KEGG   ENZYME: 2.1.1.76Help
Entry
EC 2.1.1.76                 Enzyme                                 

Name
quercetin 3-O-methyltransferase;
flavonol 3-O-methyltransferase;
flavonoid 3-methyltransferase
Class
Transferases;
Transferring one-carbon groups;
Methyltransferases
BRITE hierarchy
Sysname
S-adenosyl-L-methionine:3,5,7,3',4'-pentahydroxyflavone 3-O-methyltransferase
Reaction(IUBMB)
S-adenosyl-L-methionine + 3,5,7,3',4'-pentahydroxyflavone = S-adenosyl-L-homocysteine + 3-methoxy-5,7,3',4'-tetrahydroxyflavone [RN:R02157]
Reaction(KEGG)
R02157;
(other) R05035
Show
Substrate
S-adenosyl-L-methionine [CPD:C00019];
3,5,7,3',4'-pentahydroxyflavone [CPD:C00389]
Product
S-adenosyl-L-homocysteine [CPD:C00021];
3-methoxy-5,7,3',4'-tetrahydroxyflavone [CPD:C04443]
Comment
Specific for quercetin. Related enzymes bring about the 3-O-methylation of other flavonols, such as galangin and kaempferol.
History
EC 2.1.1.76 created 1984
Pathway
ec00944  Flavone and flavonol biosynthesis
Orthology
K05279  flavonol 3-O-methyltransferase
Reference
1
  Authors
De Luca, V., Brunet, G., Khouri, H., Ibrahim, R. and Hrazdina, G.
  Title
Flavonol 3-O-methyltransferase in plant-tissues.
  Journal
Z Naturforsch 37:134-135 (1982)
Reference
2  [PMID:3994393]
  Authors
De Luca V, Ibrahim RK.
  Title
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.
  Journal
Arch Biochem Biophys 238:596-605 (1985)
DOI:10.1016/0003-9861(85)90205-X
Reference
3  [PMID:3994394]
  Authors
De Luca V, Ibrahim RK.
  Title
Enzymatic synthesis of polymethylated flavonols in Chrysosplenium americanum. II. Substrate interaction and product inhibition studies of flavonol 3-, 6-, and 4'-O-methyltransferases.
  Journal
Arch Biochem Biophys 238:606-18 (1985)
DOI:10.1016/0003-9861(85)90206-1
Reference
4
  Authors
Ibrahim, R.K. and De Luca, V.
  Title
Polymethylated flavonol synthesis is catalyzed by distinct O-methyltransferases.
  Journal
Naturwissenschaften 69:41-42 (1982)
Other DBs
ExplorEnz - The Enzyme Database: 2.1.1.76
IUBMB Enzyme Nomenclature: 2.1.1.76
ExPASy - ENZYME nomenclature database: 2.1.1.76
BRENDA, the Enzyme Database: 2.1.1.76
CAS: 81295-55-8

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