Forbidden Coherence Transfer of (19)F Nuclei to Quantitatively Measure the Dynamics of a CF(3)-Containing Ligand in Receptor-Bound States

The dynamic property of a ligand in the receptor-bound state is an important metric to characterize the interactions in the ligand–receptor interface, and the development of an experimental strategy to quantify the amplitude of motions in the bound state is of importance to introduce the dynamic aspect into structure-guided drug development (SGDD). Fluorine modifications are frequently introduced at the hit-to-lead optimization stage to enhance the binding potency and other characteristics of a ligand. However, the effects of fluorine modifications are generally difficult to predict, owing to the pleiotropic nature of the interactions. In this study, we report an NMR-based approach to experimentally evaluate the local dynamics of trifluoromethyl (CF(3))-containing ligands in the receptor-bound states. For this purpose, the forbidden coherence transfer (FCT) analysis, which has been used to study the dynamics of methyl moieties in proteins, was extended to the (19)F nuclei of CF(3)-containing ligands. By applying this CF(3)–FCT analysis to a model interaction system consisting of a ligand, AST-487, and a receptor, p38α, we successfully quantified the amplitude of the CF(3) dynamics in the p38α-bound state. The strategy would bring the CF(3)-containing ligands within the scope of dynamic SGDD to improve the affinity and specificity for the drug-target receptors.