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Purification and characterization of an iron superoxide dismutase from the nitrogen‐fixing Azotobacter vinelandii
Author(s) -
Pagani Silvia,
Colnaghi Rita,
Palagi Arianna,
Negri Armando
Publication year - 1995
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/0014-5793(94)01339-3
Subject(s) - azotobacter vinelandii , superoxide dismutase , isoelectric point , chemistry , hydrogen peroxide , enzyme , biochemistry , dismutase , nitrogen , nitrogen fixation , nitrogenase , organic chemistry
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.