Terminal Hydride Species in [FeFe]-Hydrogenases are Vibrationally Coupled to the Active Site Environment

Cindy C. Pham, David W. Mulder, Vladimir Pelmenschikov, Paul W. King, Michael W. Ratzloff, Hongxin Wang, Nakul Mishra, Esen E. Alp, Jiyong Zhao, Michael Y. Hu, Kenji Tamasaku, Yoshitaka Yoda, Stephen P. Cramer

Research output: Contribution to journalArticlepeer-review

25 Scopus Citations

Abstract

A combination of nuclear resonance vibrational spectroscopy (NRVS), FTIR spectroscopy, and DFT calculations was used to observe and characterize Fe−H/D bending modes in CrHydA1 [FeFe]-hydrogenase Cys-to-Ser variant C169S. Mutagenesis of cysteine to serine at position 169 changes the functional group adjacent to the H-cluster from a -SH to -OH, thus altering the proton transfer pathway. The catalytic activity of C169S is significantly reduced compared to that of native CrHydA1, presumably owing to less efficient proton transfer to the H-cluster. This mutation enabled effective capture of a hydride/deuteride intermediate and facilitated direct detection of the Fe−H/D normal modes. We observed a significant shift to higher frequency in an Fe−H bending mode of the C169S variant, as compared to previous findings with reconstituted native and oxadithiolate (ODT)-substituted CrHydA1. On the basis of DFT calculations, we propose that this shift is caused by the stronger interaction of the -OH group of C169S with the bridgehead -NH- moiety of the active site, as compared to that of the -SH group of C169 in the native enzyme.

Original languageAmerican English
Pages (from-to)10605-10609
Number of pages5
JournalAngewandte Chemie - International Edition
Volume57
Issue number33
DOIs
StatePublished - 2018

Bibliographical note

Publisher Copyright:
© 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim

NREL Publication Number

  • NREL/JA-2700-71499

Keywords

  • enzyme catalysis
  • FTIR spectroscopy
  • hydride species
  • hydrogenases
  • nuclear resonance vibrational spectroscopy

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