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