The variety of X-ray diffuse scattering from macromolecular crystals and its respective components

Abstract

A range of protein single-crystal diffraction patterns, recorded with intense collimated synchrotron Xradiation are presented. These patterns illustrate the rich and varied nature of the diffuse scattering from this kind of crystal and suggest that the continuous background diffraction will be a source of specific information on the molecular dynamics and flexibility of particular proteins. The relative contributions of the background X-ray diffuse scattering from the solvent, the glass capillary and the sample have been quantified for two of the samples; the so-called solvent ring is shown to be due principally to protein disorder in the crystal both because of the intensity and the marked anisotropy of the ring in specific cases. The form of the acoustic scattering associated with the Bragg peaks was studied in ribonuclease, and is shown, at low resolution at least, to be explained in terms of single-phonon interactions.