Infrared Spectroscopic Studies of the Photosynthetic Oxygen-Evolving Complex

9418164巴里红外光谱技术将用于研究光合放氧复合物，光系统II的结构和功能之间的关系。 这些实验将集中在含锰的催化位点和33 kDa的锰稳定外源蛋白。 水的氧化是一个四电子事件。 光系统II反应中心的含锰催化位点积累这四种氧化当量，并通过一系列的五种“S”状态循环。“振动光谱将用于获得有关锰簇和光氧化反应中心发生的结构变化的信息。 还将采用红外光谱法研究33 kDa蛋白的结构和功能作用。 该提案有三个目标：A）使用差示红外光谱来测量和鉴定光系统II锰簇氧化后发生的结构变化; B）测试当33 kDa蛋白质中发生二级结构变化的假设当该外源亚基结合到光系统II反应中心时; C）使用差示红外光谱法来确定33 kDa蛋白质的去除是否影响伴随锰簇氧化的结构变化。 植物的光合作用包括将光能转化为化学能。 这一过程是通过电子在膜结合蛋白中的多步转移来实现的。 通过这种电子转移，在整个膜上建立了相对稳定的电荷分离。 这种电荷分离是能量存储事件，并且由光能驱动。 电子的最终供体是水;从水中去除电子的过程导致氧的释放。氧气的产生对于维持地球上的人类生命至关重要。 这项提案将资助对负责产生氧气的膜相关蛋白的研究。 产生氧的化学反应发生在四个锰原子的簇中。 通过使用振动光谱，我们将获得有关锰簇的结构和结合位点的新信息，以及有关在该金属簇发生的化学反应的信息。 振动光谱是研究这些过程的理想技术，因为它对微小的结构变化非常敏感。 ***

9418164 Barry The technique of infrared spectroscopy will be used to investigate the relationship between structure and function in the photosynthetic oxygen-evolving complex, photosystem II. These experiments will focus on the manganese-containing catalytic site and on the 33 kDa manganese-stabilizing extrinsic protein. The oxidation of water is a four electron event. The manganese- containing catalytic site of the photosystem II reaction center accumulates these four oxidizing equivalents and cycles through a series of five "S states." Vibrational spectroscopy will be used to obtain information concerning the structural changes that occur in the manganese cluster and in the reaction center upon photooxidation. Infrared spectroscopy will also be employed in order to investigate the structure and functional role of the 33 kDa protein. This proposal has three objectives: A) to use difference infrared spectroscopy to measure and to identify the structural changes that occur upon oxidation of the photosystem II manganese cluster; B) to test the hypothesis that secondary structure changes occur in the 33 kDa protein when this extrinsic subunits binds to the photosystem II reaction center; C) to use difference infrared spectroscopy to determine if removal of the 33 kDa protein influences the structural changes that accompany oxidation of the manganese cluster. %%% Photosynthesis in plants involves the conversion of light energy into chemical energy. This process is carried out be the multi- step transfer of electrons in membrane associated proteins. Through this transfer of electrons, a relatively stable separation of charge is built up across the membrane. This charge separation is the energy storage event and is driven by the energy of light. The ultimate donor of electrons is water; the process of removal of electrons from water results in the liberation of oxygen. This oxygen production is critical for the maintenance of human life on earth. This propo sal will fund studies of the membrane associated protein that is responsible for the production of oxygen. Oxygen producing chemistry occurs at a cluster of four manganese atoms. Through the use of vibrational spectroscopy, we will obtain new information concerning the structure and binding site of the manganese cluster, as well as concerning the chemistry that occurs at this metal cluster. Vibrational spectroscopy is the ideal technique to use to investigate these processes, since it is exquisitely sensitive to small structural alterations. ***