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Issue 3, 2012
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Evidence for acyl–iron ligation in the active site of [Fe]-hydrogenase provided by mass spectrometry and infrared spectroscopy

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Abstract

[Fe]-hydrogenase catalyzes the reversible heterolytic cleavage of H2 and stereo-specific hydride transfer to the substrate methenyltetrahydromethanopterin in methanogenic archaea. This enzyme contains a unique iron guanylylpyridinol (FeGP) cofactor as a prosthetic group. It has recently been proposed—on the basis of crystal structural analyses of the [Fe]-hydrogenase holoenzyme—that the FeGP cofactor contains an acyliron ligation, the first one reported in a biological system. We report here that the cofactor can be reversibly extracted with acids; its exact mass has been determined by electrospray ionization Fourier transform ion cyclotron resonance mass-spectrometry. The measured mass of the intact cofactor and its gas-phase fragments are consistent with the proposed structure. The mass of the light decomposition products of the cofactor support the presence of acyliron ligation. Attenuated total reflection infrared spectroscopy of the FeGP cofactor revealed a band near wave number 1700 cm−1, which was assigned to the C[double bond, length as m-dash]O (double bond) stretching mode of the acyliron ligand.

Graphical abstract: Evidence for acyl–iron ligation in the active site of [Fe]-hydrogenase provided by mass spectrometry and infrared spectroscopy

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Supplementary files

Article information


Submitted
10 Jun 2011
Accepted
03 Oct 2011
First published
14 Nov 2011

Dalton Trans., 2012,41, 767-771
Article type
Paper

Evidence for acyliron ligation in the active site of [Fe]-hydrogenase provided by mass spectrometry and infrared spectroscopy

S. Shima, M. Schick, J. Kahnt, K. Ataka, K. Steinbach and U. Linne, Dalton Trans., 2012, 41, 767
DOI: 10.1039/C1DT11093D

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