EC - Homocysteine S-methyltransferase

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IntEnz Enzyme Nomenclature


Accepted name:
homocysteine S-methyltransferase
Other names:
S-adenosyl-L-methionine:L-homocysteine methyltransferase
S-adenosylmethionine homocysteine transmethylase
S-adenosylmethionine-homocysteine transmethylase
S-adenosylmethionine:homocysteine methyltransferase
S-methylmethionine homocysteine transmethylase
L-homocysteine S-methyltransferase
adenosylmethionine transmethylase
adenosylmethionine:homocysteine methyltransferase
homocysteine methylase
homocysteine methyltransferase
homocysteine transmethylase
methylmethionine:homocysteine methyltransferase
Systematic name:
S-adenosyl-L-methionine:L-homocysteine S-methyltransferase



The enzyme uses S-adenosyl-L-methionine as methyl donor less actively than S-methyl-L-methionine.

Links to other databases

Enzymes and pathways: NC-IUBMB , BRENDA , ExplorEnz , ENZYME@ExPASy , KEGG , MetaCyc , NIST 74 , UniPathway
Structural data: CSA , EC2PDB
CAS Registry Number: 9012-40-2
UniProtKB/Swiss-Prot: (17) [show] [UniProt]


  1. Balish, E. and Shapiro, S.K.
    Methionine biosynthesis in Escherichia coli: induction and repression of methylmethionine (or adenosylmethionine):homocysteine methyltransferase.
    Arch. Biochem. Biophys. 119: 62-68 (1967). [PMID: 4861151]
  2. Shapiro, S.K.
    Adenosylmethionine-homocysteine transmethylase.
    Biochim. Biophys. Acta 29: 405-409 (1958). [PMID: 13572358]
  3. Shapiro, S.K. and Yphantis, D.A.
    Assay of S-methylmethionine and S-adenosylmethionine homocysteine transmethylases.
    Biochim. Biophys. Acta 36: 241-244 (1959). [PMID: 14445542]
  4. Mudd, S. H., Datko, A. H.
    The S-Methylmethionine Cycle in Lemna paucicostata.
    Plant Physiol. 93: 623-630 (1990). [PMID: 16667513]
  5. Ranocha, P., McNeil, S. D., Ziemak, M. J., Li, C., Tarczynski, M. C., Hanson, A. D.
    The S-methylmethionine cycle in angiosperms: ubiquity, antiquity and activity.
    Plant J. 25: 575-584 (2001). [PMID: 11309147]
  6. Ranocha, P., Bourgis, F., Ziemak, M. J., Rhodes, D., Gage, D. A., Hanson, A. D.
    Characterization and functional expression of cDNAs encoding methionine-sensitive and -insensitive homocysteine S-methyltransferases from Arabidopsis.
    J. Biol. Chem. 275: 15962-15968 (2000). [PMID: 10747987]
  7. Grue-Sørensen, G., Kelstrup, E., Kjær, A. and Madsen, J.Ø.
    Diastereospecific, enzymically catalysed transmethylation from S-methyl-L-methionine to L-homocysteine, a naturally occurring process.
    J. Chem. Soc. Perkin Trans. 1 1091-1097 (1984).

[EC created 1965, modified 2010]