GM/CA canted undulator beamlines for protein crystallography

Fischetti, Robert F.; Степанов, С. А.; Xu, Shenglan; Макаров, О. А.; Urakhchin, A.; Sanishvili, Ruslan; Smith, W.W.; Yoder, Derek W.; Benn, R.; Corcoran, Stephen; Devarapalli, Satish; Diete, W.; Schwoerer-Boehing, M.; Signorato, Riccardo; Berman, Lazar; Smith, James L.

doi:10.1107/s0108767305094110

Cited by 4 publications

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“…The radiation damage experiments were performed on beamline 23-ID-B of the Advanced Photon Source, Argonne National Laboratory (33). The wide range of beam sizes required two different optical configurations (Fig.…”

Section: Methodsmentioning

confidence: 99%

Radiation damage in protein crystals is reduced with a micron-sized X-ray beam

Sanishvili

Yoder

Pothineni

et al. 2011

Proc. Natl. Acad. Sci. U.S.A.

124

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Radiation damage is a major limitation in crystallography of biological macromolecules, even for cryocooled samples, and is particularly acute in microdiffraction. For the X-ray energies most commonly used for protein crystallography at synchrotron sources, photoelectrons are the predominant source of radiation damage. If the beam size is small relative to the photoelectron path length, then the photoelectron may escape the beam footprint, resulting in less damage in the illuminated volume. Thus, it may be possible to exploit this phenomenon to reduce radiation-induced damage during data measurement for techniques such as diffraction, spectroscopy, and imaging that use X-rays to probe both crystalline and noncrystalline biological samples. In a systematic and direct experimental demonstration of reduced radiation damage in protein crystals with small beams, damage was measured as a function of micron-sized X-ray beams of decreasing dimensions. The damage rate normalized for dose was reduced by a factor of three from the largest (15.6 μm) to the smallest (0.84 μm) X-ray beam used. Radiation-induced damage to protein crystals was also mapped parallel and perpendicular to the polarization direction of an incident 1-μm X-ray beam. Damage was greatest at the beam center and decreased monotonically to zero at a distance of about 4 μm, establishing the range of photoelectrons. The observed damage is less anisotropic than photoelectron emission probability, consistent with photoelectron trajectory simulations. These experimental results provide the basis for data collection protocols to mitigate with micron-sized X-ray beams the effects of radiation damage.microcrystallography | synchrotron radiation T he brilliance of synchrotron radiation from undulator devices on third-generation sources has been an enormous boon to crystallography of biological macromolecules. The high flux density and low divergence of undulator beams led to a rapid decrease in the minimum crystal size and minimum beam size that can yield usable diffraction data (1-4). However, the resulting decrease in diffracting volume necessitates an increase in X-ray exposure per unit sample volume, increasing radiation damage and severely compromising the substantial benefits of brilliant undulator sources. Thus, there is considerable interest in understanding the mechanism and spatial extent of X-rayinduced damage to crystals of biological macromolecules.Diffraction experiments are typically performed at cryotemperatures (approximately 100 K) to prevent the diffusion of free radicals, which are a major source of damage in crystals exposed to X-rays at higher temperatures (5), but cryocooling does not eliminate X-ray damage. Many experimental approaches to circumventing the effects of radiation damage have been investigated (6-10) but have not yet yielded a breakthrough result. Zero-dose diffraction intensities have been extrapolated from measured values by mathematical modeling (7-9). The effects of radiation damage have also been exploited for crystallograp...

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Section: Methodsmentioning

confidence: 99%

Radiation damage in protein crystals is reduced with a micron-sized X-ray beam

Sanishvili

Yoder

Pothineni

et al. 2011

Proc. Natl. Acad. Sci. U.S.A.

124

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“…These types of systems are often mandatory in large scientific facilities because of the need for a unique control room, or the impossibility, owing to safety aspects, of having a control machine inside the experiment room (McPhillips et al, 2002;Gaponov et al, 2004;Quintana, 1998;Latimer et al, 2005;Fischetti et al, 2005). Moreover, remote control could be used to minimize travel time and expenses for the users of large research facilities, allowing them to perform the experiment remotely.…”

Section: Introductionmentioning

confidence: 99%

DiXP: a Python-based GUI for controlling a powder diffractometerviathe Internet

Izaola

Madariaga

2008

J Appl Cryst

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DiXP is a multi-platform data collection program decoupled from low-level basic hardware management and based on the idea of client/server remote control. The main function of DiXP is the sequential coordination of those basic operations, allowing different strategies for the collection, archiving and graphical representation of measured data. DiXP and the control software reside, in general, on different computers and communicate with one another via the Internet using TCP sockets. The disconnection between low-level handling and the measurement process makes DiXP of general use for controlling a twocircle diffractometer, and this approach can be easily extended to more complex goniometers.

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