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 / QuickGO | ||||||||
| |||||||||
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 participates in methionine metabolism. It has 2 cofactors: orthophosphate, and zinc.
Nomenclature
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.
Structure
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 R, Ludwig ML (February 2005). "Cobalamin-independent methionine synthase (MetE): a face-to-face double barrel that evolved by gene duplication". PLoS Biology. 3 (2): e31. doi:10.1371/journal.pbio.0030031. PMC 539065. PMID 15630480.
Further reading
- Guest JR, Friedman S, Foster MA, Tejerina G, Woods DD (September 1964). "Transfer of the methyl group from N5-methyltetrahydrofolates to homocysteine in Escherichia coli" (Free full text). The Biochemical Journal. 92 (3): 497–504. PMC 1206090. PMID 5319972.
- Whitfield CD, Steers EJ, Weissbach H (January 1970). "Purification and properties of 5-methyltetrahydropteroyltriglutamate-homocysteine transmethylase" (Free full text). The Journal of Biological Chemistry. 245 (2): 390–401. PMID 4904482.
- Eichel J, González JC, Hotze M, Matthews RG, Schröder J (June 1995). "Vitamin-B12-independent methionine synthase from a higher plant (Catharanthus roseus). Molecular characterization, regulation, heterologous expression, and enzyme properties" (Free full text). European Journal of Biochemistry. 230 (3): 1053–8. doi:10.1111/j.1432-1033.1995.tb20655.x. PMID 7601135.
- González JC, Peariso K, Penner-Hahn JE, Matthews RG (September 1996). "Cobalamin-independent methionine synthase from Escherichia coli: a zinc metalloenzyme". Biochemistry. 35 (38): 12228–34. doi:10.1021/bi9615452. PMID 8823155.
- Peariso K, Goulding CW, Huang S, Matthews RG, Penner-Hahn JE (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&ndash, 8416. doi:10.1021/ja980581g.