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

The ¹⁹F 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 ¹⁹F NMR since the seminal studies of Hull and Sykes in 1974. With advances in cryoprobe production and fluorinated amino acid incorporation strategies, protein-based ¹⁹F NMR offers opportunities to the medicinal chemist for characterizing and ultimately discovering new small molecule protein ligands. This review will highlight new advances using ¹⁹F 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.