L-3-Cyanophenylalanine is primarily used in biochemical research as a non-natural amino acid. It serves as a valuable tool in studying protein structure and function, particularly in fluorescence spectroscopy and Förster resonance energy transfer (FRET) experiments. Its unique cyanophenyl group allows for specific labeling and tracking of proteins, enabling researchers to monitor protein interactions, folding, and dynamics in real-time. Additionally, it is employed in the development of enzyme inhibitors and probes for understanding enzymatic mechanisms. Its incorporation into peptides and proteins aids in exploring biological pathways and designing novel therapeutic agents.