Influence of the [2Fe]H Subcluster Environment on the Properties of Key Intermediates in the Catalytic Cycle of [FeFe] Hydrogenases: Hints for the Rational Design of Synthetic Catalysts
Influence of the [2Fe]H Subcluster Environment on the Properties of Key Intermediates in the Catalytic Cycle of [FeFe] Hydrogenases: Hints for the Rational Design of Synthetic Catalysts
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DOI：
10.1002/anie.200900494
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发表时间：
2009-01-01
影响因子：
16.6
通讯作者：
De Gioia, Luca
中科院分区：
文献类型：
--
作者：
Bruschi, Maurizio;Greco, Claudio;De Gioia, Luca
在[FeFe]氢化酶的活性位点发现了一种特殊的Fe6S6簇，称为h簇。H-团簇可以被描述为一个经典的Fe4S4团簇，通过半胱氨酸残基的硫原子连接到一个生物学上不寻常的双核铁团簇，通常被称为[2Fe] H亚团簇在亚簇中，两个铁离子由S-CH2-X-CH2-S配体桥接。机理考虑[2]和能量势垒计算[3]支持二（硫甲基）胺（dtma， X= NH）作为螯合配体的存在。然而，也有人提出X可能对应于CH2（丙烷- 1,3 -二硫代酸酯，pdt）或O（二（硫甲基）醚，dtme）。[1,4]有人指出，在催化生成H2的[FeFe]氢化酶循环中，原则上可以在[2Fe] H中形成末端和桥接氢化物配体的中间体事实上，对[2Fe] H亚簇模型的研究表明，热力学上最稳定的形式通常对应于μ-氢化物然而，实验结果[7]和DFT计算[3]表明，只有末端氢化物在H2生成中具有足够的活性，证实了在[FeFe]-氢化酶催化循环中只有末端氢化物是短暂形成的假设。[3,5]在这种情况下，一个问题不仅与更好地理解[FeFe]氢化酶的化学性质特别相关，而且与
A peculiar Fe6S6 cluster, referred to as the H-cluster, is found in the active site of [FeFe] hydrogenases. The H-cluster can be described as a classical Fe4S4 cluster that is bridged, through the sulfur atom of a cysteine residue, to a biologically unusual binuclear Fe cluster, usually referred to as the [2Fe] H subcluster.[1] In the subcluster, the two iron ions are bridged by a S-CH2-X-CH2-S ligand. Mechanistic considerations [2] and computation of energy barriers [3] support the presence of di (thiomethyl) amine (dtma, X= NH) as the chelating ligand. However, it has been also proposed that X might correspond to CH2 (propane-1, 3-dithiolate, pdt) or O (di (thiomethyl) ether, dtme).[1, 4]It has been noted that, in principle, intermediates with both terminal and bridging hydride ligands in [2Fe] H might be formed in the catalytic cycle of [FeFe] hydrogenases leading to H2 formation.[5] Indeed, investigations of models of the [2Fe] H subcluster revealed that the thermodynamically most stable forms generally correspond to μ-hydride species.[6] However, experimental results [7] and DFT calculations [3] have shown that only terminal-hydride species are sufficiently reactive in H2 production, corroborating the hypothesis that only terminal-hydride species are transiently formed in the [FeFe]-hydrogenase catalytic cycle.[3, 5] In this scenario, a question particularly relevant not only to better understanding of the chemistry of [FeFe] hydrogenases, but also for the