Specific enzymatic chlorination of tryptophan and tryptophan derivatives
1Technische Universität Dresden, Institut für Biochemie, Germany. Karl-Heinz.vanPee@chemie.tu-dresden.de
Abstract:
In the search for an alternative to chemical halogenation reactions using the free halogens, a novel type of halogenating enzymes was detected. In contrast to haloperoxidases, these NADH-dependent halogenases are specific. Tryptophan halogenase which catalyses the regioselective chlorination of tryptophan to 7-chlorotryptophan can also chlorinate tryptamine, tryptophol, indole-3-acetonitrile, and 3-methylindole. However, indole-3-acetonitrile is not chlorinated in the 7-position, but in positions two and three of the indole ring. Chlorination in the 3-position is obviously stereospecific. In addition to tryptophan and indole derivatives, aminophenylpyrrole is also accepted as a substrate for regioselective chlorination. Since the new NADH-dependent halogenases have a fairly broad substrate specificity and catalyse regioselective chlorination reactions they could be a good alternative to chemical halogenation.
Related Concept Videos
Reactions at the Benzylic Position: Halogenation
Electrophilic Aromatic Substitution: Chlorination and Bromination of Benzene
Electrophilic Aromatic Substitution: Fluorination and Iodination of Benzene
Amino Acid Biosynthetic Pathways
Repressible Operon: trp Operon
Microbial Bioremediation of Pesticides

![Radiosynthesis of 1-(2-[18F]Fluoroethyl)-L-Tryptophan using a One-pot, Two-step Protocol](/_next/image?url=https%3A%2F%2Fcloudfront.jove.com%2FCDNSource%2Fteasers%2F63025.jpg&w=3840&q=50)
