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 1.14.19.58, tryptophan 5-halogenase, and EC 1.14.19.9, tryptophan 7-halogenase.
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 1.14.19.58, tryptophan 5-halogenase, and EC 1.14.19.9, tryptophan 7-halogenase.
enzyme catalyses the regioselective chlorination and bromination of L- and D-tryptophan. In vitro activity of the purified enzyme can only be shown in a two-component enzyme system consisting of the halogenase, a flavin reductase, NADH, FAD and halide ions
enzyme catalyses the regioselective chlorination and bromination of L- and D-tryptophan. In vitro activity of the purified enzyme can only be shown in a two-component enzyme system consisting of the halogenase, a flavin reductase, NADH, FAD and halide ions
the first step in thienodolin biosynthesis is catalyzed by a tryptophan 6-halogenase, and the last step is the formation of a carboxylic amide group catalyzed by an amidotransferase. Gene ThdH encodes tryptophan 6-halogenase, which catalyzes the regioselective chlorination of tryptophan to 6-chlorotryptophan. This flavin-dependent halogenase requires the participation of a flavin reductase, which is encoded by thdF. A gene deletion mutant of tryptophan 6-halogenase ThdH is not able to produce thienedolin
transformation of the pyrrolnitrin producer Pseudomonas chlororaphis ACN with a plasmid containing the tryptophan 6-halogenase gene leads to the formation of the aminopyrrolnitrin derivative 3-(2'-amino-4'-chlorophenyl)pyrrole
transformation of the pyrrolnitrin producer Pseudomonas chlororaphis ACN with a plasmid containing the tryptophan 6-halogenase gene leads to the formation of the aminopyrrolnitrin derivative 3-(2'-amino-4'-chlorophenyl)pyrrole
the first step in thienodolin biosynthesis is catalyzed by a tryptophan 6-halogenase, and the last step is the formation of a carboxylic amide group catalyzed by an amidotransferase. Gene ThdH encodes tryptophan 6-halogenase, which catalyzes the regioselective chlorination of tryptophan to 6-chlorotryptophan. This flavin-dependent halogenase requires the participation of a flavin reductase, which is encoded by thdF. A gene deletion mutant of tryptophan 6-halogenase ThdH is not able to produce thienedolin
mutant exhibits similar activity to the wild-type SttH, with tryptophan as a substrate, but produces 32% 5-chlorotryptophan and 68% 6-chlorotryptophan, whereas the wild-type SttH only produces the 6-chlorinated product. with substrate 3-indolepropionic acid, mutant gives 75% 5-chloro-3-indolepropionic acid
site-directed, structure-guided mutagenesis, the mutant exhibit similar activity to the wild-type SttH, with tryptophan as a substrate, but shows a complete switch in regioselectivity compared to the wild-type enzyme without impacting on catalytic efficiency: 75% 5-chlorination is observed for the substrate 3-indolepropionate with the mutant in comparison to 90% 6-chlorination of 3-indolepropionate for the wild-type SttH. SttH is more like PyrH than PrnA, with insertions present in PyrH and SttH between residues SttH 155 and 167 and a deletion between SttH 457 and 464 compared with PrnA, the mutation, the only differences evident in the active-site region between the structures of PyrH and SttH are those of PyrH residues F451, E452 and T453 and SttH L460, P461 and P462. These residues are of particular interest because they are in close proximity to the active site in PyrH and SttH, and are positioned directly above the alpha-amino acid moiety of the substrate, tryptophan. Moreover, there isa loop insertion in PrnA in this region that is suggested to contribute to its regioselectivity. Each of these residues is mutated in SttH to the corresponding residue in PyrH, that is, L460F, P461E and P462T. Individually, each mutation reduces the relative activity of the enzyme with tryptophan, but does not have a significant effect on the observed regioselectivity, with 6-chlorotryptophan remaining the major product
gene stth, functional recombinant expression of Yfp-tagged enzyme in Nicotianan benthamiana leaves via Agrobacterium tumefaciens strain EHA105 tranfection method under control of the CaMV 35S promoter leading to formation of 6-chlorotryptophan, coexpression with gene rebF from Lechevalieria aerocolonigenes, different genetic constructs, overview. Coexpression and concerted activity of Stth and tryptophan 7-halogenase RebH, EC 1.14.19.9, lead to formation of 6,7-halotryptophan
development of a quantitative halogenase assay based on a Suzuki-Miyaura cross-coupling towards the formation of a fluorescent aryltryptophan and optimization for application in crude Escherichia coli lysate
1.14.19.59 tryptophan 6-halogenase
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