IUBMB Enzyme Nomenclature


Accepted name: glutaminyl-peptide cyclotransferase

Reaction: L-glutaminyl-peptide = 5-oxoprolyl-peptide + NH3

Other name(s): glutaminyl-tRNA cyclotransferase; glutaminyl cyclase; glutaminyl-transfer ribonucleate cyclotransferase

Systematic name: L-glutaminyl-peptide γ-glutamyltransferase (cyclizing)

Comments: 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: BRENDA, EXPASY, KEGG, Metacyc, PDB, CAS registry number: 37257-21-9


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 (1987) 8532-8536. [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 (1987) 3628-3632. [PMID: 3473473]

3. Messer, M. and Ottesen, M. Isolation and properties of glutamine cyclotransferase of dried papaya latex. C.R. Trav. Lab. Carlsberg 35 (1965) 1-24.

[EC created 1972, modified 1990]

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