(S)-tetrahydrocolumbamine + S-adenosyl-L-methionine => (S)-tetrahydropalmatine + S-adenosyl-L-homocysteine + H(+)
(s)-tetrahydrocolumbamine + s-adenosyl-l-methionine => (s)-tetrahydropalmatine + s-adenosyl-l-homocysteine + h(+)