EC - Glutaminyl-peptide cyclotransferase

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IntEnz Enzyme Nomenclature


Accepted name:
glutaminyl-peptide cyclotransferase
Other names:
glutaminyl cyclase
glutaminyl-tRNA cyclotransferase
glutaminyl-transfer ribonucleate cyclotransferase
Systematic name:
L-glutaminyl-peptide γ-glutamyltransferase (cyclizing)



Involved in the formation of thyrotropin-releasing hormone and other biologically active peptides containing N-terminal pyroglutamyl residues. The enzyme from papaya also acts on glutaminyl-tRNA.

Links to other databases

Enzymes and pathways: NC-IUBMB , BRENDA , ExplorEnz , ENZYME@ExPASy , KEGG , MetaCyc , UniPathway
Structural data: CSA , EC2PDB
Gene Ontology: GO:0016603
CAS Registry Number: 37257-21-9
UniProtKB/Swiss-Prot: (21) [show] [UniProt]


  1. Busby, W.H., Quackenbush, G.E., Humm, J., Youngblood, W.W. and Kizer, J.S.
    An enzyme(s) that converts glutaminyl-peptides into pyroglutamyl-peptides. Presence in pituitary, brain, adrenal medulla, and lymphocytes.
    J. Biol. Chem. 262 : 8532-8536 (1987). [PMID: 3597387]
  2. Fischer, W.H. and Spiess, J.
    Identification of a mammalian glutaminyl cyclase converting glutaminyl into pyroglutamyl peptides.
    Proc. Natl. Acad. Sci. USA 84 : 3628-3632 (1987). [PMID: 3473473]
  3. Messer, M. and Ottesen, M.
    Isolation and properties of glutamine cyclotransferase of dried papaya latex.
    C.R. Trav. Lab. Carlsberg 35 : 1-24 (1965).

[EC created 1972, modified 1990]