CAS 138514-97-3: L-Tryptophan, 7-fluoro-

7-Fluoro-L-tryptophan

7-Fluoro-L-tryptophan is a fluorinated analog of L-tryptophan. Fluorine substitution for hydrogen in the phenyl ring of the molecule increases the photophysical, biological and fluorogenic properties of 7-fluoro-L-tryptophan. It has been shown to have higher potency than L-tryptophan in both clinical and preclinical studies and can be used as a positron emission tomography radiotracer. The method of synthesis involves reacting 7-fluoroindole with tertiary amines. This synthetic procedure is more difficult than that for L-tryptophan, but yields a more pure product. The subunits are synthesized by recombinant microbial fermentation using Escherichia coli bacteria strains such as BL21 (DE3) pLysS or BL21 (DE3) pLysE.