title: Iron K-edge X-ray-absorption spectroscopy of the iron-vanadium cofactor of the vanadium nitrogenase from Azotobacter chroococcum.
abstract: Iron K-edge e.x.a.f.s. data for the iron-vanadium cofactor (FeVaco) from Azotobacter chroococcum vanadium nitrogenase reported here provide further evidence for the structural similarity between this and the iron-molybdenum nitrogenase cofactor (FeMoco) from Klebsiella pneumoniae molybdenum nitrogenase [Arber, Flood, Garner, Gormal, Hasnain & Smith (1988) Biochem. J. 252, 421-425]. The e.x.a.f.s. data are consistent with the vanadium being present in a V-Fe-S cluster, thus confirming that the N-methylformamide extract of the VFe protein component of A. chroococcum vanadium nitrogenase does indeed contain a polynuclear metal-sulphur cluster. Additionally, a long Fe-Fe distance is observed as 0.369 nm, demonstrating the presence of a long-range order in the cluster.
authors.affiliation: Synchrotron Radiation Research Division, S.E.R.C. Daresbury Laboratory, Warrington, U.K.
authors.forename: I
authors.initials: I
authors.lastname: Harvey
authors.forename: J M
authors.initials: JM
authors.lastname: Arber
authors.forename: R R
authors.initials: RR
authors.lastname: Eady
authors.forename: B E
authors.initials: BE
authors.lastname: Smith
authors.forename: C D
authors.initials: CD
authors.lastname: Garner
authors.forename: S S
authors.initials: SS
authors.lastname: Hasnain
mesh_terms: D001395:Azotobacter / Q000201:enzymology*; D008667:Metalloproteins / Q000032:analysis*; D009591:Nitrogenase / Q000032:analysis*; D013052:Spectrometry, X-Ray Emission / Q000379:methods
chemical_list: D008667:Metalloproteins; C055326:iron-vanadium cofactor; D009591:Nitrogenase