CO 2 , not [12pt]{minimal}{amsmath}{wasysym} {amsfonts} {amssymb} {amsbsy}{mathrsfs}{}{-69pt}{document}{equation*}{HCO}₃⁻{equation*}{document}, facilitates oxidations by Cu,Zn superoxide dismutase plus H 2 O 2

The Cu,Zn superoxide dismutase catalyzes [12pt]{minimal} {amsmath} {wasysym} {amsfonts} {amssymb} {amsbsy} {mathrsfs} {}{-69pt} {document} {equation*}{HCO}₃⁻{equation*}{document} -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 [12pt]{minimal} {amsmath} {wasysym} {amsfonts} {amssymb} {amsbsy} {mathrsfs} {}{-69pt} {document} {equation*}{HCO}₃⁻{equation*}{document} to [12pt]{minimal} {amsmath} {wasysym} {amsfonts} {amssymb} {amsbsy} {mathrsfs} {}{-69pt} {document} {equation*}{CO}₃^{{·}-}{equation*}{document} , which diffuses into the bulk solution and there oxidizes diverse substrates. We now find that CO 2 rather than [12pt]{minimal} {amsmath} {wasysym} {amsfonts} {amssymb} {amsbsy} {mathrsfs} {}{-69pt} {document} {equation*}{HCO}₃⁻{equation*}{document} facilitates the peroxidations catalyzed by Cu,Zn superoxide dismutase. This fact was shown by a lag in the rate of peroxidation of NADPH when [12pt]{minimal} {amsmath} {wasysym} {amsfonts} {amssymb} {amsbsy} {mathrsfs} {}{-69pt} {document} {equation*}{NaHCO}₃⁻{equation*}{document} 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.