IMP cyclohydrolase
| IMP cyclohydrolase | |||||||||
|---|---|---|---|---|---|---|---|---|---|
| Identifiers | |||||||||
| EC no. | 3.5.4.10 | ||||||||
| CAS no. | 9013-81-4 | ||||||||
| 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 | ||||||||
| |||||||||
| IMP cyclohydrolase-like protein | |||||||
|---|---|---|---|---|---|---|---|
 crystal structure of puro from methanothermobacter thermoautotrophicus | |||||||
| Identifiers | |||||||
| Symbol | IMP_cyclohyd | ||||||
| Pfam | PF07826 | ||||||
| InterPro | IPR020600 | ||||||
| |||||||
In enzymology, an IMP cyclohydrolase (EC 3.5.4.10) is an enzyme that catalyzes the chemical reaction
- IMP + H2O 5-formamido-1-(5-phospho-D-ribosyl)imidazole-4-carboxamide
Thus, the two substrates of this enzyme are IMP and H2O, whereas its product is 5-formamido-1-(5-phospho-D-ribosyl)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 IMP 1,2-hydrolase (decyclizing). Other names in common use include inosinicase, and inosinate cyclohydrolase. This enzyme catalyses the cyclisation of 5-formylamidoimidazole-4-carboxamide ribonucleotide to IMP, a reaction which is important in de novo purine biosynthesis in archaeal species.[1]
Structural studies
[edit]In most cases this single-domain protein is arranged to form an overall fold that consists of a four-layered alpha-beta-beta-alpha core structure. The two antiparallel beta-sheets pack against each other and are covered by alpha-helices on one face of the molecule. The protein is structurally similar to members of the N-terminal nucleophile (NTN) hydrolase superfamily. A deep pocket was in fact found on the surface of IMP cyclohydrolase in a position equivalent to that of active sites of NTN-hydrolases, but an N-terminal nucleophile could not be found. Therefore, it is thought that this enzyme is structurally but not functionally similar to members of the NTN-hydrolase family.[2]
As of late 2007, 14 structures have been solved for this class of enzymes, with PDB accession codes PDB: 1G8M, PDB: 1M9N, PDB: 1OZ0, PDB: 1P4R, PDB: 1PKX, PDB: 1PL0, PDB: 1THZ, PDB: 2B1G, PDB: 2B1I, PDB: 2IU0, PDB: 2IU3, PDB: 2NTK, PDB: 2NTL, and PDB: 2NTM.
References
[edit]- ^ Graupner M, Xu H, White RH (March 2002). "New class of IMP cyclohydrolases in Methanococcus jannaschii". J. Bacteriol. 184 (5): 1471–3. doi:10.1128/jb.184.5.1471-1473.2002. PMC 134845. PMID 11844782.
- ^ Saridakis V, Christendat D, Thygesen A, Arrowsmith CH, Edwards AM, Pai EF (July 2002). "Crystal structure of Methanobacterium thermoautotrophicum conserved protein MTH1020 reveals an NTN-hydrolase fold". Proteins. 48 (1): 141–3. doi:10.1002/prot.10147. PMID 12012346. S2CID 29556936.
Further reading
[edit]- FLAKS JG, ERWIN MJ, BUCHANAN JM (1957). "Biosynthesis of the purines. XVIII 5-Amino-1-ribosyl-4-imidazolecarboxamide 5'-phosphate transformylase and inosinicase". J. Biol. Chem. 229 (2): 603–12. doi:10.1016/S0021-9258(19)63668-9. PMID 13502325.
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