The goal of this proposal is to provide partial funding for a second X-ray area detector for use in the Molecular Biophysics Dept. of the Hauptman-Woodward Medical Research Institute, and for the refurbishing and modification of the existing Rigaku R-Axis II. This equipment is to be shared by a major user group consisting of six principal investigators who are conducting research funded by the PHS and a number of projects funded by other means. The requested funds will be used to purchase a Rigatu ~UltraX" rotating anode generator, an ADSC four module CCD detector system, focusing mirrors, K goniostat and low temperature device, and a dedicated SGI workstation. The presence of a second detector will permit the modification of the existing R-Axis II, which is equipped with a graphite monochromator, to unable routine target changes. The addition of the monochromator pivot and three-axis readout and the acquisition of a Cr target win allow target changes while minimizing down time. The instrument can then be used for normal data collection (Cu), and to exploit anomalous scattering techniques in direct methods, maximizing the anomalous signal by using the longest wavelength practical (Cr). Additionally, the image plates, laser, bearings, belts and Be window, which are nearing the end of their expected life, will be replaced. An internal advisory committee consisting of the Institute's President, Executive Vice-President-- Research, and the Head of the Molecular Biophysics Dept. will have overall responsibility for the equipment, and the day-to-day management will be provided by the staff scientist who presently supervises the Institute's shared diffraction facilities, assisted by two other members of the department's scientific staff. The projects to be served by this equipment include the study of steroid metabolizing enzymes, steroid transport proteins, ion transport antibiotics, dihydrofolate reductase/inhibitor complexes, transthyretin complexes, estrogen aromatase and its complex with a monoclonal antibody, folylpolyglutamate synthetase, xylan esterases, and bovine duodenase, as well as the research on new methods of phase determination. The total cost of the acquisition of this equipment and modification of existing equipment will be reduced by an amount of $230,000 already obtained from private sources for the purpose of expanding the protein diffraction facilities.