NI ENZYME EXAFS BEYOND THE CU EDGE

这个子项目是利用由NIH/NCRR资助的中心拨款提供的资源的许多研究子项目之一。子项目和调查员(PI)可能从另一个NIH来源获得了主要资金，因此可能会出现在其他CRISE条目中。列出的机构是针对中心的，而不一定是针对调查员的机构。长硫弧菌中的Ni-Fe氢酶在一个不寻常的Ni-Fe簇上催化分子氢的可逆氧化。不活跃的A型酶的晶体结构显示，镍由两个末端的半胱氨硫键连接，以及两个半胱氨酸硫键连接到一个Fe(CO)(CN)2单元，Ni-Fe距离为2.95？另一个桥式轻原子也以这种形式出现(命名为“氧”)。在相关氢酶的还原形式和活性形式的结构中，桥联原子似乎不存在。准确地了解Ni-Fe中心的原子间距对于理解催化机理是很重要的。然而，EXAFS分析、X射线结构和理论计算之间对Ni-Fe位置的结构并不完全一致。关于氢酶中Ni-Fe位结构的争论引起了我们用Ni EXAF重新检查Ni位的兴趣

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Ni-Fe Hydrogenase in Desulfovibrio gigas catalyzes the reversible oxidation of molecular hydrogen at an unusual Ni-Fe cluster. The crystal structures for the inactive form A enzyme reveal a Ni ligated by two terminal cysteine sulfurs, as well as two cysteine sulfurs that bridge to an Fe(CO)(CN)2 unit, with a Ni-Fe distance of 2.95 ¿¿ An additional bridging light atom is also seen in this form (assigned as "oxygen"). The bridging atom appears absent in structures of the reduced and active forms of related hydrogenases. A precise understanding of the interatomic distances at the Ni-Fe center is important for an understanding of the catalytic mechanism. However, there is not complete agreement between EXAFS analyses, X-ray structures, and theoretical calculations on the structure of the Ni-Fe site. The controversies on the structure of Ni-Fe site in hydrogenase has raised our interest to reexamine the Ni site by Ni EXAF