ON THE MECHANISM OF [NIFE]-HYDROGENASES

这个子项目是利用资源的许多研究子项目之一。 由NIH/NCRR资助的中心拨款提供。对子项目的主要支持 子项目的首席调查员可能是由其他来源提供的， 包括美国国立卫生研究院的其他来源。为子项目列出的总成本可能 表示该子项目使用的中心基础设施的估计数量， 不是由NCRR赠款提供给次级项目或次级项目工作人员的直接资金。 《自然》杂志利用分子氢作为能源的方法是基于自己的一套催化剂。其中两种被称为[FeFe]和[NiFe]氢酶，它们含有作为催化中心的双核金属核，而第三种被称为[Fe]氢酶的氢酶起源于单核。虽然这些酶的主要结构特征已经从蛋白质结晶学研究中获得，但与生物制氢或消耗氢有关的催化机制的重要细节仍不清楚。这种信息的缺乏是由于一个特殊的问题：X射线结晶学实际上对这些酶的底物是盲目的，例如，如果氢原子与金属原子配位或处于直接邻位，则对它们是盲目的。另一个迫切需要的信息的缺乏与[NiFe]氢酶有关，这些酶是在氧化的未准备阶段分离出来的。在Ni-B阶段，羟基或氧代配体被确定为连接Ni和Fe的第三个桥梁，但由于酶的氧化损伤，采用Ni-A阶段的酶内部的确切桥接情况仍然是一个有争议的主题。这种损伤导致不同修饰物种的叠加，其中一种被认为是氢过氧基或过氧基桥体系，无法明确地解决。

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. Primary support for the subproject and the subproject's principal investigator may have been provided by other sources, including other NIH sources. The Total Cost listed for the subproject likely represents the estimated amount of Center infrastructure utilized by the subproject, not direct funding provided by the NCRR grant to the subproject or subproject staff. Natures approach towards utilizing molecular hydrogen as an energy source is based on an own set of catalysts. Two of them which are termed as [FeFe] and [NiFe] hydrogenases contain binuclear metal cores as catalytic sites, whereas the third one termed [Fe] hydrogenase is mononuclear in origin. Though principal structural features of these enzymes have been obtained from protein crystallographic investigations important details of the catalytic mechanisms associated with biological hydrogen production or consumption are still not known. This lack of information is due to a particular problem: X-ray crystallography is practically blind for the substrate of these enzymes, e.g. for hydrogen atoms if they are coordinated to metal atoms or situated in their direct neighborship. Another lack of urgently needed information is associated with the [NiFe] hydrogenases which are isolated in oxidized unready stages. In the case of the Ni-B stage, a hydroxo or oxo ligand has been identified as a third bridge connecting Ni and Fe, but the exact bridging situation within the enzyme adopting the Ni-A stage is still the subject of a controversial debate due to oxidation damage of the enzyme. This damage results in a superposition of differently modified species, one of which is proposed as a hydroperoxo or peroxo bridge system which cannot be resolved unambiguously.