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在这项研究项目中，将使用最先进的超快光谱技术来研究光系统II中的初级电子转移过程。在这一系列的研究中，将采取三条具体的攻击线。(1)超快荧光检测将直接用于研究D1-D2-Cytb559反应中心络合物中的激发态布居动力学。将使用设计新颖的条纹相机，提供更大的灵活性、卓越的信号平均和低于5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络合物，以研究活性中心的电子转移速率，并平息关于D1-D2-Cytb559络合物是否保留自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复合体、CP47-D1-D2-Cyt b559复合体和反应中心核心。(3)最后，我们将利用外加取代苯二酚来研究PSII中的一次和二次电子转移过程。这些测量将在D1-D2-Cyt b559复合体和CP47-D1-D2-Cyt b559复合体上进行。这些研究将探索次级电子受体的存在对分布在局部激发的荧光和电荷分离暗态上的布居平衡的影响。对生物光合作用系统中的初级电子转移反应的严格理解是全面理解自然太阳能转换的关键之一。被称为光系统II的蛋白质复合体负责绿色植物利用光能从水中生产氧气的能力。PSII蛋白复合体与第二个复合体--光系统1一起工作，从二氧化碳中形成碳水化合物。从化学角度来看，绿色植物从光、水和二氧化碳中产生氧气和碳水化合物的能力是一项令人惊叹的成就。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。