EC - Factor independent urate hydroxylase

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IntEnz Enzyme Nomenclature


Accepted name:
factor independent urate hydroxylase
Other names:
uric acid oxidase
uricase II
urate oxidase
Systematic name:
urate:oxygen oxidoreductase



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

Enzymes and pathways: NC-IUBMB , BRENDA , DIAGRAM , ExplorEnz , ENZYME@ExPASy , KEGG , MetaCyc , UniPathway
Protein domains and families: PROSITE:PDOC00315
Structural data: CSA , EC2PDB
Gene Ontology: GO:0004846
CAS Registry Number: 9002-12-4
UniProtKB/Swiss-Prot: (32) [show] [UniProt]


  1. London, M. and Hudson, P.B.
    Purification and properties of solubilized uricase.
    Biochim. Biophys. Acta 21: 290-298 (1956).
  2. Mahler, H.R., Hübscher, G. and Baum, H.
    Studies on uricase. I. Preparation, purification, and properties of a cuproprotein.
    J. Biol. Chem. 216: 625-641 (1955).
  3. Robbins, K.C., Barnett, E.L. and Grant, N.H.
    Partial purification of porcine liver uricase.
    J. Biol. Chem. 216: 27-35 (1955). [PMID: 13252004]
  4. Kahn, K. and Tipton, P.A.
    Spectroscopic characterization of intermediates in the urate oxidase reaction.
    Biochemistry 37: 11651-11659 (1998). [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: 947-952 (1997). [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: 4094-4100 (2003). [PMID: 12680763]

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