Cryptic binding sites in protein-ligand complexes

Binding site is a region on a macromolecule such as a protein that binds to another molecule with specificity. Some pockets or concave site can already exist in a ligand-free structure of a protein. Sometimes, a binding site is flat in the absence of a ligand and only forms in the presence of a ligand (i.e., induced fit) or only opens transiently for short periods of time (i.e., conformational selection); such binding sites are called cryptic sites. Cryptic pockets : not easily detectable in the APO state, requires conformational changes to become apparent, and requires a ligand to be detected. These sites can be important for drug discovery because they can provide previously undescribed pockets and thus enable targeting of proteins that would otherwise be considered undruggable. Conventional approaches for cryptic site discovery: experimentally by fragment-based ligand discovery and computationally by long molecular dynamics simulations, fragment docking, identifications of small mol...