Glutaminyl-peptide cyclotransferase
In enzymology, a glutaminyl-peptide cyclotransferase (EC 2.3.2.5) is an enzyme that catalyzes the chemical reaction
- L-glutaminyl-peptide 5-oxoprolyl-peptide + NH3 or
- L-glutamyl-peptide 5-oxoprolyl-peptide + H2O
| glutaminyl-peptide cyclotransferase | |||||||||
|---|---|---|---|---|---|---|---|---|---|
| Identifiers | |||||||||
| EC number | 2.3.2.5 | ||||||||
| CAS number | 37257-21-9 | ||||||||
| 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 | ||||||||
| |||||||||
Hence, this enzyme has one substrate, L-glutaminyl-peptide or L-glutamyl-peptide, and two products, 5-oxoprolyl-peptide and NH3 or H2O. The N-terminal 5-oxoproline residue on the peptide is also commonly known as pyroglutamic acid.
This enzyme belongs to the family of transferases, specifically the aminoacyltransferases. The systematic name of this enzyme class is L-glutaminyl-peptide gamma-glutamyltransferase (cyclizing). Other names in common use include glutaminyl-tRNA cyclotransferase, glutaminyl cyclase, and glutaminyl-transfer ribonucleate cyclotransferase.
Structural studies
As of late 2007, 8 structures have been solved for this class of enzymes, with PDB accession codes 2AFM, 2AFO, 2AFS, 2AFU, 2AFW, 2AFX, 2AFZ, and 2IWA.
Human gene
QPCT - note that Q is one-letter abbreviation for glutamine, and glutaminyl is the name of the acyl group.
References
- Busby WH, Quackenbush GE, Humm J, Youngblood WW, Kizer JS (1987). "An enzyme(s) that converts glutaminyl-peptides into pyroglutamyl-peptides. Presence in pituitary, brain, adrenal medulla, and lymphocytes". J. Biol. Chem. 262 (18): 8532–6. PMID 3597387.
- Fischer WH, Spiess J (1987). "Identification of a mammalian glutaminyl cyclase converting glutaminyl into pyroglutamyl peptides". Proc. Natl. Acad. Sci. U.S.A. 84 (11): 3628–32. Bibcode:1987PNAS...84.3628F. doi:10.1073/pnas.84.11.3628. PMC 304928. PMID 3473473.
- Messer M; Ottesen M (1965). "Isolation and properties of glutamine cyclotransferase of dried papaya latex". C. R. Trav. Lab. Carlsberg. 35 (1): 1–24. PMID 5846578.