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ENZYME

ENZYME entry: EC 1.17.3.2

Accepted Name
xanthine oxidase
Alternative Name(s)
hypoxanthine oxidase
hypoxanthine-xanthine oxidase
Schardinger enzyme
xanthine oxidoreductase
Reaction catalysed
H2O + O2 + xanthine <=> H2O2 + urate
Comment(s)
  • Also oxidizes hypoxanthine, some other purines and pterins, and aldehydes, but is distinct from EC 1.2.3.1.
  • Under some conditions the product is mainly superoxide rather than peroxide: R-H + H2O + 2 O2 = ROH + 2 O2(.-) + 2 H(+).
  • The mammallian enzyme predominantly exists as an NAD-dependent dehydrogenase (EC 1.17.1.4).
  • During purification the enzyme is largely converted to the O2-dependent xanthine oxidase form (EC 1.17.3.2).
  • The conversion can be triggered by several mechanisms, including the oxidation of cysteine thiols to form disulfide bonds (which can be catalyzed by EC 1.8.4.7 in the presence of glutathione disulfide) or limited proteolysis, which results in irreversible conversion.
  • The conversion can also occur in vivo.
  • Formerly EC 1.1.3.22 and EC 1.2.3.2.
Cross-references
BRENDA 1.17.3.2
EC2PDB 1.17.3.2
ExplorEnz 1.17.3.2
PRIAM enzyme-specific profiles 1.17.3.2
KEGG Ligand Database for Enzyme Nomenclature 1.17.3.2
IUBMB Enzyme Nomenclature 1.17.3.2
IntEnz 1.17.3.2
MEDLINE Find literature relating to 1.17.3.2
MetaCyc 1.17.3.2
Rhea expert-curated reactions 1.17.3.2
UniProtKB/Swiss-Prot
P80457, XDH_BOVIN P47990, XDH_CHICK Q9MYW6, XDH_FELCA
P47989, XDH_HUMAN Q00519, XDH_MOUSE P22985, XDH_RAT

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