Protein-Observed Fluorine NMR: A Bioorthogonal Approach for Small Molecule Discovery.

The (19)F isotope is 100% naturally abundant and is the second most sensitive and stable NMR-active nucleus. Unlike the ubiquitous hydrogen atom, fluorine is nearly absent in biological systems, making it a unique bioorthogonal atom for probing molecular interactions in biology. Over 73 fluorinated proteins have been studied by (19)F NMR since the seminal studies of Hull and Sykes in 1974. With advances in cryoprobe production and fluorinated amino acid incorporation strategies, protein-based (19)F NMR offers opportunities to the medicinal chemist for characterizing and ultimately discovering new small molecule protein ligands. This review will highlight new advances using (19)F NMR for characterizing small molecule interactions with both small and large proteins as well as detailing NMR resonance assignment challenges and amino acid incorporation approaches.