The Enzyme Database

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Accepted name: isoflavone 7-O-methyltransferase
Reaction: S-adenosyl-L-methionine + a 7-hydroxyisoflavone = S-adenosyl-L-homocysteine + a 7-methoxyisoflavone
For diagram of the biosynthesis of formononetin and derivatives, click here and of biochanin A, click here
Systematic name: S-adenosyl-L-methionine:hydroxyisoflavone 7-O-methyltransferase
Comments: The enzyme from alfalfa can methylate daidzein, genistein and 6,7,4′-trihydroxyisoflavone but not flavones or flavanones.
Links to other databases: BRENDA, EXPASY, KEGG, MetaCyc, PDB, CAS registry number: 136111-54-1
1.  Edwards, R. and Dixon, R.A. Isoflavone O-methyltransferase activities in elicitor-treated cell suspension cultures of Medicago sativa. Phytochemistry 30 (1991) 2597–2606.
2.  He, X.Z. and Dixon, R.A. Genetic manipulation of isoflavone 7-O-methyltransferase enhances biosynthesis of 4′-O-methylated isoflavonoid phytoalexins and disease resistance in alfalfa. Plant Cell 12 (2000) 1689–1702. [PMID: 11006341]
3.  He, X.-Z. and Dixon, R.A. Affinity chromatography, substrate/product specificity, and amino acid sequence analysis of an isoflavone O-methyltransferase from alfalfa (Medicago sativa L.). Arch. Biochem. Biophys. 336 (1996) 121–129. [PMID: 8951042]
4.  He, X.Z., Reddy, J.T. and Dixon, R.A. Stress responses in alfalfa (Medicago sativa L). XXII. cDNA cloning and characterization of an elicitor-inducible isoflavone 7-O-methyltransferase. Plant Mol. Biol. 36 (1998) 43–54. [PMID: 9484461]
5.  Liu, C.-J. and Dixon, R.A. Elicitor-induced association of isoflavone O-methyltransferase with endomembranes prevents the formation and 7-O-methylation of daidzein during isoflavonoid phytoalexin biosynthesis. Plant Cell 13 (2001) 2643–2658. [PMID: 11752378]
6.  Zubieta, C., He, X.-Z., Dixon, R.A. and Noel, J.P. Structures of two natural product methyltransferases reveal the basis for substrate specificity in plant O-methyltransferases. Nat. Struct. Biol. 8 (2001) 271–279. [PMID: 11224575]
[EC created 2003]

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