Center for Bioinformatics
Oxidoreductases | Transferases | Hydrolases | Lyases | Isomerases | Ligases

Basic Information

Enzyme Number

Official Name

xanthine oxidase

Name from literature

xanthine oxidase

Pathway from literature

nucleic acid degradation/purine catabolism

Pathway from KEGG

Nucleotide Metabolism; Purine metabolism; map00230

Xenobiotics Biodegradation and Metabolism; Drug metabolism - other enzymes; map00983

Biosynthesis of Secondary Metabolites; Caffeine metabolism; map00232


Rat (10116)

Genome localization

6q13[497811 ],


An iron-molybdenum flavoprotein (FAD) containing [2Fe-2S] centres. Also oxidizes hypoxanthine, some other purines and pterins, and aldehydes (i.e. possesses the activity of EC, aldehyde oxidase). Under some conditions the product is mainly superoxide rather than peroxide: RH + H2O + 2 O2 = ROH + 2 O2.- + 2 H+. The enzyme from animal tissues can be converted into EC, xanthine dehydrogenase. That from liver exists in vivo mainly as the dehydrogenase form, but can be converted into the oxidase form by storage at -20 _degree_C, by treatment with proteolytic enzymes or with organic solvents, or by thiol reagents such as Cu2+, N-ethylmaleimide or 4-mercuribenzoate. The effect of thiol reagents can be reversed by thiols such as 1,4-dithioerythritol. EC can also be converted into this enzyme by EC, enzyme-thiol transhydrogenase (glutathione-disulfide) in the presence of glutathione disulfide. The Micrococcus enzyme can use ferredoxin as acceptor.

Rate-limiting Description

"Although aspects of the glutathione antioxidant repertoire were similarly diminished with high-intensity xanthine oxidase stress, low-dose (long duration) xanthine oxidase stress augmented the activities of type II cell glutathione peroxidase and gamma-glutamyl transferase (the rate-limiting enzyme in glutathione synthesis)." (12780970)

Regulatory Information

Regulatory type




Gene ontology

Gene ontology

GO:0050660 (F) FAD binding [P22985 ];
GO:0051537 (F) 2 iron, 2 sulfur cluster binding [P22985 ];
GO:0030151 (F) molybdenum ion binding [P22985 ];
GO:0005506 (F) iron ion binding [P22985 ];
GO:0004855 (F) xanthine oxidase activity [P22985 ];
GO:0009055 (F) electron carrier activity [P22985 ];
GO:0005777 (C) peroxisome [P22985 ];
GO:0004854 (F) xanthine dehydrogenase activity [P22985 ];
GO:0055114 (P) oxidation reduction [P22985 ];

Subcellular localization


peroxisome [P22985 ];




Entrez Gene


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  Last Modified: 2009-03-24  
  Design by Zhao Min