Bicarbonate as a New Cofactor of Water Oxidase

这一合作项目的重点是阐明碳酸氢盐的作用。 (Bc)水氧化酶(WOC)的功能/结构组织。 我们合作产生的先前联合研究表明，BC是一个关键 组装WOC的无机核心所需的组件，特别是 Mn2+离子的结合和光氧化。卑诗省也有潜力 认识无机岩心生物成因的意义 在第一个02年的进化过程中产生了光合作用的有机体。至 研究BC与Bc直接相互作用(结扎)的可能性 WOC、EPR、Endor、ESE-Endor和FT-LR的(Mn4Ca1Clx)核心 在更换BC 12年后，将研究堆芯的特性 C-和13C-甲酸盐，13C-重碳酸盐和硼酸盐 APO-WOC制剂中的WOC及其无机辅因子。一个可能的角色是 BC在四电子(产生02)之间“切换”到 水氧化的双电子(产生H202)机理，将 使用鲁米诺-过氧化物酶测定法(其灵敏度为 在俄罗斯组中显著增加)。BC的一个可能角色是 还将检测WOC的过氧化氢酶活性。电化学法 与BC等弱阴离子的锰络合物及其催化性能 向WOC提供电子并催化氢的分解 将对过氧化氢进行研究，以了解碳酸氢盐的特性 对WOC的影响。包括人类在内的所有需氧生物的健康取决于 在这些过程中，由于水氧化是主要的可再生来源 大气中的氧气，而过氧化氢酶则可防止由 过氧化氢，一种强有力的生物毒素。这个项目的具体目标是 与上级NIH项目的目标直接相关 光合作用水氧化酶。这项研究将主要在俄罗斯作为 延长美国国立卫生研究院5R01GM39932-10号拨款

This collaborative project is focused on elucidation of the role of bicarbonate (BC) in the functional/structural organization of the water oxidase (WOC). Prior joint studies arising from our collaboration has shown that BC is a key component needed for assembly of the inorganic core of the WOC, particularly the binding and photo-oxidation of Mn 2+ ions. BC also has potential significance for understanding the origin of biogenesis of the inorganic core during evolution of the first 02 producing photosynthetic organisms. To investigate the possibility of direct interaction (ligation) of BC to the (Mn4Ca1Clx) core of the WOC, the EPR, ENDOR, ESE-ENDOR and FT-lR characteristics of the core will be investigated after replacement of BC for 12 C- and 13C-formate, 13C- bicarbonate and borate during reconstitution of the WOC from apo-WOC preparations and the inorganic cofactors. A possible role for BC in "switching" between the four-electron (with production of 02) to the two-electron (with production of H202) mechanism of water oxidation, will be investigated using the luminol-peroxidase assay (the sensitivity of which has been considerably increased in the Russian group). A possible role for BC in the catalase activity of the WOC will also be examined. Electrochemistry of manganese complexes with BC and other weak anions, and their capabilities to donate electrons to the WOC and to catalyse the decomposition of hydrogen peroxide will be studied to understand the specificity of the bicarbonate effect on the WOC. The health of all aerobic organisms, including man, depends upon these processes, since water oxidation is the dominant renewable source of atmospheric oxygen, while catalase protects against oxidative damage caused by hydrogen peroxide, a potent biological toxin. The specific aims of this project are directly related to the aims of the parent NIH project "Catalases and photosynthetic water oxidase." The research will be mainly done in Russia as an extension of NIH grant #5R01GM39932-1O