Reaction: α-(γ-L-glutamyl)-L-amino acid = α-L-amino acid + 5-oxo-L-proline
Other name(s): γ-glutamyl-amino acid cyclotransferase; γ-L-glutamylcyclotransferase; L-glutamic cyclase; (5-L-glutamyl)-L-amino-acid 5-glutamyltransferase (cyclizing); GGCT
Systematic name: α-(γ-L-glutamyl)-L-amino-acid γ-glutamyl cyclotransferase (5-oxo-L-proline producing)
Comments: The enzyme, found in animals and plants, acts on derivatives of L-glutamate, L-2-aminobutanoate, L-alanine and glycine. The enzyme acts as a cyclotransferase, cleaving the amide bond via transamidation using the α-amine of the L-glutamyl residue, releasing it as the cyclic 5-oxo-L-proline.
Links to other databases: BRENDA, EXPASY, KEGG, MetaCyc, CAS registry number:
1. Bodnaryk, R.P. and McGirr, L. Purification, properties and function of a unique γ-glutamyl cyclotransferase from the housefly, Musca domestica L. Biochim. Biophys. Acta 315 (1973) 352-362.
2. Orlowski, M., Richman, P.G. and Meister, A. Isolation and properties of γ-L-glutamylcyclotransferase from human brain. Biochemistry 8 (1969) 1048-1055. [PMID: 5781001]
3. Oakley, A.J., Yamada, T., Liu, D., Coggan, M., Clark, A.G. and Board, P.G. The identification and structural characterization of C7orf24 as γ-glutamyl cyclotransferase. An essential enzyme in the γ-glutamyl cycle. J. Biol. Chem. 283 (2008) 22031-22042. [PMID: 18515354]
4. Paulose, B., Chhikara, S., Coomey, J., Jung, H.I., Vatamaniuk, O. and Dhankher, O.P. A γ-glutamyl cyclotransferase protects Arabidopsis plants from heavy metal toxicity by recycling glutamate to maintain glutathione homeostasis. Plant Cell 25 (2013) 4580-4595. [PMID: 24214398]