title: E.p.r.-spectroscopic studies on the molybdenum-iron site of nitrogenase from Clostridium pasteurianum.
abstract: The e.p.r. spectroscopy of the nitrogenase molybdenum-iron protein from Clostridium pasteurianum was re-investigated. The sharpness of the delta Ms = +/- 3 g'z peak from the +/- 3/2 Kramer's doublet enables the observation and quantification of incompletely resolved hyperfine splittings from the stable magnetic nuclei 95Mo and 57Fe in samples enriched in these isotopes. No couplings to 1H or 17O could be discerned by examination of spectra from samples exchanged into 2H2O and H2(17)O respectively. Simulation of the spectrum from 95Mo-enriched samples yields a hyperfine coupling of 2.9 MHz, and indicates that the earlier electron-nuclear-double-resonance-derived estimate of 8.1 +/- 0.2 MHz is substantially in error.
authors.affiliation: Exxon Research and Engineering Co., Annandale, NJ 08801.
authors.forename: G N
authors.initials: GN
authors.lastname: George
authors.forename: R E
authors.initials: RE
authors.lastname: Bare
authors.forename: H Y
authors.initials: HY
authors.lastname: Jin
authors.forename: E I
authors.initials: EI
authors.lastname: Stiefel
authors.forename: R C
authors.initials: RC
authors.lastname: Prince
mesh_terms: D001665:Binding Sites; D003013:Clostridium / Q000201:enzymology*; D004578:Electron Spin Resonance Spectroscopy; D007501:Iron; D008982:Molybdenum; D009591:Nitrogenase / Q000032:analysis*; D010088:Oxidoreductases
chemical_list: D008982:Molybdenum; D007501:Iron; D010088:Oxidoreductases; D009591:Nitrogenase; C029130:nitrogenase reductase