IUBMB Enzyme Nomenclature


Accepted name: hydroxyisourate hydrolase

Reaction: 5-hydroxyisourate + H2O = 5-hydroxy-2-oxo-4-ureido-2,5-dihydro-1H-imidazole-5-carboxylate

For diagram click here.

Other name(s): HIUHase; 5-hydroxyisourate hydrolase

Systematic name: 5-hydroxyisourate amidohydrolase

Comments: The reaction is the first stage in the conversion of 5-hydroxyisourate into S-allantoin. This reaction will also occur spontaneously but more slowly.

Links to other databases: BRENDA, EXPASY, KEGG, Metacyc, PDB, CAS registry number: 255885-20-2


1. Raychaudhuri, A. and Tipton, P.A. A familiar motif in a new context: the catalytic mechanism of hydroxyisourate hydrolase. Biochemistry 42 (2003) 6848-6852.[PMID: 12779339]

2. Raychaudhuri, A. and Tipton, P.A. Cloning and expression of the gene for soybean hydroxyisourate hydrolase. Localization and implications for function and mechanism. Plant Physiol. 130 (2002) 2061-2068. [PMID: 12481089]

3. Sarma, A.D., Serfozo, P., Kahn, K. and Tipton, P.A. Identification and purification of hydroxyisourate hydrolase, a novel ureide-metabolizing enzyme. J. Biol. Chem. 274 (1999) 33863-33865. [PMID: 10567345]

[EC created 2004]

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