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    How Formaldehyde Inhibits Hydrogen Evolution by [FeFe]-Hydrogenases: Determination by13C ENDOR of Direct Fe–C Coordination and Order of Electron and Proton Transfers

    Bachmeier, Andreas and Esselborn, Julian and Hexter, Suzannah V. and Krämer, Tobias and Klein, Kathrin and Happe, Thomas and McGrady, John E. and Myers, William K. and Armstrong, Fraser A. (2015) How Formaldehyde Inhibits Hydrogen Evolution by [FeFe]-Hydrogenases: Determination by13C ENDOR of Direct Fe–C Coordination and Order of Electron and Proton Transfers. Journal of the American Chemical Society, 137 (16). pp. 5381-5389. ISSN 0002-7863

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    Formaldehyde (HCHO), a strong electrophile and a rapid and reversible inhibitor of hydrogen production by [FeFe]-hydrogenases, is used to identify the point in the catalytic cycle at which a highly reactive metal-hydrido species is formed. Investigations of the reaction of Chlamydomonas reinhardtii [FeFe]-hydrogenase with formaldehyde using pulsed-EPR techniques including electron–nuclear double resonance spectroscopy establish that formaldehyde binds close to the active site. Density functional theory calculations support an inhibited super-reduced state having a short Fe–13C bond in the 2Fe subsite. The adduct forms when HCHO is available to compete with H+ transfer to a vacant, nucleophilic Fe site: had H+ transfer already occurred, the reaction of HCHO with the Fe-hydrido species would lead to methanol, release of which is not detected. Instead, Fe-bound formaldehyde is a metal-hydrido mimic, a locked, inhibited form analogous to that in which two electrons and only one proton have transferred to the H-cluster. The results provide strong support for a mechanism in which the fastest pathway for H2 evolution involves two consecutive proton transfer steps to the H-cluster following transfer of a second electron to the active site.

    Item Type: Article
    Keywords: Formaldehyde; Inhibits; Hydrogen; Evolution; FeFe-Hydrogenases; Determination; 13C ENDOR; Direct Fe–C Coordination; Order; Electron; Proton Transfers;
    Academic Unit: Faculty of Science and Engineering > Chemistry
    Faculty of Science and Engineering > Research Institutes > Hamilton Institute
    Item ID: 15492
    Identification Number:
    Depositing User: Tobias Kraemer
    Date Deposited: 14 Feb 2022 17:09
    Journal or Publication Title: Journal of the American Chemical Society
    Publisher: American Chemical Society
    Refereed: Yes
    Use Licence: This item is available under a Creative Commons Attribution Non Commercial Share Alike Licence (CC BY-NC-SA). Details of this licence are available here

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