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: 9418390
• 负责人: Roseanne Sension
• 金额: $ 27万
• 依托单位: Regents of the University of Michigan - Ann Arbor
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 1995
• 资助国家: 美国
• 起止时间: 1995-01-01 至 1998-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9418390&HistoricalAwards=false
• 关键词: Ultrafast; Studies; Electron; Transfer; Photosystem

9418390 Sension A proper understanding of the primary energy transfer and electron transfer processes in photosynthetic systems is one of the keys to a complete understanding of natural solar energy conversion. In this research project state-of-the-art ultrafast spectroscopic techniques will be uqed to study the primary electron transfer processes in photosystem II. Several types of experiments will be performed to try to elucidate the time-scale and mechanism for primary charge separation in PSII. These include the following: The ultrafast kinetics will be measured using various reaction center preparations to determine whether the method of preparation can affect either the energy relaxation kinetics or the rate of primary charge separation. 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. Transient absorption measurements will be made with ultrashort (50 fs) pulses to explore the possible involvement of coherent protein motion in the initial dynamics of PSII. Resonance Raman measurements will be attempted to probe the production of the initial charge separated state directly, overcoming the limitation of highly overlapping electronic absorption features. Combining the slight differences in the electronic spectra with the selectivity introduced by resonance enhancement and the differences in the vibrational spectra of the charged and neutral pigments, it should be possible to detect the charge separated state with much less ambiguity. %%% 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 (PSII) is responsible for the ability of green plants to utilize light energy to fuel the pr oduction of oxygen from water. The PSII protein complex works in conjunction with a second complex, photosystem I (PSI), to form carbohydrates from carbon dioxide. In this research project, state-of-the-art laser technology will be used to study the light initiated electron transfer reactions of photosystem II (PSII). The overall goal of this investigation is to obtain a detailed understanding of the factors that control the efficiency and robustness of photosynthesis in green plants. ***

正确理解光合系统的一次能量传递和电子传递过程是全面理解自然太阳能转换的关键之一。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。将进行几种类型的实验，以试图阐明PSII中初级电荷分离的时间尺度和机制。这些包括：超快动力学将使用各种反应中心制剂来测量，以确定制备方法是否会影响能量松弛动力学或一次电荷分离速率。制备更大的PSII配合物是为了研究活性中心的电子转移速率，并使D1-D2-Cyt b559配合物是否保留了天然反应中心结构和动力学的任何猜测停止。瞬态吸收测量将用超短（50 fs）脉冲进行，以探索相干蛋白运动在PSII初始动力学中的可能参与。共振拉曼测量将尝试直接探测初始电荷分离态的产生，克服高度重叠的电子吸收特征的限制。结合电子谱的细微差异和共振增强带来的选择性，以及带电和中性颜料的振动谱的差异，应该可以以更少的模糊性检测电荷分离状态。严格理解生物光合系统中的初级电子转移反应是完全理解自然太阳能转换的关键之一。被称为光系统II （PSII）的蛋白质复合物负责绿色植物利用光能为水中氧气的生产提供燃料的能力。PSII蛋白复合体与第二复合体光系统I （PSI）协同作用，将二氧化碳转化为碳水化合物。在本研究项目中，最先进的激光技术将用于研究光系统II （PSII）的光引发电子转移反应。本研究的总体目标是获得控制绿色植物光合作用效率和稳健性的因素的详细了解。＊＊＊