Henry Chapman

Title

Imaging Proteins with X-ray Free-Electron Laser Pulses

Abstract

The ultrafast pulses from X-ray free-electron lasers (FELs) are of high enough intensity and of sufficiently short duration that individual single-shot diffraction patterns can be obtained from a sample before significant damage occurs at the atomic scale. We have applied this “diffraction before destruction” method to determine the molecular structures of proteins that cannot be grown into large enough crystals or are too radiation sensitive for conventional X-ray crystallography. Using the Linac Coherent Light Source, the world’s first hard X-ray FEL, we recorded millions of diffraction patterns from a flowing stream of protein nanocrystals of the photosystem I complex and other proteins. Our measurements show that sample destruction at high resolution can be avoided with pulses of 30 fs or shorter. We aim to push this technique to smaller and smaller samples – all the way down to the single molecule.