Tryptophan 5-monooxygenase

In enzymology, a tryptophan 5-monooxygenase is an enzyme that catalyzes the chemical reaction

L-tryptophan + tetrahydrobiopterin + O2 rightleftharpoons 5-hydroxy-L-tryptophan + 4a-hydroxytetrahydrobiopterin

The 3 substrates of this enzyme are L-tryptophan, tetrahydrobiopterin, and O2, whereas its two products are 5-hydroxy-L-tryptophan and 4a-hydroxytetrahydrobiopterin.

This enzyme belongs to the family of oxidoreductases, specifically those acting on paired donors, with O2 as oxidant and incorporation or reduction of oxygen. The oxygen incorporated need not be derived from O2 with reduced pteridine as one donor, and incorporation of one ato of oxygen into the other donor. The systematic name of this enzyme class is L-tryptophan,tetrahydrobiopterin:oxygen oxidoreductase (5-hydroxylating). Other names in common use include L-tryptophan hydroxylase, indoleacetic acid-5-hydroxylase, tryptophan 5-hydroxylase, and tryptophan hydroxylase. This enzyme participates in tryptophan metabolism. It employs one cofactor, iron.

Structural studies

As of late 2007, only one structure has been solved for this class of enzymes, with the PDB accession code .


  • Friedman PA, Kappelman AH, Kaufman S "Partial purification and characterization of tryptophan hydroxylase from rabbit hindbrain". J. Biol. Chem. 247 4165–73.
  • Hamon M, Bourgoin S, Artaud F, Glowinski J "The role of intraneuronal 5-HT and of tryptophan hydroxylase activation in the control of 5-HT synthesis in rat brain slices incubated in K+-enriched medium". J. Neurochem. 33 1031–42.
  • Ichiyama A, Nakamura S, Nishizuka Y, Hayaishi O "Enzymic studies on the biosynthesis of serotonin in mammalian brain". J. Biol. Chem. 245 1699–709.
  • Jequier E, Robinson DS, Lovenberg W, Sjoerdsma A "Further studies on tryptophan hydroxylase in rat brainstem and beef pineal". Biochem. Pharmacol. 18 1071–81.
  • Wang L, Erlandsen H, Haavik J, Knappskog PM, Stevens RC "Three-dimensional structure of human tryptophan hydroxylase and its implications for the biosynthesis of the neurotransmitters serotonin and melatonin". Biochemistry. 41 12569–74.

External links

The CAS registry number for this enzyme class is .

Gene Ontology (GO) codes

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