IUBMB Enzyme Nomenclature


Accepted name: 5-(carboxyamino)imidazole ribonucleotide synthase

Reaction: ATP + 5-amino-1-(5-phospho-D-ribosyl)imidazole + HCO3- = ADP + phosphate + 5-carboxyamino-1-(5-phospho-D-ribosyl)imidazole

For diagram, click here

Other name(s): N5-CAIR synthetase; N5-carboxyaminoimidazole ribonucleotide synthetase; PurK

Systematic name: 5-amino-1-(5-phospho-D-ribosyl)imidazole:carbon-dioxide ligase (ADP-forming)

Comments: In Escherichia coli, this enzyme, along with EC, 5-(carboxyamino)imidazole ribonucleotide mutase, is required to carry out the single reaction catalysed by EC, phosphoribosylaminoimidazole carboxylase, in vertebrates. Belongs to the ATP grasp protein superfamily [3]. Carboxyphosphate is the putative acyl phosphate intermediate. Involved in the late stages of purine biosynthesis.

Links to other databases: BRENDA, EXPASY, KEGG, Metacyc, PDB, CAS registry number: 255379-40-9


1. Meyer, E., Leonard, N.J., Bhat, B., Stubbe, J. and Smith, J.M. Purification and characterization of the purE, purK, and purC gene products: identification of a previously unrecognized energy requirement in the purine biosynthetic pathway. Biochemistry 31 (1992) 5022-5032. [PMID: 1534690]

2. Mueller, E.J., Meyer, E., Rudolph, J., Davisson, V.J. and Stubbe, J. N5-Carboxyaminoimidazole ribonucleotide: evidence for a new intermediate and two new enzymatic activities in the de novo purine biosynthetic pathway of Escherichia coli. Biochemistry 33 (1994) 2269-2278. [PMID: 8117684]

3. Thoden, J.B., Kappock, T.J., Stubbe, J. and Holden, H.M. Three-dimensional structure of N5-carboxyaminoimidazole ribonucleotide synthetase: a member of the ATP grasp protein superfamily. Biochemistry 38 (1999) 15480-15492. [PMID: 10569930]

[EC created 2006]

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