3,3'-O-dimethylquercetin + S-adenosyl-L-homocysteine + H(+) => 3',4',5,7-tetrahydroxy-3-methoxyflavone + S-adenosyl-L-methionine
3,3'-o-dimethylquercetin + s-adenosyl-l-homocysteine + h(+) => 3',4',5,7-tetrahydroxy-3-methoxyflavone + s-adenosyl-l-methionine