title: CO2, not HCO3-, facilitates oxidations by Cu,Zn superoxide dismutase plus H2O2.
abstract: The Cu,Zn superoxide dismutase catalyzes HCO(3)(-) -dependent oxidations by H(2)O(2). This activity has been shown to depend on the creation of a bound oxidant at the Cu(II) by interactions with H(2)O(2). The bound oxidant was then thought to oxidize HCO(3)(-) to CO(3)(.-), which diffuses into the bulk solution and there oxidizes diverse substrates. We now find that CO(2) rather than HCO(3)(-) facilitates the peroxidations catalyzed by Cu,Zn superoxide dismutase. This fact was shown by a lag in the rate of peroxidation of NADPH when NaHCO(3)(-) was added last and by a burst in the rate when aqueous CO(2) was added last. Both the lag and the burst were eliminated by carbonic anhydrase.
authors.affiliation: Department of Biochemistry, Duke University Medical Center, Durham, NC 27710, USA.
authors.forename: Stefan I
authors.initials: SI
authors.lastname: Liochev
authors.forename: Irwin
authors.initials: I
authors.lastname: Fridovich
mesh_terms: D001639:Bicarbonates / Q000378:metabolism; D002245:Carbon Dioxide / Q000378:metabolism; D006861:Hydrogen Peroxide / Q000378:metabolism; D066298:In Vitro Techniques; D007700:Kinetics; D009249:NADP / Q000378:metabolism; D010084:Oxidation-Reduction; D013482:Superoxide Dismutase / Q000378:metabolism*; D000072105:Superoxide Dismutase-1
chemical_list: D001639:Bicarbonates; D002245:Carbon Dioxide; D009249:NADP; D006861:Hydrogen Peroxide; D013482:Superoxide Dismutase; D000072105:Superoxide Dismutase-1