effect of the presence of a secondary electron acceptor on the population equilibrium distributed over the locally excited fluorescent and charge separated dark states. A rigorous understanding of the primary electron transfer reactions in biological photosynthetic systems is one of the keys to a complete understanding of natural solar energy conversion. The protein complex referred to as photosystem II is responsible for the ability of green plants to utilize light energy to fuel the production of oxygen from water. The PSII protein complex works in conjunction with a second complex, photosystem 1, to form carbohydrates from carbon dioxide. From a chemical point of view, the ability of green plants to produce oxygen and carbohydrates from light, water and carbon dioxide represents an amazing achievement. The overall goal of this investigation is to understand the factors that control the efficiency of photosynthesis in green plants.

9727948 Sension 在这个研究项目中，最先进的超快光谱技术将用于研究光系统 II 中的初级电子转移过程。 这一系列调查将针对三个具体的攻击路线进行。 (1)超快荧光检测将用于直接研究D1-D2-Cyt b559反应中心复合物中的激发态群体动态。 将使用设计新颖的条纹相机，它提供更大的灵活性、卓越的信号平均和低于五皮秒的时间分辨率。 这些特性对于研究 PSII 中的能量传递和变化分离是必要的。 (2) 将制备更大的 PSII 复合物，以研究活性中心的电子转移速率，并消除有关 D1-D2-Cyt b559 复合物是否保留天然反应中心结构和动力学的任何猜测。 这些研究将在允许直接和定量比较的一致条件下研究 D1-D2-Cyt b559 复合物、CP47-D1-D2-Cyt b559 复合物和反应中心核心。 (3)最后，通过添加外部取代醌来研究PSII中的一次和二次电子转移过程。 这些测量将在 D1-D2-Cyt b559 复合物和 CP47-D1-D2-Cyt b559 复合物上进行。 这些研究将探讨二次电子受体的存在对分布在局部激发荧光和电荷分离暗态上的群体平衡的影响。 对生物光合作用系统中初级电子转移反应的严格理解是完整理解自然太阳能转换的关键之一。 被称为光系统 II 的蛋白质复合物负责绿色植物利用光能从水中产生氧气的能力。 PSII 蛋白质复合物与第二个复合物（光系统 1）协同工作，从二氧化碳形成碳水化合物。 从化学角度来看，绿色植物利用光、水和二氧化碳产生氧气和碳水化合物的能力代表了一项惊人的成就。 这项研究的总体目标是了解控制绿色植物光合作用效率的因素。