Studying protein-ligand interactions using X-ray crystallography.

X-ray crystallography is a powerful technique for studying protein-ligand interactions. Advances in techniques have meant that it is now possible to routinely determine the structures of ligand complexes in the majority of cases where crystallization conditions and protein structures are already known. Ligand soaking or cocrystallization, together with the potential use of molecular replacement, provides data for determining the structures of a protein in complex with ligands. Furthermore, advances in protein structure model building facilitate automatic ligand fitting to residual electron density in the protein-ligand complex.