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| 27/09/2005
- FOX2D CU 25_25P a new tool for small crystals
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The analysis of small crystals on home lab machines remains an important challenge and has pushed us to develop an optics designed and adapted to boost the performance of common x-ray generators: the FOX2D CU 25_25P. The figure of merit for such a system is a maximum of flux density in the focal spot together with a low background level. Taking into account the higher source size acceptance of the mirror, the higher efficiency of the single-reflection concept, and the 1:1 imaging of the source, this yields a significant increase of the flux density compared to double reflection optics. |
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A full dataset using the FOX2D CU 25_25P mirrors was collected at MRC Cambridge by Dr Andrew Leslie from a small cryo-cooled crystal of IP3-3 kinase, supplied by Dr Beatriz Gonzalez-Perez. These mirrors were then exchanged for traditional double reflection multilayer mirrors (side-by-side geometry) and a second dataset was collected from the same crystal under identical experimental conditions. The generator was an MSC/Rigaku RuH3R running at 50kV, 100mA (300 m focus) and the data were collected on a Mar345 image plate detector. The crystal was a thin plate with approximate dimensions 200x75x50m. The crystal belongs to space group C222 with cell dimensions a=72Å, b=97Å, c=191Å. The merging statistics for the two datasets are listed in the table above.
In both cases the standard deviation estimates from MOSFLM were adjusted in SCALA to reflect the true discrepancies between symmetry related reflections.
The results for the highest resolution shell show an improvement in signal to noise by a factor of 1.64. This is consistent with the average scale factor of 2.43 between the two datasets, which provides a good estimate of the relative X-ray flux hitting the crystal. If the data quality is determined solely by counting statistics, an increase in flux by a factor of 2.43 would give a factor of sqrt(2.43) = 1.56 in the signal to noise. Use of the Xenocs mirrors provides a clear improvement in data quality for this relatively small crystal.
To get more information please have a look at the complete application note at MRC Laboratory of Molecular Biology, Cambridge.
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 03/03/2008 - NEW DISTRIBUTOR IN THE USA
23/03/2007 - GeniX successfully tested at Marresearch for protein crystallography
30/10/2006 - XENOCS receives ISO 9001 certification
16/06/2006 - GeniX beam delivery system
09/03/2006 - Decreasing the size of analysed crystals with FOX2D CU 25_25P
27/09/2005 - FOX2D CU 25_25P a new tool for small crystals
15/06/2005 - FOX2D optics on a synchrotron beamline
01/03/2004 - Protein Crystallography at EMBL test site
01/11/2003 - Space research : ESA signs a contract with XENOCS
01/10/2003 - The Scripps Research Institute boosts its screening capacities
17/03/2003 - Xenocs installs its new confocal optics at EMBL in Heidelberg
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