5-Methyltetrahydropteroyltriglutamate—homocysteine S-methyltransferase
| 5-methyltetrahydropteroyltriglutamate-homocysteine S-methyltransferase | |||||||||
|---|---|---|---|---|---|---|---|---|---|
| Identifiers | |||||||||
| EC number | 2.1.1.14 | ||||||||
| CAS number | 9068-29-5 | ||||||||
| Databases | |||||||||
| IntEnz | IntEnz view | ||||||||
| BRENDA | BRENDA entry | ||||||||
| ExPASy | NiceZyme view | ||||||||
| KEGG | KEGG entry | ||||||||
| MetaCyc | metabolic pathway | ||||||||
| PRIAM | profile | ||||||||
| PDB structures | RCSB PDB PDBe PDBsum | ||||||||
| Gene Ontology | AmiGO / EGO | ||||||||
| |||||||||
In enzymology, a 5-methyltetrahydropteroyltriglutamate—homocysteine S-methyltransferase (EC 2.1.1.14) is an enzyme that catalyzes the chemical reaction
- 5-methyltetrahydropteroyltri-L-glutamate + L-homocysteine tetrahydropteroyltri-L-glutamate + L-methionine
Thus, the two substrates of this enzyme are 5-methyltetrahydropteroyltri-L-glutamate and L-homocysteine, whereas its two products are tetrahydropteroyltri-L-glutamate 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 1T7L, 1U1H, 1U1J, 1U1U, 1U22, 1XDJ, 1XPG, 1XR2, and 2NQ5. The enzyme from Escherichia coli consists of two alpha8-beta8 (TIM) barrels positioned face to face and thought to have evolved by gene duplication.[1] The active site lies between the tops of the two barrels, the N-terminal barrel binds 5-methyltetrahydropteroyltri-L-glutamic acid and the C-terminal barrel binds homocysteine. Homocysteine is coordinated to a zinc ion, as initially suggested by spectroscopy and mutagenesis .
References
- ↑ Pejchal, Robert; Ludwig, Martha L. (2005). "Cobalamin-independent methionine synthase (MetE): a face-to-face double barrel that evolved by gene duplication". PLOS Biology. 3 (2). doi:10.1371/journal.pbio.0030031. PMC 539065
. PMID 15630480.
- Guest, JR; Friedman, S; Foster, MA; Tejerina, G; Woods, DD (Sep 1964). "Transfer of the methyl group from N5-methyltetrahydrofolates to homocysteine in Escherichia coli" (Free full text). Biochem. J. 92 (3): 497–504. ISSN 0264-6021. PMC 1206090. PMID 5319972.
- Whitfield, CD; Steers, Jr., EJ; Weisbach, H (Jan 1970). "Purification and properties of 5-methyltetrahydropteroyltriglutamate-homocysteine transmethylase" (Free full text). J. Biol. Chem. 245 (2): 390–401. ISSN 0021-9258. PMID 4904482.
- Eichel, J; Gonzalez, JC; Hotze, M; Matthews, RG; Schroder, J (Jun 1995). "Vitamin-B12-independent methionine synthase from a higher plant (Catharanthus roseus). Molecular characterization, regulation, heterologous expression, and enzyme properties" (Free full text). Eur. J. Biochem. 230 (3): 1053–8. doi:10.1111/j.1432-1033.1995.tb20655.x. ISSN 0014-2956. PMID 7601135.
- Gonzalez, JC; Peariso, K; Penner-Hahn, JE; Matthews, RG (Sep 1996). "Cobalamin-independent methionine synthase from Escherichia coli: a zinc metalloenzyme". Biochemistry. 35 (38): 12228–34. doi:10.1021/bi9615452. ISSN 0006-2960. PMID 8823155.
- Peariso, Katrina; Goulding, Celia W.; Huang, Sha; Matthews, Rowena G.; Penner-Hahn, James E. (1998). "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. doi:10.1021/ja980581g.