Pietro Musumeci and Jose Rodriguez from UCLA will give a joint STROBE seminar about Ultrafast Electron Diffraction of Materials and Electron Diffraction of Protein Nanocrystals.
Speaker: Pietro Musumeci
Title: High energy ultrafast electron diffraction
Abstract: In this talk I'll review the application of relativistic energy ultrashort electron beams to the direct investigation of structural changes in matter at atomic length scale with sub-ps resolution by time-resolved electron diffraction (ED). There are many benefits of using higher energy electron beams for time-resolved electron scattering instrumentation, mainly due to the space charge force suppression at relativistic energies which enables more intense and shorter electron bunches. Speed-of-light probes, higher penetration and shorter de-Broglie wavelength are other advantages associated with MeV electron energy. The use of MeV beams for electron scattering demands excellent beam quality both in the transverse and longitudinal phase spaces, i.e. an exquisitely high 6D brightness. In the last decade expertise from the low energy microscopy and diffraction community have merged with advances made in relativistic electron sources for high energy particle accelerators and 4th generation synchrotron light sources in the effort to create and deliver electron beams with these characteristics.
Speaker: Jose Rodriguez
Title: Atomic structures of mammalian prion protein nanocrystals
Abstract: The structure of prion in its infectious state remains unknown. Difficulties in crystallizing prion mirror the challenges faced in obtaining structures from other amyloid (or unstructured) proteins, which often form fibrillar aggregates. While other conventional methods for structure determination have failed, 3D electron diffraction has facilitated structure determination from a number of amyloid forming segments. Using MicroED, we have now determined structures of human prion segments in the amyloid state. Our nine residue segments originate from the beta2-alpha2 loop of human or bank vole prion, a region of the protein known for its regulation of prion transmission between species. The highly ordered nature of these crystals allows us to determine their structures ab initio and to use them as models for mapping diffraction at the nano-scale (10-20nm resolution). These structures offer a valuable cross-species comparison of prion amyloid and make a unique platform for advancing the method of electron diffraction to benefit the study of proteins and polymers.