EC - Tryptophan 5-halogenase

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IntEnz Enzyme Nomenclature


Accepted name:
tryptophan 5-halogenase
Other name:
pyrH (gene name)
Systematic name:
L-tryptophan:FADH2 oxidoreductase (5-halogenating)



A flavin-dependent halogenase. The enzyme from the bacterium Streptomyces rugosporus catalyses halogenation of the C-5 position of tryptophan during the biosynthesis of the antibiotic compound pyrroindomycin B. 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 6-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. Zehner, S., Kotzsch, A., Bister, B., Sussmuth, R. D., Mendez, C., Salas, J. A., van Pee, K. H.
    A regioselective tryptophan 5-halogenase is involved in pyrroindomycin biosynthesis in Streptomyces rugosporus LL-42D005.
    Chem. Biol. 12 : 445-452 (2005). [PMID: 15850981]
  2. Zhu, X., De Laurentis, W., Leang, K., Herrmann, J., Ihlefeld, K., van Pee, K. H., Naismith, J. H.
    Structural insights into regioselectivity in the enzymatic chlorination of tryptophan.
    J. Mol. Biol. 391 : 74-85 (2009). [PMID: 19501593]

[EC created 2018]