(1) S-adenosyl-L-methionine + a 3'-hydroxyflavonoid = S-adenosyl-L-homocysteine + a 3'-methoxyflavonoid;
(2) S-adenosyl-L-methionine + a 5'-hydroxy-3'-methoxyflavonoid = S-adenosyl-L-homocysteine + a 3',5'-dimethoxyflavonoid
Isolated from Vitis vinifera (grape) [2]. Most active with delphinidin 3-glucoside but also acts on cyanidin 3-glucoside, cyanidin, myricetin, quercetin and quercetin 3-glucoside. The enzyme from Catharanthus roseus was most active with myricetin [1].
