Limits...
Towards phasing using high X-ray intensity.

Galli L, Son SK, Barends TR, White TA, Barty A, Botha S, Boutet S, Caleman C, Doak RB, Nanao MH, Nass K, Shoeman RL, Timneanu N, Santra R, Schlichting I, Chapman HN - IUCrJ (2015)

Bottom Line: X-ray free-electron lasers (XFELs) show great promise for macromolecular structure determination from sub-micrometre-sized crystals, using the emerging method of serial femtosecond crystallography.The extreme brightness of the XFEL radiation can multiply ionize most, if not all, atoms in a protein, causing their scattering factors to change during the pulse, with a preferential 'bleaching' of heavy atoms.A pattern sorting scheme is proposed to maximize the ionization contrast and the way in which the local electronic damage can be used for a new experimental phasing method is discussed.

View Article: PubMed Central - HTML - PubMed

Affiliation: Center for Free-Electron Laser Science, Deutsches Elektronen-Synchrotron DESY , Notkestrasse 85, Hamburg, 22607, Germany ; Department of Physics, University of Hamburg , Luruper Chaussee 149, Hamburg, 22761, Germany.

ABSTRACT
X-ray free-electron lasers (XFELs) show great promise for macromolecular structure determination from sub-micrometre-sized crystals, using the emerging method of serial femtosecond crystallography. The extreme brightness of the XFEL radiation can multiply ionize most, if not all, atoms in a protein, causing their scattering factors to change during the pulse, with a preferential 'bleaching' of heavy atoms. This paper investigates the effects of electronic damage on experimental data collected from a Gd derivative of lysozyme microcrystals at different X-ray intensities, and the degree of ionization of Gd atoms is quantified from phased difference Fourier maps. A pattern sorting scheme is proposed to maximize the ionization contrast and the way in which the local electronic damage can be used for a new experimental phasing method is discussed.

No MeSH data available.


Related in: MedlinePlus

The resulting effective scattering strength of the single Gd ion at the end of each refinement cycle.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC4645107&req=5

fig2: The resulting effective scattering strength of the single Gd ion at the end of each refinement cycle.

Mentions: Another piece of qualitative evidence of the ionization provoked by the FEL radiation comes from the and refinement. This was performed with phenix_refine (Adams et al., 2010 ▸), starting from the anomalous differences (DANO) values and the phases from the best refined model. 20 cycles of alternated real-space and refinement of the two Gd atoms were performed for the LF and HF data. Fig. 2 ▸ displays the resulting scattering strength of the single Gd ion as a function of the refinement cycle, suggesting that the ionization is higher for the HF set, with a difference of about 5 electrons.


Towards phasing using high X-ray intensity.

Galli L, Son SK, Barends TR, White TA, Barty A, Botha S, Boutet S, Caleman C, Doak RB, Nanao MH, Nass K, Shoeman RL, Timneanu N, Santra R, Schlichting I, Chapman HN - IUCrJ (2015)

The resulting effective scattering strength of the single Gd ion at the end of each refinement cycle.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4645107&req=5

fig2: The resulting effective scattering strength of the single Gd ion at the end of each refinement cycle.
Mentions: Another piece of qualitative evidence of the ionization provoked by the FEL radiation comes from the and refinement. This was performed with phenix_refine (Adams et al., 2010 ▸), starting from the anomalous differences (DANO) values and the phases from the best refined model. 20 cycles of alternated real-space and refinement of the two Gd atoms were performed for the LF and HF data. Fig. 2 ▸ displays the resulting scattering strength of the single Gd ion as a function of the refinement cycle, suggesting that the ionization is higher for the HF set, with a difference of about 5 electrons.

Bottom Line: X-ray free-electron lasers (XFELs) show great promise for macromolecular structure determination from sub-micrometre-sized crystals, using the emerging method of serial femtosecond crystallography.The extreme brightness of the XFEL radiation can multiply ionize most, if not all, atoms in a protein, causing their scattering factors to change during the pulse, with a preferential 'bleaching' of heavy atoms.A pattern sorting scheme is proposed to maximize the ionization contrast and the way in which the local electronic damage can be used for a new experimental phasing method is discussed.

View Article: PubMed Central - HTML - PubMed

Affiliation: Center for Free-Electron Laser Science, Deutsches Elektronen-Synchrotron DESY , Notkestrasse 85, Hamburg, 22607, Germany ; Department of Physics, University of Hamburg , Luruper Chaussee 149, Hamburg, 22761, Germany.

ABSTRACT
X-ray free-electron lasers (XFELs) show great promise for macromolecular structure determination from sub-micrometre-sized crystals, using the emerging method of serial femtosecond crystallography. The extreme brightness of the XFEL radiation can multiply ionize most, if not all, atoms in a protein, causing their scattering factors to change during the pulse, with a preferential 'bleaching' of heavy atoms. This paper investigates the effects of electronic damage on experimental data collected from a Gd derivative of lysozyme microcrystals at different X-ray intensities, and the degree of ionization of Gd atoms is quantified from phased difference Fourier maps. A pattern sorting scheme is proposed to maximize the ionization contrast and the way in which the local electronic damage can be used for a new experimental phasing method is discussed.

No MeSH data available.


Related in: MedlinePlus