Direct Observation of an Iron-Bound Terminal Hydride in [FeFe]-Hydrogenase by Nuclear Resonance Vibrational Spectroscopy.
Direct Observation of an Iron-Bound Terminal Hydride in [FeFe]-Hydrogenase by Nuclear Resonance Vibrational Spectroscopy.
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DOI：
10.1021/jacs.7b00686
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发表时间：
2017-03-29
影响因子：
15
通讯作者：
Cramer SP
中科院分区：
文献类型：
--
作者：
Reijerse EJ;Pham CC;Pelmenschikov V;Gilbert-Wilson R;Adamska-Venkatesh A;Siebel JF;Gee LB;Yoda Y;Tamasaku K;Lubitz W;Rauchfuss TB;Cramer SP
[FeFe]-氢化酶以极高的效率催化质子可逆还原为分子氢。活性位点（“H-簇”）由通过桥接半胱氨酸连接到由CN-和CO配体配位的[2Fe]H亚位点的[4Fe-4S]H簇组成，该配体具有二硫醇-胺部分，其充当蛋白质质子通道和催化远端铁位点（Fed）之间的质子穿梭。虽然有广泛的共识，铁结合的终端氢化物物种必须发生在催化机制，这样的物种从来没有直接观察到实验。在这里，我们提出了FTIR和核共振振动光谱（NRVS）实验结合密度泛函理论（DFT）计算的[FeFe]-氢化酶的变体缺乏胺质子穿梭，这是稳定的推定氢化物状态。的NRVS光谱明确地显示终端Fe-H物种的弯曲模式完全符合广泛接受的模型的催化循环。
[FeFe]-hydrogenases catalyze the reversible reduction of protons to molecular hydrogen with extremely high efficiency. The active site (“H-cluster”) consists of a [4Fe–4S]H cluster linked through a bridging cysteine to a [2Fe]H subsite coordinated by CN− and CO ligands featuring a dithiol-amine moiety that serves as proton shuttle between the protein proton channel and the catalytic distal iron site (Fed). Although there is broad consensus that an iron-bound terminal hydride species must occur in the catalytic mechanism, such a species has never been directly observed experimentally. Here, we present FTIR and nuclear resonance vibrational spectroscopy (NRVS) experiments in conjunction with density functional theory (DFT) calculations on an [FeFe]-hydrogenase variant lacking the amine proton shuttle which is stabilizing a putative hydride state. The NRVS spectra unequivocally show the bending modes of the terminal Fe–H species fully consistent with widely accepted models of the catalytic cycle.
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