In enzymology, an apigenin 4'-O-methyltransferase () is an

enzyme Enzymes () are proteins that act as biological catalysts by accelerating chemical reactions. The molecules upon which enzymes may act are called substrate (chemistry), substrates, and the enzyme converts the substrates into different molecule ...

that

catalyzes Catalysis () is the process of increasing the rate of a chemical reaction by adding a substance known as a catalyst (). Catalysts are not consumed in the reaction and remain unchanged after it. If the reaction is rapid and the catalyst recyc ...

the

chemical reaction A chemical reaction is a process that leads to the chemical transformation of one set of chemical substances to another. Classically, chemical reactions encompass changes that only involve the positions of electrons in the forming and break ...

:S-adenosyl-L-methionine + 5,7,4'-trihydroxyflavone

\rightleftharpoons

S-adenosyl-L-homocysteine + 4'-methoxy-5,7-dihydroxyflavone Thus, the two substrates of this enzyme are

S-adenosyl methionine ''S''-Adenosyl methionine (SAM), also known under the commercial names of SAMe, SAM-e, or AdoMet, is a common cosubstrate involved in methyl group transfers, transsulfuration, and aminopropylation. Although these anabolic reactions occur throug ...

and 5,7,4'-trihydroxyflavone (apigenin), whereas its two products are S-adenosylhomocysteine and

4'-methoxy-5,7-dihydroxyflavone Acacetin is a 4′- ''O''-methylated flavone of the parent compound apigenin, found in ''Robinia pseudoacacia'' (black locust), ''Turnera diffusa'' (damiana), shows moderate aromatase inhibition, '' Betula pendula'' (silver birch), and in the fe ...

(acacetin). This enzyme belongs to the family of

transferase A transferase is any one of a class of enzymes that catalyse the transfer of specific functional groups (e.g. a methyl or glycosyl group) from one molecule (called the donor) to another (called the acceptor). They are involved in hundreds of ...

s, specifically those transferring one-carbon group methyltransferases. The

systematic name A systematic name is a name given in a systematic way to one unique group, organism, object or chemical substance, out of a specific population or collection. Systematic names are usually part of a nomenclature. A semisystematic name or semitrivial ...

of this enzyme class is S-adenosyl-L-methionine:5,7,4'-trihydroxyflavone 4'-O-methyltransferase. Other names in common use include flavonoid O-methyltransferase, and flavonoid methyltransferase. This enzyme participates in

flavonoid biosynthesis Flavonoids are synthesized by the phenylpropanoid metabolic pathway in which the amino acid phenylalanine is used to produce 4-coumaroyl-CoA. This can be combined with malonyl-CoA to yield the true backbone of flavonoids, a group of compounds cal ...

References

* EC 2.1.1 Enzymes of unknown structure O-methylated flavones metabolism {{2.1-enzyme-stub