Clear strategy screens for macromolecular crystallization

The development of high-throughput crystallography combined with the wealth of already accumulated information about protein crystallization propertie s requires constant revision of current crystallization screening procedure s. Two complementary 6 x 4 matrix 'clear strategy screens' (CSS) have been developed and tested on a number of previously non-crystallized proteins. T he screens yielded diffraction-quality crystals of a wide range of proteins (enzymes, transcription factors, structural proteins, etc.) in cases where the applications of commercially available screens were unsuccessful. Both their inherently simple design and their flexible nature provide an experi menter with a logical platform for further modification and optimization. F urthermore, the screens facilitate cryoprotection and potential incorporati on of anomalous scatterers for multiple/ single-wavelength anomalous disper sion (MAD/SAD) experiments.