title: An atomic-level mechanism for molybdenum nitrogenase. Part 1. Reduction of dinitrogen.
abstract: The properties of the Fe and Mo sites of the iron-molybdenum cofactor of nitrogenase with respect to binding and activation of N(2) have been studied by molecular mechanics calculations on the local protein environment and by density functional theory (DFT) calculations on subsections of the cofactor. The DFT calculations indicate that the homocitrate ligand of the cofactor can become monodentate on reduction, allowing N(2) to bind at Mo. In addition, the neighboring Fe atom plays a crucial role in N(2) reduction by stabilizing the initial reduced N(2) species and by facilitating cleavage of the N-N bond. The various possible isomers for partially reduced N(2) intermediates have been compared by DFT, and a detailed model for the reduction of N(2) is developed based on these results, together with chemical precedents and the available biochemical data for nitrogenase.
authors.affiliation: Computational Biology Group, John Innes Centre, Norwich Research Park, Colney Lane, Norwich NR4 7UH, United Kingdom. marcus.durrant@bbsrc.ac.uk
authors.forename: Marcus C
authors.initials: MC
authors.lastname: Durrant
mesh_terms: D019943:Amino Acid Substitution; D001059:Apoproteins / Q000737:chemistry* / Q000378:metabolism*; D016948:Azotobacter vinelandii / Q000378:metabolism; D001426:Bacterial Proteins; D001665:Binding Sites; D005973:Glutamine; D007711:Klebsiella pneumoniae / Q000378:metabolism; D008024:Ligands; D008958:Models, Molecular; D008983:Molybdoferredoxin / Q000737:chemistry* / Q000378:metabolism*; D016297:Mutagenesis, Site-Directed; D009589:Nitrogen Oxides / Q000493:pharmacokinetics*; D010084:Oxidation-Reduction; D011487:Protein Conformation; D011994:Recombinant Proteins / Q000737:chemistry / Q000378:metabolism
chemical_list: D001059:Apoproteins; D001426:Bacterial Proteins; D008024:Ligands; D008983:Molybdoferredoxin; D009589:Nitrogen Oxides; D011994:Recombinant Proteins; C065636:nitrogenase apomolybdenum-iron protein, Bacteria; D005973:Glutamine