Abstract
Fragment-based drug design plays an important role in drug discovery. Protein-observed NMR experiments with isotopically labeled samples are used to probe target-ligand interactions and map the ligand-binding sites. Here, we present a protocol to perform fragment screening using NMR spectroscopy. We describe steps for producing 15N-labeled Kirsten rat sarcoma viral oncogene homolog (KRAS) G12D protein, fragment screening using 1H-15N-heteronuclear single quantum coherence (HSQC) experiment, fragment deconvolution, determining binding affinities, and mapping the fragment-binding site. This protocol provides a strategy in fragment screening.