MODELS OF THE PHOTOSYNTHETIC WATER OXIDATION CENTER

金属最重要的生物学作用 锰（Mn）是其参与水氧化中心 催化水转化为氧气， 绿色植物和蓝藻的光合机构。 这 反应代表了支持大气氧的来源 呼吸的生命 WOC由氧化物桥接的Mn4聚集体组成 未知的结构，水到氧的转化是 是由目前未知的机制完成的。 的目标 该程序有助于阐明结构 该系统的特性和作用机制。 相信 Mn 4聚集体是一种化学稳定实体，其能够 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种合成， 骨料采用无机合成程序和简单锰 试剂 合成访问适当类型的集群 化学已经实现，初步产品正在 研究了更多的技术，数据正在被 获得更高的精度水平，比可能的 天然WOC Mn位点。 主要目标是研究稳定的 物种在所有不同的氧化水平所采用的本地 催化循环期间的WOC现场，以评估 发生的结构和性质的变化。 最终 目标是完成自然衬底转换，即 水氧化成氧气。 生物反应的再现 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， 检测最后也是最重要的 消除氧气步骤。

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.