EC - Tryptophan 5-monooxygenase

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IntEnz Enzyme Nomenclature


Accepted name:
tryptophan 5-monooxygenase
Other names:
L-tryptophan hydroxylase
indoleacetic acid-5-hydroxylase
tryptophan 5-hydroxylase
tryptophan hydroxylase
Systematic name:
L-tryptophan,tetrahydrobiopterin:oxygen oxidoreductase (5-hydroxylating)




The active centre contains mononuclear iron(II). The enzyme is activated by phosphorylation, catalysed by a Ca2+-activated protein kinase. The 4a-hydroxytetrahydrobiopterin formed can dehydrate to 6,7-dihydrobiopterin, both spontaneously and by the action of EC, 4a-hydroxytetrahydrobiopterin dehydratase. The 6,7-dihydrobiopterin can be enzymically reduced back to tetrahydrobiopterin, by EC (6,7-dihydropteridine reductase), or slowly rearranges into the more stable compound 7,8-dihydrobiopterin.

Links to other databases

Enzymes and pathways: NC-IUBMB , BRENDA , ExplorEnz , ENZYME@ExPASy , KEGG , MetaCyc , UniPathway
Protein domains and families: PROSITE:PDOC00316
Structural data: CSA , EC2PDB
Gene Ontology: GO:0004510
CAS Registry Number: 9037-21-2
UniProtKB/Swiss-Prot: (17) [show] [UniProt]


  1. Friedman, P.A., Kappelman, A.H. and Kaufman, S.
    Partial purification and characterization of tryptophan hydroxylase from rabbit hindbrain.
    J. Biol. Chem. 247 : 4165-4173 (1972). [PMID: 4402511]
  2. Hamon, M., Bourgoin, S., Artaud, F. and 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 : 1031-1042 (1979). [PMID: 315449]
  3. Ichiyama, A., Nakamura, S., Nishizuka, Y. and Hayaishi, O.
    Enzymic studies on the biosynthesis of serotonin in mammalian brain.
    J. Biol. Chem. 245 : 1699-1709 (1970). [PMID: 5309585]
  4. Jequier, E., Robinson, B.S., Lovenberg, W. and Sjoerdsma, A.
    Further studies on tryptophan hydroxylase in rat brainstem and beef pineal.
    Biochem. Pharmacol. 18 : 1071-1081 (1969). [PMID: 5789774]
  5. Wang, L., Erlandsen, H., Haavik, J., Knappskog, P.M. and Stevens, R.C.
    Three-dimensional structure of human tryptophan hydroxylase and its implications for the biosynthesis of the neurotransmitters serotonin and melatonin.
    Biochemistry 41 : 12569-12574 (2002). [PMID: 12379098]

[EC created 1972, modified 2003, modified 2019]