N-methyltransferase with a substrate preference for (+-)-pavine, but also active with (R,S)-stylopine, (R,S)-scoulerine, (R,S)-tetrahydropalmatine, (R,S)-tetrahydropapaverine and (S)-reticuline (PubMed:19624470, PubMed:27573242). No activity with (R)-reticuline (PubMed:27573242). In the presence of a racemic mixture of tetrahydropapaverine (THP), one molecule of (S)-THP binds in a productive mode, while one molecule of (R)-THP is bound next to it in a non-productive mode (PubMed:27573242). The (R)-THP may inhibit the release of products from the enzyme when higher concentrations of the racemic substrate are added to the reaction (PubMed:27573242). (+-)-pavine + S-adenosyl-L-methionine = H(+) + N-methylpavine + S-adenosyl-L-homocysteine Homodimer. Not induced by elicitor treatment. Belongs to the CFA/CMAS family.