A tetrameric iron superoxide dismutase from the eucaryote Tetrahymena pyriformis.
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.
Barra
D
D
Dipartimento di Scienze Biochimiche, Università La Sapienza, Roma, Italy.
Schininà
M E
ME
Bossa
F
F
Puget
K
K
Durosay
P
P
Guissani
A
A
Michelson
A M
AM
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
D046911:Macromolecular Substances; D013482:Superoxide Dismutase