phosphoribosyl-AMP cyclohydrolase
phosphoribosyl-AMP cyclohydrolase dimer, Methanobacterium
Identifiers
EC no.	3.5.4.19
CAS no.	37289-22-8
Databases
IntEnz	IntEnz view
BRENDA	BRENDA entry
ExPASy	NiceZyme view
KEGG	KEGG entry
MetaCyc	metabolic pathway
PRIAM	profile
PDB structures	RCSB PDB PDBe PDBsum
Gene Ontology	AmiGO / QuickGO
Search PMC articles PubMed articles NCBI proteins

In enzymology, a phosphoribosyl-AMP cyclohydrolase (EC 3.5.4.19) is an enzyme that catalyzes the chemical reaction

1-(5-phosphoribosyl)-AMP + H₂O ${\displaystyle \rightleftharpoons }$ 1-(5-phosphoribosyl)-5-[(5- phosphoribosylamino)methylideneamino]imidazole-4-carboxamide

Thus, the two substrates of this enzyme are 1-(5-phosphoribosyl)-AMP and H₂O, whereas its two products are [[1-(5-phosphoribosyl)-5-[(5-]] and [[phosphoribosylamino)methylideneamino]imidazole-4-carboxamide]].

This enzyme belongs to the family of hydrolases, those acting on carbon-nitrogen bonds other than peptide bonds, specifically in cyclic amidines. The systematic name of this enzyme class is 1-(5-phospho-D-ribosyl)-AMP 1,6-hydrolase. Other names in common use include PRAMP-cyclohydrolase, and phosphoribosyladenosine monophosphate cyclohydrolase. This enzyme participates in histidine metabolism.

As of late 2007, only one structure has been solved for this class of enzymes, with the PDB accession code 1ZPS.

• Minson AC, Creaser EH (1969). "Purification of a trifunctional enzyme, catalysing three steps of the histidine pathway, from Neurospora crassa". Biochem. J. 114 (1): 49–56. doi:10.1042/bj1140049. PMC 1184794. PMID 4309307.