BIOSYNTHESIS OF 5-T DH L-Tryptophan o In animals including N humans. serotonin is synthesized from the amino acid L-tryptophan Hydraxytetra by a short metabolic pathway consisting of two enzymes tryptophan 5-Hydroxy-L-tryptophan (5-HTP) NH2 hydroxylase (TPh) and aromatic amino acid decarboxylase resonate 5-Hydroxytryptophan decarboxylase ①DDC. The TH mediated reaction is the rate-limiting step in the pathway Serotonin (5-HT) NH? o tPh has been shown to O2 HzO Monoamine oxidase (MAO). exist in two forms: TPH1 Aldehyde dehydrogenase NH H> found in several tissues and tph2. which is a neuron-specific isoform OH 5-Hydroxyindoleacetic acid (5-HIAA)BIOSYNTHESIS OF 5-HT  In animals including humans, serotonin is synthesized from the amino acid L-tryptophan by a short metabolic pathway consisting of two enzymes: tryptophan hydroxylase (TPH) and aromatic amino acid decarboxylase (DDC). The TPH￾mediated reaction is the rate-limiting step in the pathway.  TPH has been shown to exist in two forms: TPH1, found in several tissues, and TPH2, which is a neuron-specific isoform