title: A tetrameric iron superoxide dismutase from the eucaryote Tetrahymena pyriformis.
abstract: An iron-containing superoxide dismutase has been purified from the protozoan Tetrahymena pyriformis. It has a molecular weight of 85,000 and is composed of four subunits of equal size. The tetramer contains 2.5 g atoms of ferric iron. Visible absorption and electron spin resonance spectra closely resemble those of other iron-containing superoxide dismutases. The amino acid sequence of the iron superoxide dismutase was determined. Each subunit is made up of 196 residues, corresponding to a molecular weight of 22,711. Comparison of the primary structure with the known sequences of other iron-containing superoxide dismutases reveals a relatively low degree of identity (33-34%). However, a higher percentage identity is found with mammalian manganese-containing superoxide dismutases (41-42%). The amino acid sequence is discussed in consideration of residues that may distinguish iron from manganese or dimeric from tetrameric superoxide dismutases.
authors.affiliation: Dipartimento di Scienze Biochimiche, Università La Sapienza, Roma, Italy.
authors.forename: D
authors.initials: D
authors.lastname: Barra
authors.forename: M E
authors.initials: ME
authors.lastname: Schininà
authors.forename: F
authors.initials: F
authors.lastname: Bossa
authors.forename: K
authors.initials: K
authors.lastname: Puget
authors.forename: P
authors.initials: P
authors.lastname: Durosay
authors.forename: A
authors.initials: A
authors.lastname: Guissani
authors.forename: A M
authors.initials: AM
authors.lastname: Michelson
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D002852:Chromatography, Ion Exchange; D004578:Electron Spin Resonance Spectroscopy; D004926:Escherichia coli / Q000201:enzymology / Q000235:genetics; D006801:Humans; D046911:Macromolecular Substances; D008969:Molecular Sequence Data; D008970:Molecular Weight; D013053:Spectrophotometry; D013482:Superoxide Dismutase / Q000235:genetics / Q000302:isolation & purification* / Q000378:metabolism; D013769:Tetrahymena pyriformis / Q000201:enzymology* / Q000235:genetics
chemical_list: D046911:Macromolecular Substances; D013482:Superoxide Dismutase