IUBMB Enzyme Nomenclature


Accepted name: 2-oxo-4-hydroxy-4-carboxy-5-ureidoimidazoline decarboxylase

Reaction: 5-hydroxy-2-oxo-4-ureido-2,5-dihydro-1H-imidazole-5-carboxylate = (S)-allantoin + CO2

For diagram of reaction click here.

Glossary: 5-hydroxy-2-oxo-4-ureido-2,5-dihydro-1H-imidazole-5-carboxylate = 2-oxo-4-hydroxy-4-carboxy-5-ureidoimidazoline

Other name(s): OHCU decarboxylase; hpxQ (gene name); PRHOXNB (gene name)

Systematic name: 5-hydroxy-2-oxo-4-ureido-2,5-dihydro-1H-imidazole-5-carboxylate carboxy-lyase [(S)-allantoin-forming]

Comments: This enzyme is part of the pathway from urate to (S)-allantoin, which is present in bacteria, plants and animals (but not in humans).

Links to other databases: BRENDA, EXPASY, KEGG, MetaCyc, PDB, CAS registry number:


1. Ramazzina, I., Folli, C., Secchi, A., Berni, R. and Percudani, R. Completing the uric acid degradation pathway through phylogenetic comparison of whole genomes. Nat. Chem. Biol. 2 (2006) 144-148. [PMID: 16462750]

2. Cendron, L., Berni, R., Folli, C., Ramazzina, I., Percudani, R. and Zanotti, G. The structure of 2-oxo-4-hydroxy-4-carboxy-5-ureidoimidazoline decarboxylase provides insights into the mechanism of uric acid degradation. J. Biol. Chem. 282 (2007) 18182-18189. [PMID: 17428786]

3. Kim, K., Park, J. and Rhee, S. Structural and functional basis for (S)-allantoin formation in the ureide pathway. J. Biol. Chem. 282 (2007) 23457-23464. [PMID: 17567580]

4. French, J.B. and Ealick, S.E. Structural and mechanistic studies on Klebsiella pneumoniae 2-oxo-4-hydroxy-4-carboxy-5-ureidoimidazoline decarboxylase. J. Biol. Chem. 285 (2010) 35446-35454. [PMID: 20826786]

[EC created 2014]

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