Refinement of Large Small-Molecule Structures Using SHELXL-92

Many ‘mid-sized’ molecules in the 100-1000 atom range play important physiological roles, and include antibiotics, hormones and small proteins. Advances in data collection and structure-solving techniques have now effectively closed this gap between small molecules and macromolecules. Historically, quite different strategies have been adopted for the refinement of small-molecule and macromolecular structures against diffraction data. The explosion in available computing power now makes it feasible to refine structures of up to at least 1000 atoms by small-molecule techniques, though not without reconsidering the strategies involved.