5-Fluoro-L-tryptophan is a competitive inhibitor of the vesicular glutamate transporter (VGLUT). Generally regarded as a fluorinated analogue of tryptophan, it is frequently used as a fluorescent probe or a nuclear magnetic resonance (NMR) probe in protein structure studies.
Exogenous 5-fluoro-Trp is incorporated into proteins in normal protein synthesis. Since 19F is a useful reporter group, this provides a method for studying enzyme mechanisms by NMR.
5-Fluoro-Trp is nonspecifically cytotoxic. It is believed this is due to malfunctioning enzymes that have had replacements of Trp residues by 5-fluoro-Trp. However, at least one case is known where 5-fluoro-Trp substitution leads to significantly greater catalytic activity.
Recrystallise it from EtOH, aqueous EtOH or AcOH. Also purify it by passage through a Dowex AG1x2 (acetate form) column and recrystallise the L-enantiomer (from enzymic enrichment) from H2O/EtOH, m 158-163o(dec), [] D -8.3o (c 2.5, N NaOH). [Coy et al. Biochemistry 13 3550 1974, Beilstein 22/14 V 116.]
