Re-thinking the role of the beamstop at a synchrotron-based protein crystallography beamline

Alkire, R. W.; Schuessler, R.; Rotella, F. J.; Gonczy, J. D.; Rosenbaum, G.

doi:10.1107/s0021889804014499

Cited by 7 publications

(4 citation statements)

References 10 publications

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“…Cassetta et al, 1999;Fourme et al, 1999;Helliwell, 1992;Hendrickson, 1999;Pohl et al, 2001), new and improved datacollection procedures (e.g. Alkire et al, 2004;Weiss, Sicker, Djinovic Carugo et al, 2001) and novel theoretical developments implemented in user-friendly software (e.g. de La Fortelle & Bricogne, 1997;Pannu & Read, 2004;Schneider & Sheldrick, 2002;Terwilliger, 2003;Weeks & Miller, 1999).…”

Section: Introductionmentioning

confidence: 99%

Anomalous signal indicators in protein crystallography

Zwart

2005

Acta Crystallogr D Biol Crystallogr

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A Monte Carlo procedure is described that generates random structure factors with simulated errors corresponding to an X-ray data set of a protein of a specific size and given heavy-atom content. The simulated data set can be used to estimate Bijvoet ratios and figures of merit as obtained from SAD phasing routines and can be used to gauge the feasibility of solving a structure via the SAD method. In addition to being able to estimate results from phasing, the simulation allows the estimation of the correlation coefficient between |DeltaF|, the absolute Bijvoet amplitude difference, and FA, the structure-factor amplitude of the heavy-atom model. As this quantity is used in various substructure-solution routines, the estimate provides a rough estimate of the ease of substructure solution. Furthermore, the Monte Carlo procedure provides an easy way of estimating the number of significant Bijvoet intensity differences, denoted as the measurability, and is proposed as an intuitive measure of the quality of anomalous data.

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Section: Introductionmentioning

confidence: 99%

Anomalous signal indicators in protein crystallography

Zwart

2005

Acta Crystallogr D Biol Crystallogr

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“…Neutrons striking cadmium produce high-energy radiation; the local radiation field can be reduced by preceding the cadmium with neutron-absorbing material such as 6 Li-rubber or boron-impregnated material, slightly offset from the slit edges. For X-rays, centring-slit design and materials should take into consideration slit shape, stopping power, fluorescence and scattering effects (Libbert et al, 1997;Vlieg et al, 1997;Le Bolloc'h et al, 2002;Alkire et al, 2004).…”

Section: Step A: Mounting a Pre-sample Slit On A Linear Translatormentioning

confidence: 99%

Total-scattering-based automatic centring of capillary samples within powder diffractometers

Cranswick¹,

Donaberger²

2008

J Appl Cryst

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A computer‐controlled method for the automatic mechanical centring of a powder capillary sample onto the rotation centre of a powder diffractometer, using total scattering of the radiation beam into one‐dimensional or two‐dimensional detectors, and only a 90° rotation of the sample stage, is described. This method is particularly useful for situations where powder capillaries are within non‐ambient experimental apparatus or loaded via an automatic sample changer. Irregularly shaped samples, potentially subject to absorption effects, are aligned and centred on the sample's `scattering centre'.

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“…A composite beam stop, designed and fabricated locally (Alkire, Schuessler et al, 2004), protects the CCD detector (see below) from exposure to the direct X-ray beam. The beam stop was made out of a 100 mm Â 12 mm Â 1 mm-thick tungsten plate with a 0.5 mm-diameter Â 2 mm-deep cavity machined into the end of the plate to intercept the direct beam.…”

Section: Beam Stopmentioning

confidence: 99%

The Structural Biology Center 19ID undulator beamline: facility specifications and protein crystallographic results

et al. 2005

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The 19ID undulator beamline of the Structure Biology Center has been designed and built to take full advantage of the high flux, brilliance and quality of X-ray beams delivered by the Advanced Photon Source. The beamline optics are capable of delivering monochromatic X-rays with photon energies from 3.5 to 20 keV (3.5-0.6 A wavelength) with fluxes up to 8-18 x 10(12) photons s(-1) (depending on photon energy) onto cryogenically cooled crystal samples. The size of the beam (full width at half-maximum) at the sample position can be varied from 2.2 mm x 1.0 mm (horizontal x vertical, unfocused) to 0.083 mm x 0.020 mm in its fully focused configuration. Specimen-to-detector distances of between 100 mm and 1500 mm can be used. The high flexibility, inherent in the design of the optics, coupled with a kappa-geometry goniometer and beamline control software allows optimal strategies to be adopted in protein crystallographic experiments, thus maximizing the chances of their success. A large-area mosaic 3 x 3 CCD detector allows high-quality diffraction data to be measured rapidly to the crystal diffraction limits. The beamline layout and the X-ray optical and endstation components are described in detail, and the results of representative crystallographic experiments are presented.

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Re-thinking the role of the beamstop at a synchrotron-based protein crystallography beamline

Cited by 7 publications

References 10 publications

Anomalous signal indicators in protein crystallography

Anomalous signal indicators in protein crystallography

Total-scattering-based automatic centring of capillary samples within powder diffractometers

The Structural Biology Center 19ID undulator beamline: facility specifications and protein crystallographic results

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