title: Anion protection of CuZnSOD during peroxidative activity with H(2)O(2).
abstract: The "peroxidase" activity of the copper-zinc superoxide dismutase is a poorly sustained activity because of the competing inactivation of the enzyme. New evidence suggests that the bound oxidant may be partitioning between oxidizing the enzyme or oxidizing small anions. At constant peroxide, nitrite and azide only partially protect the enzyme (50%) against loss of copper(I) and inactivation up to one anion per copper. Beyond that level, there is no further protection. Bicarbonate ion also protects, but larger amounts are required. These data suggest that there is significant oxidation of the enzyme even in the presence of the small anions and therefore the formation of the bound oxidant cannot be sustained in a true catalytic process.
authors.affiliation: Department of Chemistry, California State University, Northridge, California 91330-8262, USA.
authors.forename: S L
authors.initials: SL
authors.lastname: Jewett
authors.forename: H K
authors.initials: HK
authors.lastname: Olmsted
authors.forename: J A
authors.initials: JA
authors.lastname: Marach
authors.forename: F
authors.initials: F
authors.lastname: Rojas
authors.forename: K
authors.initials: K
authors.lastname: Silva
mesh_terms: D000818:Animals; D000838:Anions; D001665:Binding Sites; D002244:Carbon / Q000737:chemistry; D002254:Carbonates / Q000737:chemistry; D002417:Cattle; D003497:Cyclic N-Oxides / Q000737:chemistry; D005609:Free Radicals; D006861:Hydrogen Peroxide / Q000737:chemistry / Q000378:metabolism*; D006863:Hydrogen-Ion Concentration; D008099:Liver / Q000201:enzymology; D008956:Models, Chemical; D013053:Spectrophotometry; D013482:Superoxide Dismutase / Q000737:chemistry / Q000378:metabolism*; D013997:Time Factors
chemical_list: D000838:Anions; D002254:Carbonates; D003497:Cyclic N-Oxides; D005609:Free Radicals; C017245:5,5-dimethyl-1-pyrroline-1-oxide; D002244:Carbon; D006861:Hydrogen Peroxide; D013482:Superoxide Dismutase