Exploiting X-ray induced anisotropic lattice changes to improve intensity extraction in protein powder diffraction: Application to heavy atom detection

X-ray induced anisotropic variations of cell parameters in porcine pancreatic elastase (PPE) were used in a multi-Pawley refinement in order to improve the deconvolution of overlapping peaks occurring in the high-angle region of the powder pattern. The benefit of combining scans is demonstrated by an improvement in the quality of the isomorphous difference Patterson maps used to detect the positions of heavy atoms in a uranyl derivative of PPE.