title: Direct Observation of an Iron-Bound Terminal Hydride in [FeFe]-Hydrogenase by Nuclear Resonance Vibrational Spectroscopy.
abstract: [FeFe]-hydrogenases catalyze the reversible reduction of protons to molecular hydrogen with extremely high efficiency. The active site ("H-cluster") consists of a [4Fe-4S]Hcluster linked through a bridging cysteine to a [2Fe]Hsubsite coordinated by CN-and CO ligands featuring a dithiol-amine moiety that serves as proton shuttle between the protein proton channel and the catalytic distal iron site (Fed). Although there is broad consensus that an iron-bound terminal hydride species must occur in the catalytic mechanism, such a species has never been directly observed experimentally. Here, we present FTIR and nuclear resonance vibrational spectroscopy (NRVS) experiments in conjunction with density functional theory (DFT) calculations on an [FeFe]-hydrogenase variant lacking the amine proton shuttle which is stabilizing a putative hydride state. The NRVS spectra unequivocally show the bending modes of the terminal Fe-H species fully consistent with widely accepted models of the catalytic cycle.
authors.affiliation: Max-Planck-Institut für Chemische Energiekonversion , Stiftstrasse 34-36, 45470 Mülheim, Germany.
authors.forename: Edward J
authors.initials: EJ
authors.lastname: Reijerse
authors.affiliation: Department of Chemistry, University of California , Davis, California 95616, United States.
authors.forename: Cindy C
authors.initials: CC
authors.lastname: Pham
authors.affiliation: Institut für Chemie, Technische Universität Berlin , 10623 Berlin, Germany.
authors.forename: Vladimir
authors.initials: V
authors.lastname: Pelmenschikov
authors.affiliation: School of Chemical Sciences, University of Illinois at Urbana-Champaign , Urbana, Illinois 61801, United States.
authors.forename: Ryan
authors.initials: R
authors.lastname: Gilbert-Wilson
authors.affiliation: Max-Planck-Institut für Chemische Energiekonversion , Stiftstrasse 34-36, 45470 Mülheim, Germany.
authors.forename: Agnieszka
authors.initials: A
authors.lastname: Adamska-Venkatesh
authors.affiliation: Max-Planck-Institut für Chemische Energiekonversion , Stiftstrasse 34-36, 45470 Mülheim, Germany.
authors.forename: Judith F
authors.initials: JF
authors.lastname: Siebel
authors.affiliation: Department of Chemistry, University of California , Davis, California 95616, United States.
authors.forename: Leland B
authors.identifier: 0000-0002-5817-3997
authors.initials: LB
authors.lastname: Gee
authors.affiliation: Materials Dynamics Laboratory, RIKEN SPring-8 , Hyogo 679-5148, Japan.
authors.forename: Yoshitaka
authors.initials: Y
authors.lastname: Yoda
authors.affiliation: Materials Dynamics Laboratory, RIKEN SPring-8 , Hyogo 679-5148, Japan.
authors.forename: Kenji
authors.initials: K
authors.lastname: Tamasaku
authors.affiliation: Max-Planck-Institut für Chemische Energiekonversion , Stiftstrasse 34-36, 45470 Mülheim, Germany.
authors.forename: Wolfgang
authors.identifier: 0000-0001-7059-5327
authors.initials: W
authors.lastname: Lubitz
authors.affiliation: School of Chemical Sciences, University of Illinois at Urbana-Champaign , Urbana, Illinois 61801, United States.
authors.forename: Thomas B
authors.identifier: 0000-0003-2547-5128
authors.initials: TB
authors.lastname: Rauchfuss
authors.affiliation: Department of Chemistry, University of California , Davis, California 95616, United States.
authors.forename: Stephen P
authors.initials: SP
authors.lastname: Cramer
mesh_terms: D006864:Hydrogenase / Q000737:chemistry* / Q000378:metabolism; D007501:Iron / Q000737:chemistry* / Q000378:metabolism; D007506:Iron-Sulfur Proteins / Q000737:chemistry* / Q000378:metabolism; D009682:Magnetic Resonance Spectroscopy; D008968:Molecular Conformation; D011789:Quantum Theory; D017550:Spectroscopy, Fourier Transform Infrared; D014867:Water / Q000737:chemistry / Q000378:metabolism
chemical_list: D007506:Iron-Sulfur Proteins; D014867:Water; D007501:Iron; C118830:iron hydrogenase; D006864:Hydrogenase