The most rigorous way to optimize a drug lead is to determine the X-ray crystal structures of the Target-lead complex. This provides the basis for a protein engineering campaign to optimize the lead. Co-crystal structures are solved to obtain more information and optimize interaction.
X-ray crystallography is also used to identify druggable regions on the target. This is especially important for membrane proteins, which are prime drug candidates, but are typically very difficult to purify.
PhyTip technology purifies proteins to high concentrations suitable for structural analysis. But more important, with method development, separation conditions can be screened (with different surfactants and different concentration for example) to produce stable and functional membrane proteins.