In protein-observed methods, the most typical parameter and the easiest to follow is the chemical shift. Chemical shift perturbations of the protein resonances observed on ligand addition are identified to localize the ligand binding site. This enables one to immediately distinguish specific from non-specific binding. The 3D structure of the protein–ligand complex can be resolved via heteronuclear experiments performed on isotopically labelled (13C, 15N, 2H) protein samples. The structure resolution requires molecular dynamics calculations with experimental NMR restraints resulting from chemical shifts, scalar couplings, nuclear Overhauser effects (NOEs), paramagnetic interactions or dipolar couplings

 ligand-binding-CSP ligand-binding