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FADH 2 ‐Dependence of Tryptophan 7‐Halogenase
Author(s) -
Unversucht Susanne,
Hollmann Frank,
Schmid Andreas,
van Pée KarlHeinz
Publication year - 2005
Publication title -
advanced synthesis and catalysis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.541
H-Index - 155
eISSN - 1615-4169
pISSN - 1615-4150
DOI - 10.1002/adsc.200505029
Subject(s) - chemistry , flavin group , halogenation , tryptophan , stereochemistry , flavoprotein , reductase , organic chemistry , enzyme , biochemistry , amino acid
Tryptophan 7‐halogenase (Trp 7‐hal) catalyses the regioselective chlorination and bromination of tryptophan. For halogenating activity, Trp 7‐hal requires FADH 2 produced from FAD and NADH by a flavin reductase, halide ions (chloride or bromide), molecular oxygen and tryptophan as the organic substrate. Investigations of the flavin dependence showed that purified Trp 7‐hal itself does not contain flavin. Keeping the Trp 7‐hal separated from the flavin reductase during the reaction revealed that Trp 7‐hal can use diffusible FADH 2 produced by a flavin reductase showing that direct contact between the halogenase and the flavin reductase is not absolutely necessary. Thus, the reaction also proceeds when chemically reduced flavin is used. For the catalytic regeneration of FADH 2 , the organometallic complex (pentamethylcyclopentadienyl)rhodium‐bipyridine {[Cp*Rh(bpy)(H 2 O)] 2+ } can be employed as the redox catalyst with formate as the electron donor. With this chemoenzymatic system about 85% yields of the product formed by the two‐component enzyme system consisting of Trp 7‐hal and a flavin reductase were obtained.