Activation Thermodynamics and H/D Kinetic Isotope Effect of the Hox to HredH+ Transition in [FeFe] Hydrogenase

Michael W. Ratzloff, Molly B. Wilker, David W. Mulder, Carolyn E. Lubner, Hayden Hamby, Katherine A. Brown, Gordana Dukovic, Paul W. King

Research output: Contribution to journalArticlepeer-review

21 Scopus Citations


Molecular complexes between CdSe nanocrystals and Clostridium acetobutylicum [FeFe] hydrogenase I (CaI) enabled light-driven control of electron transfer for spectroscopic detection of redox intermediates during catalytic proton reduction. Here we address the route of electron transfer from CdSe→CaI and activation thermodynamics of the initial step of proton reduction in CaI. The electron paramagnetic spectroscopy of illuminated CdSe:CaI showed how the CaI accessory FeS cluster chain (F-clusters) functions in electron transfer with CdSe. The Hox→HredH+ reduction step measured by Fourier-transform infrared spectroscopy showed an enthalpy of activation of 19 kJ mol-1 and a ∼2.5-fold kinetic isotope effect. Overall, these results support electron injection from CdSe into CaI involving F-clusters, and that the Hox→HredH+ step of catalytic proton reduction in CaI proceeds by a proton-dependent process.

Original languageAmerican English
Pages (from-to)12879-12882
Number of pages4
JournalJournal of the American Chemical Society
Issue number37
StatePublished - 2017

Bibliographical note

Publisher Copyright:
© 2017 American Chemical Society.

NREL Publication Number

  • NREL/JA-2700-68424


  • H2 catalysis
  • hydrogenase
  • thermodynamics


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