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Acta Crystallogr D Biol Crystallogr. 2013 Jul;69(Pt 7):1223-30. doi: 10.1107/S0907444913009700. Epub 2013 Jun 15.

A Medipix quantum area detector allows rotation electron diffraction data collection from submicrometre three-dimensional protein crystals.

Author information

1
Biophysical Structural Chemistry, Leiden University, Einsteinweg 55, 2333 CC Leiden, The Netherlands.

Abstract

When protein crystals are submicrometre-sized, X-ray radiation damage precludes conventional diffraction data collection. For crystals that are of the order of 100 nm in size, at best only single-shot diffraction patterns can be collected and rotation data collection has not been possible, irrespective of the diffraction technique used. Here, it is shown that at a very low electron dose (at most 0.1 e(-) Å(-2)), a Medipix2 quantum area detector is sufficiently sensitive to allow the collection of a 30-frame rotation series of 200 keV electron-diffraction data from a single ∼100 nm thick protein crystal. A highly parallel 200 keV electron beam (λ = 0.025 Å) allowed observation of the curvature of the Ewald sphere at low resolution, indicating a combined mosaic spread/beam divergence of at most 0.4°. This result shows that volumes of crystal with low mosaicity can be pinpointed in electron diffraction. It is also shown that strategies and data-analysis software (MOSFLM and SCALA) from X-ray protein crystallography can be used in principle for analysing electron-diffraction data from three-dimensional nanocrystals of proteins.

KEYWORDS:

MOSFLM; Medipix2; electron diffraction; electron microscopy; nanocrystals

PMID:
23793148
PMCID:
PMC3689525
DOI:
10.1107/S0907444913009700
[Indexed for MEDLINE]
Free PMC Article

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