Quercetin 3-O-methyltransferase

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In enzymology, a quercetin 3-O-methyltransferase (EC 2.1.1.76) is an enzyme that catalyzes the chemical reaction

S-adenosyl-L-methionine + 3,5,7,3',4'-pentahydroxyflavone $\rightleftharpoons$ S-adenosyl-L-homocysteine + 3-methoxy-5,7,3',4'-tetrahydroxyflavone

Thus, the two substrates of this enzyme are S-adenosyl methionine and 3,5,7,3',4'-pentahydroxyflavone, whereas its two products are S-adenosylhomocysteine and 3-methoxy-5,7,3',4'-tetrahydroxyflavone.

This enzyme belongs to the family of transferases, specifically those transferring one-carbon group methyltransferases. The systematic name of this enzyme class is S-adenosyl-L-methionine:3,5,7,3',4'-pentahydroxyflavone 3-O-methyltransferase. Other names in common use include flavonol 3-O-methyltransferase, and flavonoid 3-methyltransferase. This enzyme participates in flavonoid biosynthesis.

[edit] References

IUBMB entry for 2.1.1.76
BRENDA references for 2.1.1.76 (Recommended.)
PubMed references for 2.1.1.76
PubMed Central references for 2.1.1.76
Google Scholar references for 2.1.1.76
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De Luca V, Ibrahim RK (1985). "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: 606–18. doi:10.1016/0003-9861(85)90206-1. PMID 3994394.
Ibrahim RK and De Luca V (1982). "Polymethylated flavonol synthesis is catalyzed by distinct O-methyltransferases". Naturwissenschaften 69: 41–42. doi:10.1007/BF00441101.