This proposal requests funds for the acquisition of an X-ray diffractometer to be located in the Analytical Services Laboratory (ASL) at the Evanston Campus of Northwestern University and for data collection equipment for the macromolecular/small molecule crystallography station at the Advanced Photon Source (APS) at Argonne National Laboratory. These instruments will greatly facilitate the research and teaching efforts of Northwestern University researchers in two very basic ways. First, the ASL X-ray diffractometer will greatly improve productivity by providing the numerous advantages of "electronic film", including significant reduction in data collection times. Second, the APS equipment will provide a unique tool not only for the rapid collection of data from macromolecular crystals but also for the collection of data from microcrystals of inorganic and organic materials. Structure determinations of a wide range of inorganic and organic materials with the use of our present X-ray diffractometers typically require several days to several weeks for data collection, limiting the number of structures that can be analyzed. A more severe problem arises owing to the inherent limitations in signal-to-noise of our point detectors in front of sealed tubes. The major users listed in this proposal all encounter "difficult" problems: the availability of only very small crystals, superlattice/sublattice considerations, twinned crystals, diffuse scattering, crystals with very large unit cells, and crystals that are sensitive to radiation. With the current diffractometers many of these problems are not resolved. An X-ray diffractometer equipped with a lK CCD or image-plate area detector and a rotating anode generator is ideally designed to address the crystallographic needs of the major users. With the increased signal-to-noise available from such an instrument, data collection times for routine crystals will be greatly reduced. This will significa ntly improve turn-around time for most samples, will reduce the costs involved, and hence will make the facility available for a wider range of problems to a larger number of users. This is especially important to our students, who will have far greater access to modern X-ray instrumentation than they do at present. In addition, most of the "difficult" problems will be amenable to solution on such an instrument. Some will remain, for example the existence of only microcrystals, and these will be addressed at the APS facility. The APS facility is also used for macromolecular crystallography. The requested CCD detector will enhance and upgrade the current capabilities of the beam line operated by the Collaborative Access Team formed by Northwestern University in collaboration with DuPont de Nemours & Co. and The Dow Chemical Co. (DND-CAT). At present, there are no facilities for macromolecular crystallography at the DND-CAT beam line. The proposed two-dimensional data collection instrument will be mounted on a kinematic table that will have built-in capabilities to accommodate a CCD detector. The necessary computer hardware to operate the detector and to process data on-site are also part of the proposed facility. Indeed, these complementary facilities will provide a truly one-of-kind learning environment for both students and faculty. Personnel from the Department of Chemistry and the Department of Biochemistry, Molecular Biology, and Cell Biology on the Evanston Campus and the Department of Molecular Pharmacology and Biological Chemistry of the Medical School Campus in Chicago will interact with both academic and industrial scientists from a variety of fields.
