kaempferide + S-adenosyl-L-methionine = 3,4'-O-dimethylkaempferol + S-adenosyl-L-homocysteine + H(+)
kaempferide + s-adenosyl-l-methionine = 3,4'-o-dimethylkaempferol + s-adenosyl-l-homocysteine + h(+)