Revealing protein structures: crystallization of protein-ligand complexes – co-crystallization and crystal soaking

Protein crystallogenesis represents a key step in X-ray crystallography studies that employ co-crystallization and ligand soaking for investigating ligand binding to proteins. Co-crystallization is a method that enables the precise determination of binding positions, although it necessitates a significant degree of optimization. The utilization of microseeding can facilitate a reduction in sample requirements and accelerate the co-crystallization process. Ligand soaking is the preferred method due to its simplicity; however, it requires careful control of soaking conditions to ensure the successful integration of the ligands. This research protocol details the procedures for co-crystallization and soaking to achieve protein–ligand complex formation, which is essential for advancing drug discovery. Additionally, a simple protocol for demonstrating soaking for educational purposes is described.