Reaction: S-adenosyl-L-methionine + 5,6,3',4'-tetrahydroxy-3,7-dimethoxyflavone = S-adenosyl-L-homocysteine + 5,3',4'-trihydroxy-3,6,7-trimethoxyflavone
Other name(s): flavonol 6-O-methyltransferase; flavonol 6-methyltransferase; 6-OMT; S-adenosyl-L-methionine:3',4',5,6-tetrahydroxy-3,7-dimethoxyflavone 6-O-methyltransferase
Systematic name: S-adenosyl-L-methionine:5,6,3',4'-tetrahydroxy-3,7-dimethoxyflavone 6-O-methyltransferase
Comments: The enzymes from Chrysosplenium americanum also methylates 3,7,3'-trimethylquercetagetin at the 6-position. Does not act on flavones, dihydroflavonols, or their glucosides.
Links to other databases: BRENDA, EXPASY, KEGG, Metacyc, CAS registry number: 97089-68-4
References:
1. De Luca, V. and Ibrahim, R.K. Enzymatic synthesis of polymethylated flavonols in Chrysosplenium americanum. I. Partial purification and some properties of S-adenosyl-L-methionine:flavonol 3-, 6-, 7-, and 4'-O-methyltransferases. Arch. Biochem. Biophys. 238 (1985) 596-605. [PMID: 3994393]
2. De Luca, V. and Ibrahim, R.K. Enzymatic synthesis of polymethylated flavonols in Chrysosplenium americanum. II. Substrate interaction and product inhibition studies of flavonol 3-, 6-, and 4'-O-methyltransferases. Arch. Biochem. Biophys. 238 (1985) 606-618. [PMID: 3994394]