Reaction: tetrahydropteroyl-(γ-glutamyl)n + (n-1) H2O = 5,6,7,8-tetrahydrofolate + (n-1) L-glutamate
For diagram of reaction click here.
Other name(s): GGH (gene name) conjugase; folate conjugase; lysosomal γ-glutamyl carboxypeptidase; γ-Glu-X carboxypeptidase; pteroyl-poly-γ-glutamate hydrolase; carboxypeptidase G; folic acid conjugase; poly(γ-glutamic acid) endohydrolase; polyglutamate hydrolase; poly(glutamic acid) hydrolase II; pteroylpoly-γ-glutamyl hydrolase; γ-glutamyl hydrolase
Systematic name: tetrahydropteroyl-poly-γ-glutamyl γ-glutamyl hydrolase
Comments: The enzyme, which occurs only in animals and plants, can be either endo- and/or exopeptidase. It acts on tetrahydropteroyl polyglutamates and their modified forms, as well as the polyglutamates of the folate breakdown product N-(4-aminobenzoyl)-L-glutamate (pABA-Glu). The initial cleavage may release either monoglutamate or poly-γ-glutamate of two or more residues, depending on the specific enzyme. For example, GGH1 from the plant Arabidopsis thaliana cleaves pentaglutamates, mainly to di- and triglutamates, whereas GGH2 from the same organism yields mainly monoglutamates. The enzyme is lysosomal (and secreted) in animals and vacuolar in plants.
Links to other databases: BRENDA, EXPASY, ExplorEnz, GTD, KEGG, MetaCyc, MEROPS, PDB, CAS registry number: 9074-87-7
References:
1. McGuire, J.J. and Coward, J.K. Pteroylpolyglutamates: biosynthesis, degradation and function.. In: Blakley, R.L. and Benkovic, S.J. (Eds), Folates and Pterins, John Wiley and Sons, New York, 1984, pp. 135-191.
2. Wang, Y., Nimec, Z., Ryan, T.J., Dias, J.A. and Galivan, J. The properties of the secreted γ-glutamyl hydrolases from H35 hepatoma cells. Biochim. Biophys. Acta 1164 (1993) 227-235. [PMID: 8343522]
3. Yao, R., Rhee, M.S. and Galivan, J. Effects of γ-glutamyl hydrolase on folyl and antifolylpolyglutamates in cultured H35 hepatoma cells. Mol. Pharmacol. 48 (1995) 505-511. [PMID: 7565632]
4. Yao, R., Schneider, E., Ryan, T.J. and Galivan, J. Human γ-glutamyl hydrolase: cloning and characterization of the enzyme expressed in vitro. Proc. Natl. Acad. Sci. USA 93 (1996) 10134-10138. [PMID: 8816764]
5. Yao, R., Nimec, Z., Ryan, T.J. and Galivan, J. Identification, cloning, and sequencing of a cDNA coding for rat γ-glutamyl hydrolase. J. Biol. Chem. 271 (1996) 8525-8528. [PMID: 8621474]
6. Orsomando, G., de la Garza, R.D., Green, B.J., Peng, M., Rea, P.A., Ryan, T.J., Gregory, J.F., 3rd and Hanson, A.D. Plant γ-glutamyl hydrolases and folate polyglutamates: characterization, compartmentation, and co-occurrence in vacuoles. J. Biol. Chem. 280 (2005) 28877-28884. [PMID: 15961386]
7. Akhtar, T.A., McQuinn, R.P., Naponelli, V., Gregory, J.F., 3rd, Giovannoni, J.J. and Hanson, A.D. Tomato γ-glutamylhydrolases: expression, characterization, and evidence for heterodimer formation. Plant Physiol. 148 (2008) 775-785. [PMID: 18757550]