EC 2.1.1.155     
Accepted name: kaempferol 4′-O-methyltransferase
Reaction: S-adenosyl-L-methionine + kaempferol = S-adenosyl-L-homocysteine + kaempferide
Glossary: kaempferide = 3,5,7-trihydroxy-4′-methoxyflavone
Other name(s): S-adenosyl-L-methionine:flavonoid 4′-O-methyltransferase; F 4′-OMT
Systematic name: S-adenosyl-L-methionine:kaempferol 4′-O-methyltransferase
Comments: The enzyme acts on the hydroxy group in the 4′-position of some flavones, flavanones and isoflavones. Kaempferol, apigenin and kaempferol triglucoside are substrates, as is genistein, which reacts more slowly. Compounds with an hydroxy group in the 3′ and 4′ positions, such as quercetin and eriodictyol, do not act as substrates. Similar to EC 2.1.1.75, apigenin 4′-O-methyltransferase and EC 2.1.1.83, 3,7-dimethylquercetin 4′-O-methyltransferase.
References:
1.  Curir, P., Lanzotti, V., Dolci, M., Dolci, P., Pasini, C. and Tollin, G. Purification and properties of a new S-adenosyl-L-methionine:flavonoid 4′-O-methyltransferase from carnation (Dianthus caryophyllus L.). Eur. J. Biochem. 270 (2003) 3422–3431. [PMID: 12899699]
[EC 2.1.1.155 created 2004]