Small molecule crystallography in drug design.

Crystal structures of small molecules (i.e. isolated ligands) are a source of valuable structural information helpful in the process of drug design (pharmacophore model elaborations, 3D QSAR, docking, and de novo design). Indeed, structural data obtained from small molecules crystallography can approach ligand-receptor binding by providing unique structural features both about the conformation (internal geometry) of the ligand (s) and about the intermolecular interaction potentially occurring within the active site of a target (enzyme/receptor). Small molecule crystal structure databases can also be used in three dimensional search to identify new drug candidates. Future development in small molecule crystallography (e.g. powder diffraction) should also provide original solutions to complex problems related to polymorphism.