ExPASy Proteomics Server

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NiceZyme View of ENZYME: EC 1.17.3.2

Accepted Name

Xanthine oxidase.

Alternative Name(s)

Hypoxanthine oxidase.

Hypoxanthine-xanthine oxidase.

Hypoxanthine:oxygen oxidoreductase.

Schardinger enzyme.

Xanthine oxidoreductase.

Xanthine:O(2) oxidoreductase.

Xanthine:xanthine oxidase.

Reaction catalysed

Xanthine + H(2)O + O(2) <=> urate + H(2)O(2)

Cofactor(s)

FAD; Iron-sulfur; Molybdopterin.

Comment(s)

Also oxidizes hypoxanthine, some other purines and pterins, and aldehydes (i.e. possesses the activity of EC 1.2.3.1).
Under some conditions the product is mainly superoxide rather than peroxide: R-H + H(2)O + 2 O(2) = ROH + 2 O(2)(.-) + 2 H(+).
The enzyme from animal tissues can be converted into EC 1.17.1.4.
That from liver exists in vivo mainly as the dehydrogenase form, but can be converted into the oxidase form by storage at -20 degrees Celsius, by treatment with proteolytic enzymes or with organic solvents, or by thiol reagents such as Cu(2+), N-ethylmaleamide or 4-mercuribenzoate.
The effect of thiol reagents can be reversed by thiols such as 1,4- dithioerythritol.
EC 1.17.1.4 can also be converted into this enzyme by EC 1.8.4.7 in the presence of glutathione disulfide.
The Micrococcus enzyme can use ferredoxin as acceptor.
Formerly EC 1.1.3.22 and EC 1.2.3.2.

Cross-references

PROSITE

BRENDA

EC2PDB

PRIAM enzyme-specific profiles

KEGG Ligand Database for Enzyme Nomenclature

IUBMB Enzyme Nomenclature