EC - Tryptophan 7-halogenase

  IntEnz view ENZYME view

IntEnz Enzyme Nomenclature


Accepted name:
tryptophan 7-halogenase
Other names:
prnA (gene name)
rebH (gene name)
ktzQ (gene name)
Systematic name:
L-tryptophan:FADH2 oxidoreductase (7-halogenating)



A flavin-dependent halogenase. The enzyme from the bacterium Lechevalieria aerocolonigenes catalyses the initial step in the biosynthesis of rebeccamycin [2]. 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. Also acts on bromide ion. cf. EC, tryptophan 5-halogenase, and EC, tryptophan 6-halogenase.

Links to other databases

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


  1. Dong, C., Kotzsch, A., Dorward, M., van Pee, K. H., Naismith, J. H.
    Crystallization and X-ray diffraction of a halogenating enzyme, tryptophan 7-halogenase, from Pseudomonas fluorescens.
    Acta Crystallogr. D Biol. Crystallogr. 60: 1438-1440 (2004). [PMID: 15272170]
  2. Yeh, E., Garneau, S., Walsh, C. T.
    Robust in vitro activity of RebF and RebH, a two-component reductase/halogenase, generating 7-chlorotryptophan during rebeccamycin biosynthesis.
    Proc. Natl. Acad. Sci. USA 102: 3960-3965 (2005). [PMID: 15743914]
  3. Bitto, E., Huang, Y., Bingman, C. A., Singh, S., Thorson, J. S., Phillips, G. N.
    The structure of flavin-dependent tryptophan 7-halogenase RebH.
    Proteins 70: 289-293 (2008). [PMID: 17876823]
  4. Heemstra, J. R., Walsh, C. T.
    Tandem action of the O2- and FADH2-dependent halogenases KtzQ and KtzR produce 6,7-dichlorotryptophan for kutzneride assembly.
    J. Am. Chem. Soc. 130: 14024-14025 (2008). [PMID: 18828589]

[EC created 2009 as EC, transferred 2014 to EC,modified 2018]