XtalCheck-S

Primarily designed for in-situ screening of protein crystals in their crystallization environment, the XtalCheck-S may also be used to quickly screen powder samples. Once the powder samples have each been secured in a dedicated well, crystallographers will use the data collection program, CrysAlis^Pro, the exact same way they would for single crystals: features such as point-and-click object selection and centering, screening of multiple objects in multiple wells one by one or queuing of a multitude of candidates for subsequent screening without user intervention operate identically regardless of the type of sample.

At Rigaku, an experiment has successfully been performed whereby powder samples were set in dedicated wells which had been previously wetted with a very small amount of PARATONE oil, to prevent powder from falling off when the plate was mounted vertically in front of the beam The powder grains remained still and stable in the wells, allowing all the time needed for screening multiple grains even with longer exposure times. Importantly, thanks to a telescopic sled, the detector was backed up as much as needed to ensure proper resolution of the Debye-Sherrer rings. Lastly, a partial data set was collected by allowing the plate to rotate by about 25° in the beam along omega. Images were automatically merged together by CrysAlis^Pro to generate a single scattering image, from which a 2D plot of I vs. 2θ was seamlessly created by CrysAlis^Pro

Protein crystallography often requires screening large numbers of crystals to identify samples that are suitable for X-ray diffraction experiments. Specifically, crystallographers usually loop and cryo-freeze samples for X-ray screening to identify whether the sample contains a protein or salt and to evaluate diffraction resolution, mosaicity and other crystal parameters. This iterative process of mounting and screening of many samples is time consuming and rarely automated. The XtalCheck-S system addresses this bottleneck by automating diffraction data collection for crystals directly from SBS format crystallization plates. The XtalCheck-S system includes software that facilitates both visual and diffraction imaging of crystallization experiments. With the XtalCheck-S system, one can easily survey many crystallization experiments by eliminating the need to harvest and cryo-cool samples. Moreover, one can perform serial crystallography experiments, by collecting data from multiple crystals, to achieve complete data sets that can be used for structure solution.