analog is tryptamine . Tryptamine then undergoes a transmethylation ( step 2 ): the enzyme indolethylamine-N-methyltransferase (INMT) catalyzes the transfer of a methyl group from cofactor S-adenosyl-methionine (SAM), via nucleophilic attack, to tryptamine. This reaction transforms SAM into S-adenosylhomocysteine (SAH), and gives the intermediate product N -methyltryptamine (NMT). NMT is in