SR instrumentation for optimized anomalous scattering and high resolution structure studies of proteins and nucleic acids (invited)

Crystal structure solution by anomalous dispersion methods has been greatly facilitated using the rapidly tunable station 9.5 at the Daresbury SRS. Both SIROAS and MAD techniques, with IP data, have been used in the phasing of a brominated nucleotide and a seleno deaminase, respectively. The electron density maps in each case are interpretable. Throughput of projects could be improved upon with a better duty cycle detector. Another category of data collection is that at very high resolution. Detailed structure refinement pushes the limits of resolution and data quality. Station 9.5 has been used to collect high resolution (1.4 A) native data for the protein concanavalin A. This utilized very short wavelengths (0.7 A), the image plate, and crystal freezing. A total of 155 407 measurements from two crystals benefited from the on‐line nature of the IP detector device, but a slow and quick pass are required to capture the full dynamic range of the data. There are data seen to 1.2 A and beyond for a pure Mn su...