Adenosine A Receptor (AAR) Ligand Screening Using the F-NMR Probe FPPA.

The binding affinity of G protein-coupled receptor (GPCR) ligands is customarily measured by radio-ligand competition experiments. As an alternative approach, F nuclear magnetic resonance spectroscopy (F-NMR) is used for the screening of small-molecule lead compounds in drug discovery; the two methods are complementary in that the measurements are performed with widely different experimental conditions. Here, we used the structure of the A adenosine receptor (AAR) complex with (3-(4-amino-3-methylbenzyl)-7-(furan-2-yl)-3-[1,2,3]triazolo[4,5-]pyrimidin-5-amine) as the basis for the design of a fluorine-containing probe molecule, (4-(furan-2-yl)-7-(4-(trifluoromethyl)benzyl)-7-pyrrolo[2,3-]pyramidin-2-amine), for binding studies with AAR. A protocol of experimental conditions for drug screening and measurements of drug binding affinities using 1D F-NMR observation of is validated with studies of known AAR ligands. F-NMR with is thus found to be a robust approach for the discovery of ligands with new core structures, which will expand the libraries of AAR-targeting drug candidates.