Catalyzes the oxidative demethylation of N-methyl-L-tryptophan. Can also use other N-methyl amino acids, including sarcosine, which, however, is a poor substrate. H2O + N(alpha)-methyl-L-tryptophan + O2 = formaldehyde + H2O2 + L-tryptophan Binds 1 FAD per subunit. Aromatic carboxylates are competitive inhibitors. Optimum pH is 8.0. Monomer. Belongs to the MSOX/MTOX family. MTOX subfamily.