Restrained anisotropic refinement with<i>SHELXL</i>

Sessions3 1 corrected rather easily by changing the residue name, deleting surplus atoms or editing the LINK or CONECT records.Other problems, however, require more sophisticated methods to fix them.To fix e.g.stereochemistry problems, atoms have to be relocated.In some instances, e.g. when wrong stereochemistry is involved in glycosidic linkages, entire residues might have to be rearranged, which involves refinement of the 3d structure.Here, we present an approach to combine a tool for carbohydrate validation (pdb-care [3], www.glycosciences.de/tools/pdb-care/) with the modeling software WHAT IF [4] (swift.cmbi.ru.nl/whatif/) and the refinement tool PDB-redo [5] (www.cmbi.ru.nl/pdb_redo/) to enable a (semi-)automatic correction of erroneous carbohydrate structures in PDB entries.