ID   1.17.3.2
DE   xanthine oxidase.
AN   hypoxanthine oxidase.
AN   hypoxanthine-xanthine oxidase.
AN   Schardinger enzyme.
AN   xanthine oxidoreductase.
CA   H2O + O2 + xanthine = H2O2 + urate.
CC   -!- Also oxidizes hypoxanthine, some other purines and pterins,
CC       and aldehydes, but is distinct from EC 1.2.3.1.
CC   -!- Under some conditions the product is mainly superoxide rather than
CC       peroxide: R-H + H2O + 2 O2 = ROH + 2 O2(.-) + 2 H(+).
CC   -!- The mammallian enzyme predominantly exists as an NAD-dependent
CC       dehydrogenase (EC 1.17.1.4).
CC   -!- During purification the enzyme is largely converted to the
CC       O2-dependent xanthine oxidase form (EC 1.17.3.2).
CC   -!- The conversion can be triggered by several mechanisms, including the
CC       oxidation of cysteine thiols to form disulfide bonds (which can be
CC       catalyzed by EC 1.8.4.7 in the presence of glutathione disulfide) or
CC       limited proteolysis, which results in irreversible conversion.
CC   -!- The conversion can also occur in vivo.
CC   -!- Formerly EC 1.1.3.22 and EC 1.2.3.2.
DR   P80457, XDH_BOVIN  ;  P47990, XDH_CHICK  ;  Q9MYW6, XDH_FELCA  ;
DR   P47989, XDH_HUMAN  ;  Q00519, XDH_MOUSE  ;  P22985, XDH_RAT    ;
//