Dioxygen Sensitivity of [Fe]‐Hydrogenase in the Presence of Reducing Substrates |
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| Authors: | Gangfeng Huang Dr Tristan Wagner Dr Ulrich Ermler Dr Eckhard Bill Dr Kenichi Ataka Dr Seigo Shima |
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| Affiliation: | 1. Max-Planck-Institut für terrestrische Mikrobiologie, Marburg, Germany;2. Max-Planck-Institut für Biophysik, Frankfurt/Main, Germany;3. Max-Planck-Institut für Chemische Energiekonversion, Mülheim, Germany;4. Department of Physics, Freie Universit?t Berlin, Berlin, Germany |
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| Abstract: | Mono‐iron hydrogenase (Fe]‐hydrogenase) reversibly catalyzes the transfer of a hydride ion from H2 to methenyltetrahydromethanopterin (methenyl‐H4MPT+) to form methylene‐H4MPT. Its iron guanylylpyridinol (FeGP) cofactor plays a key role in H2 activation. Evidence is presented for O2 sensitivity of Fe]‐hydrogenase under turnover conditions in the presence of reducing substrates, methylene‐H4MPT or methenyl‐H4MPT+/H2. Only then, H2O2 is generated, which decomposes the FeGP cofactor; as demonstrated by spectroscopic analyses and the crystal structure of the deactivated enzyme. O2 reduction to H2O2 requires a reductant, which can be a catalytic intermediate transiently formed during the Fe]‐hydrogenase reaction. The most probable candidate is an iron hydride species; its presence has already been predicted by theoretical studies of the catalytic reaction. The findings support predictions because the same type of reduction reaction is described for ruthenium hydride complexes that hydrogenate polar compounds. |
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| Keywords: | [Fe]-hydrogenase enzyme catalysis H2 hydrogenation O2 sensitivity |
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