In enzymology, a N-methylcoclaurine 3'-monooxygenase () is an enzyme that catalyzes the chemical reaction
The 4 substrates of this enzyme are (S)-N-methylcoclaurine, NADPH, H<sup>+</sup>, and O<sub>2</sub>, whereas its 3 products are (S)-3'-hydroxy-N-methylcoclaurine, NADP<sup>+</sup>, and H<sub>2</sub>O.
This enzyme belongs to the family of oxidoreductases, specifically those acting on paired donors, with O<sub>2</sub> as oxidant and incorporation or reduction of oxygen. The oxygen incorporated need not be derived from O<sub>2</sub> with NADH or NADPH as one donor, and incorporation of one atom of oxygen into the other donor. The systematic name of this enzyme class is (S)-N-methylcoclaurine,NADPH:oxygen oxidoreductase (3'-hydroxylating). This enzyme is also called N-methylcoclaurine 3'-hydroxylase and CYP80B1.