The Astbury Centre for Structural Molecular Biology
Gallery and Structures
The Astbury Society
Leeds' single crystal X-ray facility has been designated an 'International Site of Excellence' by the Molecular Structure Corporation (MSC). The facility houses three rotating anode systems, with a variety of different detectors. They are housed in an air-conditioned room (8.116) in the Astbury Biomolecular Sciences building. The room has its own closed circuit cooling water supply.
The facilities are available to external users for a fee. Users from outside Leeds University should contact the Manager to arrange data collection time.
Rigaku RU-H3R rotating anode generator, MSC confocal max-flux optics, R-axis IV++
The generator can operate up to 18kW The optics are the "blue" configuration shown to be optimal for an image plate system. The detector is an R-axis IV++ with dual 30 x 30 cm white imaging plates. Smallest pixel size is 50 x 50 micrometres. The crystal to detector distance can be varied from 70 to 450 mm. The detector is controlled by the MSC software CrystalClear, which includes the data processing software d*trek, allowing 3-D reflection profiling and integration, and thus a fine phi-slicing data collection strategy if required. The standard data processing packages MOSFLM and DENZO can also be used in-house. The system also includes an inverse phi to enable use of any length of cryo pin / loop or capillary, and allow retrieval of frozen crystals. This will be particularly advantageous for external users, as the mounting and retrieval of frozen crystals will be system non-specific. An Oxford Cryosystems series 600 cryostream is mounted on the system. There is no 2-theta arm on the system.
Rigaku RU-200 rotating anode generator, MSC / Yale mirrors, R-axis IIc
The generator is operated at 50kV, 100mA (5kW). The optics are MSC / Yale mirrors. The detector is an R-axisIIc, with dual 18 x 18 cm imaging plates. Smallest pixel size is 100 x 100 micrometres. The crystal to detector distance can be varied from 65 to 200 mm. The detector is controlled by R-axis control software. Standard data processing packages MOSFLM and DENZO can be used in-house. The phi-axis is vertical, and frozen crystal mounting and retrieval is accomplished using the 180 degree arc system from 4DX-ray Systems AB. An Oxford Cryosystems series 600 cryostream is mounted on the system. There is no 2-theta arm on the system.
Rigaku RU-200 rotating anode generator, graphite monchromator, Bruker AXSXentronics X100A multiwire area detector + Nonius precession camera
The generator is operated at 45kV, 60mA (2.7kW). The optics system is a graphite monochromator. The detector is a multiwire (detector face, 5cm radius). Smallest pixel size is 195 x 195 micometres. The crystal to detector distance can be varied from 90 to 300 mm. The detector is controlled by Xentronics control software. The standard data processing package XDS can be used in-house. A fine phi-slicing data collection strategy is used. The phi-axis is vertical, with the goniometer mount at 450. A 2-theta arm is installed on the system, allowing the detector to be displaced and enabling the collection of higher resolution data.
Crystallisation facilities, room 8.115 (Astbury)
A temperature controlled room (18C) for crystallisation is available. If the temperature of the room deviates by more than +/- 2C, then an alarm is activated at Security. Six temperature controlled crystal incubators are available for crystallisation at different temperatures. Crystallisations at 4C can be set up in the adjacent cold room. The room contains a Leica MZ6 and Leica MZ12 microscopes for examining crystals. A Nikon F3 35mm SLR camera with microscope attachment is available for taking crystal pictures.
An anaerobic glovebox (Belle Technology; http://www.belle-technology.com) for anaerobic crystallisations, solution work, and crystal manipulation, mounting and flash freezing in liquid nitrogen is available. The box consists of two compartments; a large 3 glove box, with large and small entry / exit ports, for solution work and crystallisations, and a crystal mounting and freezing box, containing a built-in Leica MZ6 microscope and liquid nitrogen port, which can be isolated from the main box
Xenon pressure cell
A xenon pressure cell for derivatisation of macromolecular crystals is available. The cell is based on a design from the MRC labs in Cambridge. Crystals are mounted in loops, so the cell is only compatible with subsequent freezing of the crystals. Xenon can be used to solve the phase problem in the same way as any other heavy atom derivative. It binds to hydrophobic sites in the molecule, and the resulting crystallographic data tends to be quite isomorphous to native (untreated) crystals. In addition xenon has an absorption edge close to the wavelength of CuKalpha radiation, so anomalous data can be collected on a home source. Current statistics from the MRC labs show that in 50% of cases xenon was a good macromolecular crystal derivative.
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