3-O-acetyl-4'-O-demethylpapaveroxine + (S)-S-adenosyl-L-methionine <=> 3-O-acetylpapaveroxine + S-adenosyl-L-homocysteine + H(+)
3-o-acetyl-4'-o-demethylpapaveroxine + (s)-s-adenosyl-l-methionine <=> 3-o-acetylpapaveroxine + s-adenosyl-l-homocysteine + h(+)