Automated sample mounting and alignment system for biological crystallography at a synchrotron source.

High-throughput data collection for macromolecular crystallography requires an automated sample mounting and alignment system for cryo-protected crystals that functions reliably when integrated into protein-crystallography beamlines at synchrotrons. Rapid mounting and dismounting of the samples increases the efficiency of the crystal screening and data collection processes, where many crystals can be tested for the quality of diffraction. The sample-mounting subsystem has random access to 112 samples, stored under liquid nitrogen. Results of extensive tests regarding the performance and reliability of the system are presented. To further increase throughput, we have also developed a sample transport/storage system based on "puck-shaped" cassettes, which can hold sixteen samples each. Seven cassettes fit into a standard dry shipping Dewar. The capabilities of a robotic crystal mounting and alignment system with instrumentation control software and a relational database allows for automated screening and data collection to be developed.

Advanced beamline automation for biological crystallography experiments.

An automated crystal-mounting/alignment system has been developed at Lawrence Berkeley National Laboratory and has been installed on three of the protein-crystallography experimental stations at the Advanced Light Source (ALS); it is currently being implemented at synchrotron crystallography beamlines at CHESS, NSLS and the APS. The benefits to using an automounter system include (i) optimization of the use of synchrotron beam time, (ii) facilitation of advanced data-collection techniques, (iii) collection of higher quality data, (iv) reduction of the risk to crystals and (v) exploration of systematic studies of experimental protocols. Developments on the next-generation automounter with improvements in robustness, automated alignment and sample tracking are under way, with an end-to-end data-flow process being developed to allow remote data collection and monitoring.

Suite of three protein crystallography beamlines with single superconducting bend magnet as the source.

At the Advanced Light Source, three protein crystallography beamlines have been built that use as a source one of the three 6 T single-pole superconducting bending magnets (superbends) that were recently installed in the ring. The use of such single-pole superconducting bend magnets enables the development of a hard X-ray program on a relatively low-energy 1.9 GeV ring without taking up insertion-device straight sections. The source is of relatively low power but, owing to the small electron beam emittance, it has high brightness. X-ray optics are required to preserve the brightness and to match the illumination requirements for protein crystallography. This was achieved by means of a collimating premirror bent to a plane parabola, a double-crystal monochromator followed by a toroidal mirror that focuses in the horizontal direction with a 2:1 demagnification. This optical arrangement partially balances aberrations from the collimating and toroidal mirrors such that a tight focused spot size is achieved. The optical properties of the beamline are an excellent match to those required by the small protein crystals that are typically measured. The design and performance of these new beamlines are described.