A New Design of Protein Crystallization Plates to Expand Concentration Screening Space in Cross-Diffusion Microbatch and Microbatch Methods

Protein crystallizes at specific conditions (correct precipitants, appropriate concentrations of protein and precipitants, suitable pH and correct temperature, etc.). If the conditions are not appropriate, crystallization will not occur. In protein crystallization screening, the target protein is mixed one by one with many chemical agents and then incubated at a set temperature. If the concentrations of the chemical agents and the target proteins are not in a range suitable for crystallization, the crystallization will not occur. To expand the concentration screening space, we propose in this paper a new design of protein crystallization plates for cross-diffusion microbatch and microbatch methods. The new plates have 96 units corresponding to the conditions of the commercial screening kits, and each unit contains four wells for holding the crystallization droplets. By dispensing crystallization droplets to the four wells at different volume ratios of protein to precipitant solutions, we can obtain four different initial concentrations for each unit, and thus a wider concentration range can be screened. The comparison between the screening performance of the new plates and the traditional sitting-drop vapor diffusion plate showed that the new design of the plates exhibited significantly improved results in obtaining more crystallization conditions.