Protein crystal growing is one of the most important processes in macromolecular crystallography technique, while it is a very complicated and difficult process too. Many proteins, especially the membrane proteins, have difficulties in growing single crystals of sufficient orderliness and size. If protein crystallography with micro-sized crystals could be achieved, the efficiency and success rate will be greatly improved.
Protein micro-crystallography beamline should be able to deal with the micro-crystals of size down to a few microns. This will make many formidable tasks of structural determination much easier. It is also the typical crystal size of lipid-cubic-phase crystallization method, developed for the membrane protein crystal growth. This beamline is designed to provide stable and highly brilliant micro-beam. It is expected and requested to be a powerful tool to obtain diffraction data from protein micro-crystals. The light source of this beamline can easily cover the energy range of 5-18 keV and can meet the requirement of the SAD techniques based on S and Se element. It has also covered the absorption edged of most important elements, such as Cr, M, K, Xe, Cs, Ba.
This beamline is composed of the undulator source, the front end, the beamline, and the experimental station. The energy range is from 5~18 keV, the energy resolution is less than 2×10e-4 (@12keV), the Flux at sample is larger than 5×10e11 ph/s (12keV @300mA), the focused beam size is within 10×5 μm2 (H×V, @12keV), and the focused beam divergence is within 0.7×0.25 mrad2 (H×V, @12keV).
This beamline is an advanced data collection facility at NFPS/SSRF to the national user community and maintains high-profile user programs. It exploits major advances in macromolecular x-ray crystallography and addresses the most challenging structural biology problems to advance scientific knowledge. The up-to-date detector Pilatus-3-6M is equipped at this beamline. MD2 Microdiffractometer with high-speed and high-precision air bearing goniometer is used as the sample holder and sample centering system. It also equips with an automated sample changer, which makes it possible to collect data remotely. Based on the dedicated equipment, shutterless data collection method is achieved, which make it possible to collect a set of data within 1 minutes.
