We are pleased to announce that the micro/nanofocus macromolecular crystallography beamline VMXm is now accepting applications for use of commissioning beamtime. During this period beamline staff will be working to optimize the performance of VMXm and will work closely with users to obtain the best possible results from user samples within the current operating envelope.
VMXm enables data collection from crystals smaller than 1 µm in size. We can currently cater for crystals in the range 2-10 µm in size (smallest dimension). We provide a variable beam size from 0.4 x 1.3 to 9 x 13 µm (V x H) with fully tunable energy (10 to 22 keV currently available). Data collection can be performed using either an Eiger2X 9M CdTe (high X-ray energies) and a Pilatus3 6M (medium X-ray energies).
Samples must be prepared on TEM grids and mounted on special holders that the beamline staff can provide. For this round of commissioning access, we recommend that users work closely with beamline staff in the preparation of samples and use the beamline sample preparation lab that contains a Leica GP2 plunge freezing instrument and cryo-equipped SEM for sample characterization.
VMXm is a micro/nanofocus Macromolecular Crystallography (MX) beamline aimed at atomic structure determination in cases where the production of significant quantities of protein material and/or large enough crystals is problematic. Indeed this is the case for many challenging protein complexes, membrane proteins and medically important macromolecules that yield only very small crystals.
The X-ray beam size on VMXm can be less than 0.5 microns and with the use of novel X-ray optics and electron beam imaging methods we will be able to precisely align the tiniest protein crystals into this X-ray beam, in vacuo, and measure X-ray diffraction data from them.
The ability to tune the X-ray energy allows us to exploit photoelectron escape within microcrystals at higher energies. With the CdTe Eiger detector the quantum efficiency is also improved at higher energies . These two factors lead to prolonged lifetime of crystals in the beam and gives the potential to collect data off fewer crystals.
In many ways VMXm will be a hybrid X-ray/cryoEM instrument making use of methods for sample preparation from cryo-electron-microscopy, imaging from scanning electron microscopy and diffraction data collection methods from X-ray crystallography.
First users on VMXm, from left to right: Gwyndaf Evans (Principal Beamline Scientist), Jose Trincao (Senior Beamline Scientist), Anna Warren (Senior Beamline Scientist), Emma Beale (Postdoctoral Research Associate), Ivo Tews (University of Southampton) and Rachel Bolton (University of Southampton).
Some key points about VMXm:
|Currently Available||Future Developments|
|Typical Crystal Sizes||2 - 10 microns|
|Vertical beam size||0.4 - 9 microns||0.3 - 10 microns|
|Horizontal beam size||1.3 - 13 microns||0.5 - 13 microns|
|X-ray energy range||10.0 - 22.0 keV||7.0 - 28.0 keV|
|Wavelength range||0.56 - 1.24 Å||0.44 - 1.77 Å|
Eiger2X 9M with 750 µm CdTe sensor
(used for high X-ray energies)
Pilatus3 6M with 1000 µm Si sensor
(used for medium X-ray energies)
|Fluorescence edge scans||X|
|Online integrated SEM imaging||X|
|Online integrated SEM centring||X|
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