title: Purification and characterization of an iron superoxide dismutase from the nitrogen-fixing Azotobacter vinelandii.
abstract: Two electrophoretically distinct forms of superoxide dismutase (SOD; EC 1.15.1.1) which show different inhibition patterns to hydrogen peroxide have been identified in Azotobacter vinelandii. The SOD inhibited by hydrogen peroxide was purified to homogeneity, and turned out to be an iron superoxide dismutase. The enzyme is present in only one molecular form with an isoelectric point of 4.1, and it is composed of two identical subunits with an apparent molecular weight of 21,000 Da. Spectroscopic analyses indicated that this enzyme contains ferric iron (1.4-1.6 mol/mol protein) in the typical high-spin form present in other prokaryotic Fe-SODs. N-Terminal sequence alignments (up to the 49th residue) showed that A. vinelandii Fe-SOD has high similarity with other prokaryotic Fe-SODs.
authors.affiliation: Dipartimento di Scienze Molecolari Agroalimentari, CISMI, University of Milano, Italy.
authors.forename: S
authors.initials: S
authors.lastname: Pagani
authors.forename: R
authors.initials: R
authors.lastname: Colnaghi
authors.forename: A
authors.initials: A
authors.lastname: Palagi
authors.forename: A
authors.initials: A
authors.lastname: Negri
mesh_terms: D000595:Amino Acid Sequence; D016948:Azotobacter vinelandii / Q000201:enzymology*; D004578:Electron Spin Resonance Spectroscopy; D007525:Isoelectric Focusing; D008969:Molecular Sequence Data; D017386:Sequence Homology, Amino Acid; D013482:Superoxide Dismutase / Q000302:isolation & purification* / Q000378:metabolism
chemical_list: D013482:Superoxide Dismutase