“…The use of 19 F-containing ligands to probe protein-ligand interactions by NMR is also well established (Chen et al, 2013;Fielding, 2007;Ghitti et al, 2014;Hortin & Boime, 1983). 19 F-containing ligand-observe experiments have been used to provide information on ligand-binding affinity, specificity, and reversibility and to obtain ligandprotein structural constraints (Clore, Gronenborn, Birdsall, Feeney, & Roberts, 1984;Goudreau, Coulombe, & Faucher, 2013;Kim et al, 1990;Matei et al, 2013;Yu, Hajduk, Mack, & Olejniczak, 2006).…”