Biology: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 | ||||||||
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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 [math]\displaystyle{ \rightleftharpoons }[/math] 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
- ↑ "Cobalamin-independent methionine synthase (MetE): a face-to-face double barrel that evolved by gene duplication". PLOS Biology 3 (2): e31. February 2005. doi:10.1371/journal.pbio.0030031. PMID 15630480.
Further reading
- "Transfer of the methyl group from N5-methyltetrahydrofolates to homocysteine in Escherichia coli" (Free full text). The Biochemical Journal 92 (3): 497–504. September 1964. doi:10.1042/bj0920497. PMID 5319972.
- "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. June 1995. doi:10.1111/j.1432-1033.1995.tb20655.x. PMID 7601135. http://www3.interscience.wiley.com/resolve/openurl?genre=article&sid=nlm:pubmed&issn=0014-2956&date=1995&volume=230&issue=3&spage=1053.
- "Cobalamin-independent methionine synthase from Escherichia coli: a zinc metalloenzyme". Biochemistry 35 (38): 12228–34. September 1996. doi:10.1021/bi9615452. 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 (33): 8410–8416. doi:10.1021/ja980581g.
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