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Takeshi Hiromoto Oliver Pilak Marco Salomone Stagni Eberhard Warkentin Seigo Shima Ulrich Ermler 《FEBS letters》2009,583(3):585-771
[Fe]-hydrogenase is one of three types of enzymes known to activate H2. Crystal structure analysis recently revealed that its active site iron is ligated square-pyramidally by Cys176-sulfur, two CO, an “unknown” ligand and the sp2-hybridized nitrogen of a unique iron-guanylylpyridinol-cofactor. We report here on the structure of the C176A mutated enzyme crystallized in the presence of dithiothreitol (DTT). It suggests an iron center octahedrally coordinated by one DTT-sulfur and one DTT-oxygen, two CO, the 2-pyridinol’s nitrogen and the 2-pyridinol’s 6-formylmethyl group in an acyl-iron ligation. This result led to a re-interpretation of the iron ligation in the wild-type. 相似文献
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[Fe]-Hydrogenase catalyzes the reversible activation of H2. CO and CN− inhibit this enzyme with low affinity (Ki ≅ 0.1 mM) by binding to the iron site of the bound iron-guanyrylpyridinol cofactor. We report here that isocyanides, which are formally isoelectronic with CO and CN−, strongly inhibit [Fe]-hydrogenase (Ki as low as 1 nM). The [NiFe]- and [FeFe]-hydrogenases tested were not inhibited by isocyanides. UV–Vis and infrared spectra revealed that the isocyanides bind to the iron center of [Fe]-hydrogenase. The inhibition kinetics are in agreement with the proposed catalytic mechanism, including the open/closed conformational change of the enzyme. 相似文献
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