IUBMB Enzyme Nomenclature


Accepted name: factor-independent urate hydroxylase

Reaction: urate + O2 + H2O = 5-hydroxyisourate + H2O2

For diagram of reaction, click here

Other name(s): uric acid oxidase; uricase; uricase II; urate oxidase

Systematic name: urate:oxygen oxidoreductase

Comments: This enzyme was previously thought to be a copper protein, but it is now known that the enzymes from soy bean (Glycine max), the mould Aspergillus flavus and Bacillus subtilis contains no copper nor any other transition-metal ion. The 5-hydroxyisourate formed decomposes spontaneously to form allantoin and CO2, although there is an enzyme-catalysed pathway in which EC, hydroxyisourate hydrolase, catalyses the first step. The enzyme is different from EC (FAD-dependent urate hydroxylase).

Links to other databases: BRENDA, EXPASY, KEGG, Metacyc, PDB, UM-BBD, CAS registry number: 9002-12-4


1. London, M. and Hudson, P.B. Purification and properties of solubilized uricase. Biochim. Biophys. Acta 21 (1956) 290-298. [PMID: 13363909]

2. Mahler, H.R., Hübscher, G. and Baum, H. Studies on uricase. I. Preparation, purification, and properties of a cuproprotein. J. Biol. Chem. 216 (1955) 625-641. [PMID: 13271340]

3. Robbins, K.C., Barnett, E.L. and Grant, N.H. Partial purification of porcine liver uricase. J. Biol. Chem. 216 (1955) 27-35. [PMID: 13252004]

4. Kahn, K. and Tipton, P.A. Spectroscopic characterization of intermediates in the urate oxidase reaction. Biochemistry 37 (1998) 11651-11659. [PMID: 9709003]

5. Colloc'h, N., el Hajji, M., Bachet, B., L'Hermite, G., Schiltz, M., Prange, T., Castro, B. and Mornon, J.-P. Crystal structure of the protein drug urate oxidase-inhibitor complex at 2.05 Å resolution. Nat. Struct. Biol. 4 (1997) 947-952. [PMID: 9360612]

6. Imhoff, R.D., Power, N.P., Borrok, M.J. and Tipton, P.A. General base catalysis in the urate oxidase reaction: evidence for a novel Thr-Lys catalytic diad. Biochemistry 42 (2003) 4094-4100. [PMID: 12680763]

[EC created 1961, modified 2002, modified 2005, modified 2010]

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