Figure 2: The decarboxylation or tryptamine pathway. Abbreviations used are: ALAAD (aromatic L-amino acid decarboxylase), ALDH (aldehyde dehydrogenase), MAO (monoamine oxidase), NAD(H) [oxidized and (reduced) nicotinamide-adenine dinucleotide], PLP (pyridoxal 5'-phosphate).