title: Magnetic studies of the four-iron high-potential, non-heme protein from Chromatium vinosum.
abstract: Extensive EPR studies on high-potential, iron-sulfur protein from Chromatium vinosum indicate that the singular spectrum of this four-iron, non-heme protein consists of a superposition of three distinct signals; namely, two principal signals of equal weight, one reflecting axial and the other rhombic symmetry, and a third nearly isotropic minority component. In addition, magnetic susceptibility experiments on two oxidation states of the protein from 4.2 to approx. 260 degrees K indicate antiferromagnetic exchange coupling between iron atoms. Possible origins of the complex EPR signals are discussed, and a preferred model that is consistent with EPR, magnetic susceptibility, NMR, X-ray, and Mössbauer data is presented.
mesh_terms: D001426:Bacterial Proteins / Q000032:analysis; D001665:Binding Sites; D002844:Chromatium / Q000032:analysis*; D004578:Electron Spin Resonance Spectroscopy; D007501:Iron / Q000032:analysis*; D008280:Magnetics; D008667:Metalloproteins / Q000032:analysis; D011485:Protein Binding; D011487:Protein Conformation; D013057:Spectrum Analysis
chemical_list: D001426:Bacterial Proteins; D008667:Metalloproteins; D007501:Iron