Beamline for Biological Macromolecular Assemblies (BL44XU) at SPring-8

Abstract

To reveal the function of the biological macromolecular assemblies at atomic level, three‐dimensional structure of the complex molecules is essential. The beamline including detectors is designed to collect high resolution and high quality diffraction data from macromolecular assembly crystals with large unit cells. This beamline uses a standard undulator of SPring‐8 as a light source. X‐rays from the undulator are monochromatized by a liquid nitrogen cooled double crystal. The monochromatized X‐ray beam is collimated or focused reflected by a Rhodium‐coated mirror, and it is also used for elimination of higher‐order harmonics. At downstream of the Beryllium window, we place a fast shutter system, two quadrant slit systems, and an ionization chamber in this order. Size of the X‐ray‐beam can be changed by the slit systems from 1 μm to fully‐open. Typical photon flux is about 1011 photons/sec. with the slit size of 0.07 × 0.07 mm2 at 0.9 A. A sample is cooled either to 90K by a nitrogen or to 30K by a helium cryo‐stream system. A DIP6040, which is a hybrid‐type of image plates and a CCD, is used for data collection. The DIP6040 has six image plates with individual readout systems, and effective area of each image plate is circular with 400 mm in diameter. A 185 mmφ CCD detector can be used both for data collection and screening of the crystals. Frame rate of the image plate system can be achieved to 120 images per hour at maximum.