ACTOR: automated crystal transport, orientation and retrieval

Abstract

A high-throughput, general purpose robotic system has been developed which transports flash-cooled crystals securely and safely, automatically mounts crystals on most goniometers, optically centers them in the x-ray beam, screens for diffraction quality, collects and processes diffraction images, recovers the crystals and stores them in a liquid nitrogen dewar. The system is a refinement of the proven actor system from abbott laboratories [1]. Magnetic crystal storage and transport magazines are designed to hold up to 60 crystals in a standard dry shipper with easy access to any of the positions. The system is based on a general purpose 5-axis programmable robot that allows the system to be used in an infinite number of configurations including horizontal, vertical or virtually any other goniometer axis orientation. The unique non-magnetic end-effector securely grips standard hampton pins and places them on a ìglide goniometer magnet without the need to move cryosystream nozzles or beam stops. The ìglide goniometer translates the crystal ± 3 mm in all directions in as little as 2 micron increments for centering. All operations are controlled by director, a software tool which totally automates the high-throughput process of selection, centering, screening, collection and retrieval of crystals. The entire procedure has been optimized for high-throughput crystallography at synchrotron beamlines and in the home lab. References [1] Muchmore, S.W., Olson, J., Jones, R., Pan, J., Blum, M., Greer, J., Merrick, S.M., Magdalinos, P., & Nienaber, V. (2000) Structure 8, R243-R246. Bruker introduced lens-coupled CCD detectors two years ago. Since then we have reported on their use for macromolecular crystallography. However small molecule crystallographers have become interested in these devices, particularly because of their active area. At ALS, for example the large area (300 mm diameter) allows for positioning the detector at 2θ = 0 and collecting high resolution data most efficiently. This is despite the bending magnet source spectrum limitation of high flux at 14 KeV, or lower, i.e. longer wavelength than Mo Kα. Calibration of these detectors will be discussed and example of data collection will be given. The Canadian Light Source (CLS), a third-generation 2.9 GEV synchrotron light source, is currently under construction. The protein crystallography beamline is one of the seven beamlines to be constructed initially (of 35 beamlines at total capacity). The CMCF is planned to be a 50 m long undulator beamline to facilitate studying small crystals (approx. 50 mm) and crystals with large unit cells (approx. 1000 angstroms). Mad phasing will be one of the major applications of the beamline. Spectral range: 6.5 kev -18 kev (1.91 -0.69 angstroms), calculated flux at 12 kev (1.0 angstrom), approx. 1 x E14 ph/s/0.1/percent/bw and the focused spot size at the sample (horizontal x vertical) 0.15 mm x 0.05 mm (fwhm) generated from the 7th harmonic. Advanced user interface and control software, together with fully automated robotic...