Bridging Hydride at Reduced H-Cluster Species in [FeFe]-Hydrogenases Revealed by Infrared Spectroscopy, Isotope Editing, and Quantum Chemistry
Bridging Hydride at Reduced H-Cluster Species in [FeFe]-Hydrogenases Revealed by Infrared Spectroscopy, Isotope Editing, and Quantum Chemistry
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DOI：
10.1021/jacs.7b07548
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发表时间：
2017-09-06
影响因子：
15
通讯作者：
Haumann, Michael
中科院分区：
文献类型：
--
作者：
Mebs, Stefan;Senger, Moritz;Haumann, Michael
[FeFe]-氢化酶含有H-2-转化辅因子（H-簇），其中典型的[4Fe-4S]簇与具有三个一氧化碳（CO）和两个氰化物（CN-）配体的独特二铁位点连接（例如，在氧化状态下，Hox）。有很多争论是否还原和氢键结合可能会导致在一个单一的（Hred）或双（Hsred）减少H-簇物种的二铁网站的替代旋转异构体结构。我们采用红外光谱电化学和位点选择性同位素编辑监测CO/CN伸缩振动[FeFe]氢化酶HYDA 1从莱茵衣藻。密度泛函理论计算产生的振动模式的双原子配体的可能的H-簇结构。实验和计算IF的相关性分析。光谱促进了Hred和Hsred的分配与桥接氢化物在二铁网站的结构。明显的配体旋转在亩H结合似乎排除Hred和Hsred作为催化中间体。只有具有保守的H-团簇几何特征的μ CO配体的状态可能参与快速的H-2营业额。
[FeFe]-Hydrogenases contain a H-2-converting cofactor (H-cluster) in which a canonical [4Fe-4S] cluster is linked to a unique diiron site with three carbon monoxide (CO) and two cyanide (CN-) ligands (e.g., in the oxidized state, Hox). There has been much debate whether reduction and hydrogen binding may result in alternative rotamer structures of the diiron site in a single (Hred) or double (Hsred) reduced H-cluster species. We employed infrared spectro-electrochemistry and site-selective isotope editing to monitor the CO/CN- stretching vibrations in [FeFe]-hydrogenase HYDA1 from Chlamydomonas reinhardtii. Density functional theory calculations yielded vibrational modes of the diatomic ligands for conceivable H-cluster structures. Correlation analysis of experimental and computational IF. spectra has facilitated an assignment of Hred and Hsred to structures with a bridging hydride at the diiron site. Pronounced ligand rotation during mu H binding seems to exclude Hred and Hsred as catalytic intermediates. Only states with a conservative H-cluster geometry featuring a mu CO ligand are likely involved in rapid H-2 turnover.