Direct Phasing of Finite Crystals Illuminated with a Free-Electron Laser

Kirian, Richard A.; Bean, Richard; Beyerlein, Kenneth R.; Barthelmeß, Miriam; Yoon, Chun Hong; Wang, Fenglin; Capotondi, Flavio; Pedersoli, Emanuele; Barty, Anton; Chapman, Henry N.

doi:10.1103/physrevx.5.011015

Cited by 17 publications

(11 citation statements)

References 52 publications

(68 reference statements)

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“…In fact, the second summation contains phase information that is targeted by new methods for directly phasing SFX data (Spence et al, 2011). In light of the progress in the direct phasing of finite crystals (Elser, 2013;Liu et al, 2014;Kirian et al, 2014Kirian et al, , 2015, it is unlikely that the second summation is entirely absent for SFX data. Here, however, our goal is to obtain an improved estimate of the structure-factor moduli jFðq k Þj by accurately modelling the first summation of equation 2cand not to pursue the additional phase information contained in the second summation term.…”

Section: General Considerationsmentioning

confidence: 99%

Whole-pattern fitting technique in serial femtosecond nanocrystallography

Dilanian

Williams

Martin

et al. 2016

Int Union Crystallogr J

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Extracting structure-factor moduli from diffraction patterns of protein nanocrystals is one of the critical issues of serial femtosecond X-ray crystallography. Unlike a conventional crystallography experiment, serial femtosecond crystallography combines data from hundreds or thousands of crystals of varying size and quality, a situation reminiscent of powder diffraction. Here the whole-pattern fitting technique, originally designed for one-dimensional powder diffraction crystallography, has been reconsidered and applied to the analysis of higher-dimensional serial femtosecond X-ray crystallography data. For nanocrystals with a small number of unit cells, the whole-pattern fitting approach is shown to be more accurate than integration-based Monte Carlo methods.

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Section: General Considerationsmentioning

confidence: 99%

Whole-pattern fitting technique in serial femtosecond nanocrystallography

Dilanian

Williams

Martin

et al. 2016

Int Union Crystallogr J

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“…Coherent diffractive imaging techniques [15,16] might then be used for the determination of the unit cell structure. This was later demonstrated with experimental data using artificial targets [17]. Other work has considered this with the inclusion of incomplete unit cells [13,[18][19][20], for which a common definition of the underlying repeating atomic structure of the crystal is no longer satisfied.…”

Section: Introductionmentioning

confidence: 99%

Analysis of Diffracted Intensities from Finite Protein Crystals with Incomplete Unit Cells

et al. 2017

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Developments in experimental techniques in micro electron diffraction and serial X-ray crystallography provide the opportunity to collect diffraction data from protein nanocrystals. Incomplete unit cells on the surfaces of protein crystals can affect the distribution of diffracted intensities for crystals with very high surface-to-volume ratios. The extraction of structure factors from diffraction data for such finite protein crystals sizes is considered here. A theoretical model for the continuous diffracted intensity distribution for data merged from finite crystals with two symmetry-related sub-units of the conventional unit cell is presented. This is used to extend a whole-pattern fitting technique to account for incomplete unit cells in the extraction of structure factor amplitudes. The accuracy of structure factor amplitudes found from this whole-pattern fitting technique and from an integration approach are evaluated.

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“…One approach for obtaining this information is based on measuring gradients around the Bragg peaks (Perutz, 1954;Elser, 2013). An alternative approach involves decoupling the unit-cell transform from the finite lattice transform (Yefanov et al, 2014;Kirian et al, 2015). The effects of disorder (particularly relevant for work on crystals at cryotemperature) can also be incorporated (Dilanian et al, 2013).…”

Section: Introductionmentioning

confidence: 99%

Imperfection and radiation damage in protein crystals studied with coherent radiation

Nave

Sutton

Evans

et al. 2016

J Synchrotron Radiat

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Fringes and speckles occur within diffraction spots when a crystal is illuminated with coherent radiation during X-ray diffraction. The additional information in these features provides insight into the imperfections in the crystal at the submicrometre scale. In addition, these features can provide more accurate intensity measurements (e.g. by model-based profile fitting), detwinning (by distinguishing the various components), phasing (by exploiting sampling of the molecular transform) and refinement (by distinguishing regions with different unit-cell parameters). In order to exploit these potential benefits, the features due to coherent diffraction have to be recorded and any change due to radiation damage properly modelled. Initial results from recording coherent diffraction at cryotemperatures from polyhedrin crystals of approximately 2 mm in size are described. These measurements allowed information about the type of crystal imperfections to be obtained at the sub-micrometre level, together with the changes due to radiation damage.

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Direct Phasing of Finite Crystals Illuminated with a Free-Electron Laser

Cited by 17 publications

References 52 publications

Whole-pattern fitting technique in serial femtosecond nanocrystallography

Whole-pattern fitting technique in serial femtosecond nanocrystallography

Analysis of Diffracted Intensities from Finite Protein Crystals with Incomplete Unit Cells

Imperfection and radiation damage in protein crystals studied with coherent radiation

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