Electron diffraction

Our aim is to develop electron crystallography for three-dimensional structure determination of proteins and, more generally, radiation sensitive macromolecules. This technique allows the use of nanoscale crystals and can provide information on the charge states of ions present in the proteins. The Tecnai F20 cryo-electron microscope at the IBS electron microscopy platform has been equipped with a 512x512 pixel Medipix3RX hybrid pixel detector from Amsterdam Scientific Instruments (ASI) since July 2020.

TF20 microscope equipped with a 512x512 pixel Medipix3RX hybrid pixel detector from Amsterdam Scientific Instruments (ASI)

This detector is very sensitive to electrons (DQE(0) > 0.9), almost noise-free, has a very high dynamic range and can acquire up to 2000 images per second, with no dead time between images. In addition, thanks to its 300 µm thick silicon window, it can be used without beam-stopper, without damaging the detector.
Diffraction data acquisition is done in continuous rotation, at room temperature as well as at liquid nitrogen temperature, and can be performed at very low electron doses to preserve the sample as much as possible. ASI’s DEXTER software or SerialEM are used to control the detector and the microscope.

  • Vitrified lysozyme crystals
  • Coulomb potential map reconstructed from 2.9 Å resolution data collected on lysozyme crystals
    Données de diffraction électronique collectées à l’IBS, à 100 K

Complete data up to 2.9Å resolution have already been collected on different lysozyme crystals and data at 0.9Å resolution have been collected on peptides and other small molecules.

Coulomb potential map reconstructed from 0.9Å resolution data collected on crystals of peptide LGNY
Données de diffraction électronique collectées à l’IBS, à température ambiante

A collaboration is underway with the Néel Institute to study metal-organic frameworks (MOFs), which are very sensitive to radiation damage.
New approaches for the preparation of protein crystals, using CEMOVIS or cryo-FIB-SEM are under development.

If you have protein crystals of a few hundred nanometers, please contact us!

(The Medipix3RX detector was partly financed by the sale of the POLARA cryo-microscope (FEI, The Netherlands) of the IBS electron microscopy facility and also thanks to a contribution from ILL)

Publication :
Blum, T., Housset, D., Clabbers, M., van Genderen, E., Bacia-Verloop, M., Zander, U., McCarthy, A., Schoehn, G., Ling, W.L.* and Abrahams, J. P.
“Statistically correcting dynamical electron scattering improves refinement of protein nanocrystals, including charge refinement of coordinated metals.”
Acta Crystallographica Section D : Structural Biology 77, Part 1, 75-85 (2021)