Welcome to a seminar given by Dr. Gleb Bourenkov from beamline P14 at EMBL. He will present their recent development of phase-contrast X-ray imaging at the macromolecular crystallography beamline P14 and its application to crystal visualization, particularly for the challenging crystals that are difficult to identify by visible light.

Venue: MAX IV Laboratory, 4th floor MAX III room

Time: Tuesday, May 14 2019, 14:00 – 15:00

Title: Visualization of protein crystals by high-energy phase-contrast X-ray imaging

Abstract:
For the extraction of the best possible X-ray diffraction data from macromolecular crystals, accurate positioning of the crystals with respect to the X-ray beam is crucial. In addition, information about the shape and internal defects of crystals allows to optimize data collection strategies. We demonstrate that the X-ray beams available on the macromolecular crystallography beamline P14 on the high-brilliance synchrotron radiation source PETRA III at DESY (Hamburg, Germany) can be used for high-energy phase-contrast micro-tomography of protein crystals mounted in an optically opaque lipidic cubic phase matrix. Three-dimensional tomograms obtained at X-ray doses that are substantially smaller and time-scales that are substantially shorter than those used for diffraction scanning approaches display protein crystals at µm-resolution. Adding a compound refractive lens as an objective to the imaging setup, two-dimensional imaging at sub-µm resolution has been achieved. All experiments were performed on a standard macromolecular crystallography beamline and are compatible with standard diffraction data collection workflows and apparatus. Phase-contrast X-ray imaging of macromolecular crystals could find wide application at existing and upcoming low-emittance synchrotron radiation sources.