Comparative electronic structures of nitrogenase FeMoco and FeVco.
An investigation of the active site cofactors of the molybdenum and vanadium nitrogenases (FeMoco and FeVco) was performed using high-resolution X-ray spectroscopy. Synthetic heterometallic iron-sulfur cluster models and density functional theory calculations complement the study of the MoFe and VFe holoproteins using both non-resonant and resonant X-ray emission spectroscopy. Spectroscopic data show the presence of direct iron-heterometal bonds, which are found to be weaker in FeVco. Furthermore, the interstitial carbide is found to perturb the electronic structures of the cofactors through highly covalent Fe-C bonding. The implications of these conclusions are discussed in light of the differential reactivity of the molybdenum and vanadium nitrogenases towards various substrates. Possible functional roles for both the heterometal and the interstitial carbide are detailed.
Max Planck Institute for Chemical Energy Conversion, Stiftstr. 34-36, 45470 Mülheim an der Ruhr, Germany. serena.debeer@cec.mpg.de and Department of Chemistry, University of Washington, Box 351700, Seattle, WA 98195-1700, USA. kovacs@chem.washington.edu.
Julian A
http://orcid.org/0000-0003-0883-2680
JA
Rees
Max Planck Institute for Chemical Energy Conversion, Stiftstr. 34-36, 45470 Mülheim an der Ruhr, Germany. serena.debeer@cec.mpg.de and Science Institute, University of Iceland, Dunhagi 3, 107 Reykjavik, Iceland.
Ragnar
http://orcid.org/0000-0003-2167-8374
R
Bjornsson
Max Planck Institute for Chemical Energy Conversion, Stiftstr. 34-36, 45470 Mülheim an der Ruhr, Germany. serena.debeer@cec.mpg.de.
Joanna K
JK
Kowalska
Max Planck Institute for Chemical Energy Conversion, Stiftstr. 34-36, 45470 Mülheim an der Ruhr, Germany. serena.debeer@cec.mpg.de and Centro Nacional de Pesquisa em Energia e Materiais Brazilian Synchrotron Light Laboratory - LNLS Rua Giuseppe Máximo Scolfaro, 10.000 13083-970 Campinas SP, Brazil.
Frederico A
http://orcid.org/0000-0001-8106-2892
FA
Lima
Institute for Biochemistry and BIOSS Centre for Biological Signalling Studies, Albert Ludwigs University Freiburg, Germany. einsle@bio.chemie.uni-freiburg.de.
Julia
J
Schlesier
Institute for Biochemistry and BIOSS Centre for Biological Signalling Studies, Albert Ludwigs University Freiburg, Germany. einsle@bio.chemie.uni-freiburg.de.
Daniel
D
Sippel
Max Planck Institute for Chemical Energy Conversion, Stiftstr. 34-36, 45470 Mülheim an der Ruhr, Germany. serena.debeer@cec.mpg.de.
Thomas
T
Weyhermüller
Institute for Biochemistry and BIOSS Centre for Biological Signalling Studies, Albert Ludwigs University Freiburg, Germany. einsle@bio.chemie.uni-freiburg.de.
Oliver
O
Einsle
Department of Chemistry, University of Washington, Box 351700, Seattle, WA 98195-1700, USA. kovacs@chem.washington.edu.
Julie A
JA
Kovacs
Max Planck Institute for Chemical Energy Conversion, Stiftstr. 34-36, 45470 Mülheim an der Ruhr, Germany. serena.debeer@cec.mpg.de and Department of Chemistry and Chemical Biology, Cornell University, Ithaca, NY 14853, USA.
Serena
S
DeBeer