In the past century, diffraction, crystallography and molecular imaging have paved the way for critical breakthroughs in the fields of physics, chemistry and biology. But the dependency on crystallization has proved a significant hindrance to the structural characterization of countless un-crystallizable molecules. In the current issue of Nature, a team of over 80 researchers, 21 institutions, and 4 countries worked to conduct dual structural analysis experiments using the world's first hard X-Ray free-electron laser, the Linac Coherent Light Source (LCLS) housed at the Stanford Linear Accelerator Center. In the first of their two papers, the research team used LCLS to assess the structure of tiny protein nanoparticles, providing 3-D reconstructions at a fraction of the time necessary for crystallography studies. In the second paper, they provided the first single-shot images of intact viruses.
Previously, a complete three-dimensional reconstruction of mimivirus using cryoelectron microscopy or crystallography was unattainable because of its large size and fibrils. In this study, cooled virus particles are injected into a vacuum chamber and are randomly intercepted with LCLS pulses; far-field diffraction patterns are recorded before radiation damage occurs. Using the LCLS, they examined atomic positions of the interior and outer coat suggesting an inhomogeneous interior structure of the virion. The techniques applied did not require any sample modifications including staining, freezing, sectioning, radiolabelling or crystallization. This method is expected to revolutionize biological imaging for molecules, viruses, and live microbes.
- Vy Tran
More information on LCLS: http://www-public.slac.stanford.edu/lcls/aboutlcls.aspx