X-ray Diffraction Equipment for Macromolecular Crystallography at York

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Understanding molecular structure, that is the 3D shape of a molecule, is often the key to understanding how that molecule performs its function. This is particularly true for large biological molecules that orchestrate the biochemical processes that maintain living cells. An important method of determining the structure of proteins is first to grow crystals of these proteins and then to record their scattering of X-rays by what is termed X-ray diffraction. By collecting a series of X-ray images at different crystal orientations, we accumulate three-dimensional data sets consisting of 10,000 - 500,000 'observations'. Using computational methods we can then use these data to 'solve' (define the positions of atoms) the structure of the protein as it exists in the crystal. With its broad interest in the biological mechanisms of protein action and the exploitation of proteins for biotechnological and biomedical applications, the Structural Biology Laboratory generates 1000s of protein crystals a year. Here we are requesting funds to renew our suite of X-ray diffraction equipment including an X-ray generator, a detector for measuring X-ray diffraction by crystals, and a robot arm that can automatically and serially place crystals into the X-ray beam. Using this apparatus, we can test approximately 3000 crystals each year. We reject crystals that are of insufficient quality for structure determination and we prioritise the best crystals (~1000) for data collection. These crystals are sent to a synchrotron, the DIAMOND Light Source (DLS), a national facility where super-intense X-ray beams are generated. At DLS we can obtain high resolution diffraction data rapidly and accurately. Beam time at DLS is a valuable and limited resource and demand for beam time exceeds beam availability. Our laboratory has one shift every month on average. For this reason, the pre-screening of crystals in our own laboratory is essential for the efficient use of the DLS resource, so that the beam time is used to collect useful data rather than crystal testing. The productivity of the laboratory is evidenced by the submission of ~700 crystal structures into a publicly accessible database, called the Protein Data Bank, and the publication in peer-reviewed journals of 310 papers describing these structures. The structures we have determined are underpinning the development of improved washing powders, the science of biomass conversion for biofuels and the development of new medicines.