title: The Fe-V Cofactor of Vanadium Nitrogenase Contains an Interstitial Carbon Atom.
abstract: The first direct evidence is provided for the presence of an interstitial carbide in the Fe-V cofactor of Azotobacter vinelandii vanadium nitrogenase. As for our identification of the central carbide in the Fe-Mo cofactor, we employed Fe Kβ valence-to-core X-ray emission spectroscopy and density functional theory calculations, and herein report the highly similar spectra of both variants of the cofactor-containing protein. The identification of an analogous carbide, and thus an atomically homologous active site in vanadium nitrogenase, highlights the importance and influence of both the interstitial carbide and the identity of the heteroatom on the electronic structure and catalytic activity of the enzyme.
authors.affiliation: Department of Molecular Theory and Spectroscopy, Max-Planck-Institut für Chemische Energiekonversion, Stiftstrasse 34-36, 45470 Mülheim an der Ruhr (Germany).|Department of Chemistry, University of Washington, Box 351700, Seattle, WA 98195-1700 (USA).
authors.forename: Julian A
authors.initials: JA
authors.lastname: Rees
authors.affiliation: Department of Molecular Theory and Spectroscopy, Max-Planck-Institut für Chemische Energiekonversion, Stiftstrasse 34-36, 45470 Mülheim an der Ruhr (Germany).|Present address: Science Institute, University of Iceland, Dunhaga 3, 107 Reykjavik (Iceland).
authors.forename: Ragnar
authors.initials: R
authors.lastname: Bjornsson
authors.affiliation: Institut für Biochemie and BIOSS Centre for Biological Signalling Studies, Albert-Ludwigs-Universität Freiburg, Albertstrasse 21, 79104 Freiburg (Germany).
authors.forename: Julia
authors.initials: J
authors.lastname: Schlesier
authors.affiliation: Institut für Biochemie and BIOSS Centre for Biological Signalling Studies, Albert-Ludwigs-Universität Freiburg, Albertstrasse 21, 79104 Freiburg (Germany).
authors.forename: Daniel
authors.initials: D
authors.lastname: Sippel
authors.affiliation: Institut für Biochemie and BIOSS Centre for Biological Signalling Studies, Albert-Ludwigs-Universität Freiburg, Albertstrasse 21, 79104 Freiburg (Germany).
authors.forename: Oliver
authors.initials: O
authors.lastname: Einsle
authors.affiliation: Department of Molecular Theory and Spectroscopy, Max-Planck-Institut für Chemische Energiekonversion, Stiftstrasse 34-36, 45470 Mülheim an der Ruhr (Germany). serena.debeer@cec.mpg.de.|Department of Chemistry and Chemical Biology, Cornell University, Ithaca, NY 14853 (USA). serena.debeer@cec.mpg.de.
authors.forename: Serena
authors.initials: S
authors.lastname: DeBeer
mesh_terms: D016948:Azotobacter vinelandii / Q000737:chemistry* / Q000378:metabolism; D002244:Carbon / Q000737:chemistry* / Q000378:metabolism; D003067:Coenzymes / Q000737:chemistry* / Q000378:metabolism; D007501:Iron / Q000737:chemistry* / Q000378:metabolism; D009591:Nitrogenase / Q000737:chemistry* / Q000378:metabolism; D014639:Vanadium / Q000737:chemistry* / Q000378:metabolism
chemical_list: D003067:Coenzymes; D014639:Vanadium; D002244:Carbon; D007501:Iron; D009591:Nitrogenase
keywords: X-ray spectroscopy; cofactors; nitrogen fixation; nitrogenases; vanadium