Reaction: L-tryptophan + FADH2 + chloride + O2 + H+ = 5-chloro-L-tryptophan + FAD + 2 H2O
For diagram of reaction click here.
Other name(s): pyrH (gene name)
Systematic name: L-tryptophan:FADH2 oxidoreductase (5-halogenating)
Comments: 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 1.14.19.59, tryptophan 6-halogenase and EC 1.14.19.9, tryptophan 7-halogenase.
Links to other databases: BRENDA, EXPASY, KEGG, MetaCyc, CAS registry number:
References:
1. Zehner, S., Kotzsch, A., Bister, B., Sussmuth, R.D., Mendez, C., Salas, J.A. and van Pee, K.H. A regioselective tryptophan 5-halogenase is involved in pyrroindomycin biosynthesis in Streptomyces rugosporus LL-42D005. Chem. Biol. 12 (2005) 445-452. [PMID: 15850981]
2. Zhu, X., De Laurentis, W., Leang, K., Herrmann, J., Ihlefeld, K., van Pee, K.H. and Naismith, J.H. Structural insights into regioselectivity in the enzymatic chlorination of tryptophan. J. Mol. Biol. 391 (2009) 74-85. [PMID: 19501593]