Synchrotron X-ray reciprocal-space mapping, topography and diffraction resolution studies of macromolecular crystal quality

A comprehensive study of microgravity and ground-grown chicken egg-white ly sozyme crystals is presented using synchrotron X-ray reciprocal-space mappi ng, topography techniques and diffraction resolution. Microgravity crystals displayed reduced intrinsic mosaicities on average, but no differences in terms of strain over their ground-grown counterparts. Topographic analysis revealed that in the microgravity case the majority of the crystal was cont ributing to the peak of the reflection at the appropriate Bragg angle. In t he ground-control case only a small volume of the crystal contributed to th e intensity at the diffraction peak. The techniques prove to be highly comp lementary, with the reciprocal-space mapping providing a quantitative measu re of the crystal mosaicity and strain (or variation in lattice spacing) an d the topography providing a qualitative overall assessment of the crystal in terms of its X-ray diffraction properties. Structural data collection wa s also carried out at the synchrotron.