Some Properties of Bovine Pineal Tryptophan Hydroxylase

The conversion of L-tryptophan to L-5HTP is the first step in the biosynthesis of serotonin in the brain and of melatonin in the pineal gland and is catalyzed by tryptophan hydroxylase. Since the first demonstration by Grahame-Smith that a specific tryptophan hydroxylase exists in the brain (1), the enzyme has been studied at various laboratories including our own (2–11) and is now accepted as a pterin-dependent aromatic amino acid monooxygenase (12).