Spectroscopic Characterization of the Bridging Amine in the Active Site of [FeFe] Hydrogenase Using Isotopologues of the H-Cluster

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• 作者：Agnieszka Adamska-Venkatesh ; Souvik Roy ; Judith F. Siebel ; Trevor R. Simmons ; Marc Fontecave ; Vincent Artero ; Edward Reijerse ; Wolfgang Lubitz
• 刊名：Journal of the American Chemical Society
• 出版年：2015
• 出版时间：October 14, 2015
• 年：2015
• 卷：137
• 期：40
• 页码：12744-12747
• 全文大小：330K
• ISSN：1520-5126

文摘

The active site of [FeFe] hydrogenase contains a catalytic binuclear iron subsite coordinated by CN^{鈥?/sup> and CO ligands as well as a unique azadithiolate (adt2鈥?/sup>) bridging ligand. It has been established that this binuclear cofactor is synthesized and assembled by three maturation proteins HydE, -F, and -G. By means of in vitro maturation in the presence of 15N- and 13C-labeled tyrosine it has been shown that the CN鈥?/sup> and CO ligands originate from tyrosine. The source of the bridging adt2鈥?/sup> ligand, however, remains unknown. In order to identify the nitrogen of the bridging amine using HYSCORE spectroscopy and distinguish its spectroscopic signature from that of the CN鈥?/sup> nitrogens, we studied three isotope-labeled variants of the H-cluster (15N-adt2鈥?/sup>/C14N鈥?/sup>, 15N-adt2鈥?/sup>/C15N鈥?/sup>, and 14N-adt2鈥?/sup>/C15N鈥?/sup>) and extracted accurate values of the hyperfine and quadrupole couplings of both CN鈥?/sup> and adt2鈥?/sup> nitrogens. This will allow an evaluation of isotopologues of the H-cluster generated by in vitro bioassembly in the presence of various 15N-labeled potential precursors as possible sources of the bridging ligand.}