“IMP cyclohydrolase”的意思、由来-开放百科全书

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IMP cyclohydrolase

释义

Structural studies
References
Further reading

{{enzyme
| Name = IMP cyclohydrolase
| EC_number = 3.5.4.10
| CAS_number = 9013-81-4
| IUBMB_EC_number = 3/5/4/10
| GO_code = 0003937
| image =
| width =
| caption =
}}{{Infobox protein family
| Symbol = IMP_cyclohyd
| Name = IMP cyclohydrolase-like protein
| image = PDB 2ntm EBI.jpg
| width =
| caption = crystal structure of puro from methanothermobacter thermoautotrophicus
| Pfam = PF07826
| Pfam_clan =
| InterPro = IPR020600
| SMART =
| PROSITE =
| MEROPS =
| SCOP =
| TCDB =
| OPM family =
| OPM protein =
| CAZy =
| CDD =
}}

In enzymology, an IMP cyclohydrolase ({{EC number|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

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 link|1G8M}}, {{PDB link|1M9N}}, {{PDB link|1OZ0}}, {{PDB link|1P4R}}, {{PDB link|1PKX}}, {{PDB link|1PL0}}, {{PDB link|1THZ}}, {{PDB link|2B1G}}, {{PDB link|2B1I}}, {{PDB link|2IU0}}, {{PDB link|2IU3}}, {{PDB link|2NTK}}, {{PDB link|2NTL}}, and {{PDB link|2NTM}}.

References

1. ^{{cite journal | vauthors = Graupner M, Xu H, White RH | title = New class of IMP cyclohydrolases in Methanococcus jannaschii | journal = J. Bacteriol. | volume = 184 | issue = 5 | pages = 1471–3 |date=March 2002 | pmid = 11844782 | pmc = 134845 | doi = 10.1128/jb.184.5.1471-1473.2002| url = }}
2. ^{{cite journal | vauthors = Saridakis V, Christendat D, Thygesen A, Arrowsmith CH, Edwards AM, Pai EF | title = Crystal structure of Methanobacterium thermoautotrophicum conserved protein MTH1020 reveals an NTN-hydrolase fold | journal = Proteins | volume = 48 | issue = 1 | pages = 141–3 |date=July 2002 | pmid = 12012346 | doi = 10.1002/prot.10147 | url = }}

Structural studies

References

Further reading