The Mechanism of Water Splitting and Oxygen Evolution in Photosynthesis

水氧化成分子氧是一种 与光合作用有关的特征反应， 高等植物 光量子产生的激发 光系统导致电子一次一个地转移 直到从两个水分子中移走四个电子， 产生氧气。 涉及的化学中间体 在高还原电位下转移电子， 储存产生氧气所需的氧化当量， 研究了 锰参与了水的分解 酶和X射线光谱学 同步辐射实验室被用来确定 氧化态，连接和周围的局部结构 MN. 与使用EPR光谱的研究一起，结果 证实了Mn氧化态的直接参与 水分解过程的变化。 这项建议旨在 为了表征锰结合位点的性质， 首先通过识别相关蛋白质， 确定参与提供的特定氨基酸 锰的配体，希望在不久的将来， 表征所涉及的分子种类，通过使用 电子-原子核和电子-电子双共振， 和X射线光谱学，以及 水被掺入到水分解酶中 在最终形成和释放氧气之前。 知识 这一过程将是最有用的发展人工 利用太阳能将水 转化为分子氧和氢燃料

The oxidation of water to molecular oxygen is a characteristic reaction associated with photosynthesis in higher plants. Light quanta producing excitation of the photosystem result in the transfer of electrons one at a time until four electrons are removed from two water molecules to produce oxygen. The chemical intermediates involved in transferring electrons at high reduction potentials and in storing the oxiding equivalents needed to yield oxygen are being investigated. Manganese is involved in the water-splitting enzyme, and X-ray spectroscopy at the Stanford Synchrotron Radiation Laboratory is being used to determine the oxidation state, ligation and local structure around the Mn. Together with studies using EPR spectroscopy, results have verified the direct participation of Mn oxidation state changes in the water-splitting process. This proposal aims to characterize the nature of the manganese binding site, first by identifying the proteins involved and then in determining the specific amino acids involved in providing ligands to the manganese., In the near future it is hoped to characterize the molecular species involved, through the use of electron-nuclear and electron-electron double resonance, and X-ray spectroscopy as well the nature of the way in which water becomes incorporated into the water-splitting enzyme prior to the final formation and release of oxygen. Knowledge of this process will be most useful in developing artificial systems whereby solar energy can be used to convert water into molecular oxygen and hydrogen fuel.***