IUBMB Enzyme Nomenclature


Accepted name: 5-methyltetrahydropteroyltriglutamate—homocysteine S-methyltransferase

Reaction: 5-methyltetrahydropteroyltri-L-glutamate + L-homocysteine = tetrahydropteroyltri-L-glutamate + L-methionine

For diagram of reaction click here.

Other name(s): tetrahydropteroyltriglutamate methyltransferase; homocysteine methylase; methyltransferase, tetrahydropteroylglutamate-homocysteine transmethylase; methyltetrahydropteroylpolyglutamate:homocysteine methyltransferase; cobalamin-independent methionine synthase; methionine synthase (cobalamin-independent); MetE

Systematic name: 5-methyltetrahydropteroyltri-L-glutamate:L-homocysteine S-methyltransferase

Comments: Requires phosphate and contains zinc. The enzyme from Escherichia coli also requires a reducing system. Unlike EC, methionine synthase, this enzyme does not contain cobalamin.

Links to other databases: BRENDA, EXPASY, KEGG, Metacyc, PDB, CAS registry number: 9068-29-5


1. Guest, J.R., Friedman, S., Foster, M.A., Tejerina, G. and Woods, D.D. Transfer of the methy grouup from N5-methyltetrahydrofolates to homocysteine in Escherichia coli. Biochem. J. 92 (1964) 497-504.

2. Whitfield, C.D., Steers, E.J., Jr. and Weissbach, H. Purification and properties of 5-methyltetrahydropteroyltriglutamate-homocysteine transmethylase. J. Biol. Chem. 245 (1970) 390-401. [PMID: 4904482]

3. Eichel, J., Gonzalez, J.C., Hotze, M., Matthews, R.G. and Schroder, J. Vitamin B12-independent methionine synthase from a higher-plant (Catharanthus roseus) - molecular characterization, regulation, heterologous expression, and enzyme properties. Eur. J. Biochem. 230 (1995) 1053-1058. [PMID: 7601135]

4. Gonzalez, J.C., Peariso, K., PennerHahn, J.E. and Matthews, R.G. Cobalamin-independent methionine synthase from Escherichia coli: A zinc metalloenzyme. Biochemistry 35 (1996) 12228-12234. [PMID: 8823155]

5. Peariso, K., Goulding, C.W., Huang, S., Matthews, R.G. and Penner-Hahn, J.E. Characterization of the zinc binding site in methionine synthase enzymes of Escherichia coli: The role of zinc in the methylation of homocysteine. J. Am. Chem. Soc. 120 (1998) 8410-8416.

[EC created 1972, modified 2003]

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