5-methyltetrahydropteroyltriglutamate-homocysteine S-methyltransferase

In enzymology, a 5-methyltetrahydropteroyltriglutamate-homocysteine S-methyltransferase is an enzyme that catalyzes the chemical reaction

5-methyltetrahydropteroyltri-L-glutamate + L-homocysteine rightleftharpoons tetrahydropteroyltri-L-glutamate + L-methionine

Thus, the two substrates of this enzyme are 5-methyltetrahydropteroyltri-L-glutamatic acid and L-homocysteine, whereas its two products are tetrahydropteroyltri-L-glutamatic acid and L-methionine.

This enzyme belongs to the family of transferases, specifically those transferring one-carbon group methyltransferases. The systematic name of this enzyme class is 5-methyltetrahydropteroyltri-L-glutamate:L-homocysteine S-methyltransferase. Other names in common use include tetrahydropteroyltriglutamate methyltransferase, homocysteine methylase, methyltransferase, tetrahydropteroylglutamate-homocysteine transmethylase, methyltetrahydropteroylpolyglutamate:homocysteine methyltransferase, cobalamin-independent methionine synthase, methionine synthase (cobalamin-independent), and MetE. This enzyme participates in methionine metabolism. It has 2 cofactors: orthophosphate, and zinc.

Structural studies

As of late 2007, 9 structures have been solved for this class of enzymes, with PDB accession codes , , , , , , , , and .


  • Guest JR, Friedman S, Foster MA, Tejerina G, Woods DD "Transfer of the methyl group from N5-methyltetrahydrofolates to homocysteine in Escherichia coli". Biochem. J. 92 497–504.
  • Whitfield CD, Steers EJ Jr, Weisbach H "Purification and properties of 5-methyltetrahydropteroyltriglutamate-homocysteine transmethylase". J. Biol. Chem. 245 390–401.
  • Eichel J, Gonzalez JC, Hotze M, Matthews RG, 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 1053–8.
  • Gonzalez JC, Peariso K, Penner-Hahn JE, Matthews RG "Cobalamin-independent methionine synthase from Escherichia coli: a zinc metalloenzyme". Biochemistry. 35 12228–34.
  • Penner-Hahn JE "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 8410–8416.

External links

The CAS registry number for this enzyme class is .

Gene Ontology (GO) codes

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