There are three key areas to consider when optimising crystal quality. Firstly, the protein itself where purity, concentration, stability and buffer can all impact the crystal generation.
Secondly, the chemical components (precipitant) used in a screen which gives rise to a crystal. Varying the polymer chain length, anions or cations in the salts and pH are all important variables to test. Thirdly, how the experiment is set-up can greatly alter the formation of crystals. We use a number of different formats such as sitting or hanging drops, in gels, lipidic cubic phases, robotically at nL up to mL scale and at different temperatures. Seeding from initial crystal hits can produce dramatic improvements in quality as well as new crystal forms.