Live Chat
Today's Hours: 8:00am - 10:00pm
Lane Medical Library

Search

Filter Results

Did You Mean:

Search Results

Sort by
relevance
  • Journal
    Digital Access
    Provider
    Version
    HighWire
    v. 1-, 1926-
    PubMed Central
    v. 1-92, 1926-2007.
    Ovid
    v. 85, no. 3-v. 92, Sept. 2001-07.
    Print Access Request
    Location
    Version
    Call Number
    Items
    Stored offsite. Please request print.
    v. 1-93, 1926-2008.
    118
  • Article
    Hodgson EK, Fridovich I.
    Biochemistry. 1975 Dec 02;14(24):5294-9.
    Bovine erythrocyte superoxide dismutase was slowly and irreversibly inactivated by hydrogen peroxide. The rate of this inactivation was directly dependent upon the concentrations of both H2O2 and of enzyme, and its second-order rate constant at pH 10.0 and 25 degrees was 6.7 M-1 sec-1. Inactivation was preceded by a bleaching due to rapid reduction of Cu2+ on the enzyme, and following this there was a gradual reappearance of a new absorption in the visible region, which was coincident with the loss of catalytic activity. Inactivation of the enzyme was pH-dependent and indicated an essential ionization whose pKa was approximately 10.2. Replacement of H2O by D2O raised this pKa but did not diminish the catalytic activity of superoxide dismutase, measured at pH 10.0. Several compounds, including xanthine, urate, formate, and azide, protected the enzyme against inactivation by H2O2. Alcohols and benzoate, which scavenge hydroxyl radical, did not protect. Compounds with special affinity for singlet oxygen were similarly ineffective. The data were interpreted in terms of the reduction of the enzyme-bound Cu2+ to Cu+, by H2O2, followed by a Fenton's type reaction of the Cu+ with additional H2O2. This would generate Cu2+-OH- or its ionized equivalent, Cu2+-O--, which could then oxidatively attack an adjacent histidine and thus inactivate the enzyme. Compounds which protected the enzyme could have done so by reacting with the bound oxidant, in competition with the adjacent histidine.
    Digital Access Access Options