Abstract
Sample-exchange robots that can exchange cryo-pins bearing protein crystals out of experimental hutches according to user instructions have been developed. The robots were designed based on the SAM (Stanford Synchrotron Research Laboratory automated mounting) system. In order to reduce the time required for the sample exchange, the single tongs of the SAM system were modified and a double-tongs system that can hold two cryo-pins at the same time was developed. Robots with double tongs can move to the goniometer head holding the next cryo-pin with one set of tongs, dismount the experimented cryo-pin with the other set, and then mount the next pin onto the goniometer head without leaving the diffractometer area. Two different types of tongs have been installed: single tongs at beamlines BL-5A and AR-NW12A, and a double-tongs system at beamline BL-17A of the Photon Factory. The same graphical user interface software for operation of the sample-exchange robots is used at all beamlines, however, so that users do not need to consider differences between the systems. In a trial, the robot with double tongs could exchange samples within 10 s.
Highlights
Protein crystallography involves many steps: overexpression, purification, crystallization, data collection, data processing and structure determination
The advantages in insertion devices, beamline optics and fast-readout CCD detectors have substantially reduced the time required for X-ray experiments, and a major proportion of beam time is spent on sample manipulation in experimental hutches
In this paper we describe sample-exchange robots installed in our beamlines and the double-tongs system that we have developed for high-throughput operation
Summary
Protein crystallography involves many steps: overexpression, purification, crystallization, data collection, data processing and structure determination. We have already developed a high-throughput protein crystallization system (Hiraki et al, 2006), used this system to produce a large number of protein crystals, and determined their structures. We are developing an automated crystal harvesting system consisting of a micromanipulator and a six-axis industrial robot for holding cryoloops (Ohara et al, 2004). X-ray protein crystallographic experiments at synchrotron beamlines are often carried out with loop-mounted crystals under cryogenic conditions. The advantages in insertion devices, beamline optics and fast-readout CCD detectors have substantially reduced the time required for X-ray experiments, and a major proportion of beam time is spent on sample manipulation in experimental hutches. In this paper we describe sample-exchange robots installed in our beamlines and the double-tongs system that we have developed for high-throughput operation
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