|Budget Amount *help
¥24,500,000 (Direct Cost : ¥24,500,000)
Fiscal Year 1991 : ¥2,300,000 (Direct Cost : ¥2,300,000)
Fiscal Year 1990 : ¥22,200,000 (Direct Cost : ¥22,200,000)
The objective of this. research project is to establish a system for direct and rapid structure determination of protein crystals by use of tunable and intense synchrotron X-radiation.
First, a dead time correction method for scintillation detectors and automatic optimization procedures for alignment of the X-ray optical components were newly developed for the diffraction intensity measurement system, which consists of the double-crystal monochromator, focussing mirror, and horizontal-type four-circle diffractometer, installed at Photon Factory, National Laboratory for High Energy Physics. The measurement system improved so as to accommodate these procedures is applicable to four-circle diffractometry as well as to oscillation methods, and provides excellent-quality diffraction data at any practical wavelengths. The system has been in open use to various synchrotron experiments. Next, a kappa-axis diffractometer-with a sealed X-ray tube was equipped with a portable crystal-cooling unit
which decreases radiation damages on protein crystals. Finally, computer programs for processing diffraction data measured at several wavelengths as well as for direct phasing of crystal structure factors were developed. The programs combined with structure refinement, graphics, and other programs were built into a complete system for multiwavelength anomalous diffraction analyses.
Crystal Structure of an Fv fragment from mouse anti-dansyllysine immunoglobulin IgG2a has been determined at 2.5 * resolution. The structure clearly elucidates its complementarity determining regions. Structure refinements of the native crystal and a dansyllysine complex crystal are in progress at hislier resolution. Furthermore, crystal structures of ferous spincrossover complexes as well as those of aspartaine IA and IB forms liave been solved in the course of performance tests of the measurement and proprain systems.
The systems established in this research project are widely applicable to crystal structure studies of proteins and others. Less