EC - Tryptophan 6-halogenase

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IntEnz Enzyme Nomenclature


Accepted name:
tryptophan 6-halogenase
Other names:
thdH (gene name)
sttH (gene name)
Systematic name:
L-tryptophan:FADH2 oxidoreductase (6-halogenating)



The enzyme is a flavin-dependent halogenase that has been described from several bacterial species. It utilizes molecular oxygen to oxidize the FADH2 cofactor, giving C4a-hydroperoxyflavin, which then reacts with chloride to produce a hypochlorite ion. The latter reacts with an active site lysine to generate a chloramine, which chlorinates the substrate. cf. EC, tryptophan 5-halogenase, and EC, tryptophan 7-halogenase.

Links to other databases

Enzymes and pathways: NC-IUBMB , BRENDA , ExplorEnz , ENZYME@ExPASy , KEGG , MetaCyc , UniPathway
Structural data: CSA , EC2PDB


  1. Zeng, J., Zhan, J.
    Characterization of a tryptophan 6-halogenase from Streptomyces toxytricini.
    Biotechnol. Lett. 33: 1607-1613 (2011). [PMID: 21424165]
  2. Milbredt, D., Patallo, E. P., van Pee, K. H.
    A tryptophan 6-halogenase and an amidotransferase are involved in thienodolin biosynthesis.
    Chembiochem 15: 1011-1020 (2014). [PMID: 24692213]
  3. Shepherd, S. A., Menon, B. R., Fisk, H., Struck, A. W., Levy, C., Leys, D., Micklefield, J.
    A Structure-Guided Switch in the Regioselectivity of a Tryptophan Halogenase.
    Chembiochem 17: 821-824 (2016). [PMID: 26840773]

[EC created 2018]