MODELS OF THE PHOTOSYNTHETIC WATER OXIDATION CENTER

迄今公认的金属最重要的生物学作用 锰(Mn)是它在水氧化中心的参与 催化水转化为氧气的气体 绿色植物和蓝藻的光合作用装置。这 反应代表了大气中氧气的来源 喘息的生命。WOC由氧化物桥联的Mn4聚集体组成 水到氧的转化是在未知的结构 是由一种目前未知的机制完成的。的目标是 这一计划是为了有助于阐明结构 这一制度的同一性和作用机制。相信 MN4聚集体是热力学稳定的实体，能够 在多肽环境之外独立存在 它自然地存在，这个程序正在寻求这一点的合成 利用无机合成程序和简单锰的集合体 试剂。对适当类型的群集的综合访问 化学已经实现，初步产品正在开发中 用更多的技术进行了研究，数据正在 获取更高级别的精度，比 天然的WOC-Mn位置。主要目的是研究稳定性。 原生生物所采用的所有不同氧化水平的物种 在催化循环中的WOC位置，以允许评估 发生的结构和性质的变化。终极的 目的是实现天然底物的转化，即 水氧化成O2气体。生物反应的重现 在受控的实验室条件下使用合成骨料 允许获得机械信息的可能性和 检测瞬变中间体是最终的，也是最重要的 消除氧气的步骤。

The most important biological role yet recognized for the metal manganese (Mn) is its involvement within the Water Oxidation Center that catalyzes the conversion of water to oxygen gas within the photosynthetic apparatus of green plants and cyanobacteria. This reaction represents the source of atmospheric oxygen for supporting respiring life. The WOC consists of an oxide-bridged Mn4 aggregate of unknown structure at which the water-to-oxygen transformation is accomplished by a currently unknown mechanism. The objective of this program is to contribute to the elucidation of the structural identity and mechanism of action of this system. Believing that the Mn4 aggregate is a thermodynamically-stable entity capable of independent existence outside the polypeptide environment in which it naturally resides, this program is seeking the synthesis of this aggregate using inorganic synthesis procedures and simple Mn reagents. Synthetic access into the appropriate type of cluster chemistry has already been achieved and initial products are being studied with a greater number of techniques, and data are being obtained to a higher level of precision, than is possible for the native WOC Mn site. The major objective is the study of stable species at all the various oxidation levels adopted by the native WOC site during the catalytic cycle to allow assessment of the changes in structure and properties that occur. The ultimate objective is to accomplish the native substrate transformation viz water oxidation to O2 gas. Reproduction of the biological reaction under controlled laboratory conditions using synthetic aggregates allows the possibility of obtaining mechanistic information and detecting transient intermediates for the final and all-important step of elimination of oxygen gas.