X-ray diffraction from hydrated macromolecular crystals using laser-driven X-ray source

Laser-driven X-ray sources offer a compact route towards laboratory-scale ultrafast structural dynamics. However, due to the low photon flux available from laboratory scale sources, and the weak diffraction signal from biological specimens, their application to such samples remains challenging. Here, we demonstrate X-ray diffraction from Z-DNA crystals using a laser-driven Cu Ka source (lambda = 1.54 Angstroms). Crystals were grown either directly in a custom-designed sample holder, which preserved the hydrated crystallisation environment and allowed in situ diffraction measurements, or using the hanging-drop vapour-diffusion method, followed by loop mounting for diffraction measurements. Well-defined Bragg reflections extending to approximately 2.5 Angstroms resolution were recorded in 1--3 min exposures at a photon flux of approximately 2.2 x 10^5 photons/s at the sample. The acquisition time and diffraction quality compare favourably with earlier demonstrations of macromolecular crystal diffraction using laser-driven X ray sources. These results demonstrate the potential of modern compact laser-driven X-ray sources for structural studies of macromolecular crystals and provide a basis for their future application to laboratory-scale time-resolved crystallography.