In enzymology, (S)-coclaurine-N-methyltransferase () is an enzyme that catalyzes the chemical reaction
S-adenosyl methionine (SAM) provides the methyl group for alkylation of (S)-coclaurine, which is converted to (S)-N-methylcoclaurine, with S-adenosylhomocysteine (SAH) as a by-product.
This enzyme belongs to the family of transferases, specifically those transferring one-carbon group methyltransferases. The systematic name of this enzyme class is S-adenosyl-L-methionine:(S)-coclaurine-N-methyltransferase. This enzyme participates in alkaloid biosynthesis.