How formaldehyde inhibits hydrogen evolution by [FeFe]-hydrogenases: Determination by 13C ENDOR of direct Fe-C coordination and order of electron and proton transfers

Andreas Bachmeier, Julian Esselborn, Suzannah V. Hexter, Tobias Krämer, Kathrin Klein, Thomas Happe, John E. McGrady, William K. Myers, Fraser A. Armstrong

Research output: Contribution to journalArticlepeer-review

6 Citations (Scopus)


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.

Original languageEnglish
Pages (from-to)5381-5389
Number of pages9
JournalJournal of the American Chemical Society
Issue number16
Publication statusPublished - 29 Apr 2015

ASJC Scopus subject areas

  • Chemistry(all)
  • Catalysis
  • Biochemistry
  • Colloid and Surface Chemistry


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