NI ENZYME EXAFS BEYOND THE CU EDGE

该子项目是利用NIH/NCRR资助的中心赠款提供的资源的许多研究子项目之一。子项目和研究者（PI）可能从另一个NIH来源获得了主要资金，因此可以在其他CRISP条目中表示。所列机构为中心，不一定是研究者所在机构。脱硫弧菌中的Ni-Fe氢化酶催化分子氢在一个不寻常的Ni-Fe簇上的可逆氧化。失活形式A酶的晶体结构显示由两个末端半胱氨酸硫连接的Ni，以及桥接到Fe（CO）（CN）2单元的两个半胱氨酸硫，Ni-Fe距离为2.95。桥连原子在相关氢化酶的还原和活性形式的结构中似乎不存在。准确理解Ni-Fe中心的原子间距离对于理解催化机理是重要的。然而，EXAFS分析，X-射线结构和理论计算的Ni-Fe网站的结构之间并不完全一致。氢化酶中Ni-Fe中心结构的争论引起了我们用Ni-EXAF重新研究Ni中心的兴趣

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