Glycerol concentrations required for the successful vitrification of cocktail conditions in a high-throughput crystallization screen

The Hauptman-Woodward Medical Research Institute runs a high-throughput crystallization screening service in which macromolecules are screened against 1536 potential crystallization cocktails. Typically, multiple crystallization leads are identified. With a limited amount of sample, the question becomes "How many leads can be optimized and which leads are most likely to produce X-ray diffraction data?". In order to prioritize the hits for optimization, the amount of glycerol required to successfully cryocool each cocktail has been determined for the cocktails used in the high-throughput screen. Those hit conditions that require the minimum amount of cryoprotectant for successful vitrification will be closer in chemical make-up to the mother liquor. Hence, if the physical properties of the crystals are similar, one could logically prioritize leads that are more likely to produce diffraction based upon the chemical similarity of the native to the cryopreserved mother liquor.