Analysis of polycrystallinity in hen egg-white lysozyme using a pnCCD

A crystal of hen egg‐white lysozyme was analyzed by means of energy‐dispersive X‐ray Laue diffraction with white synchrotron radiation at 2.7 Å resolution using a pnCCD detector. From Laue spots measured in a single exposure of the arbitrarily oriented crystal, the lattice constants of the tetragonal unit cell could be extracted with an accuracy of about 2.5%. Scanning across the sample surface, Laue images with split reflections were recorded at various positions. The corresponding diffraction patterns were generated by two crystalline domains with a tilt of about 1° relative to each other. The obtained results demonstrate the potential of the pnCCD for fast X‐ray screening of crystals of macromolecules or proteins prior to conventional X‐ray structure analysis. The described experiment can be automatized to quantitatively characterize imperfect single crystals or polycrystals.