Unfortunately, refinement with the distance restraints is more susceptible to global effects on protein structure such as oligomerization, ligand binding, and protein-protein interactions. As an example, refinement of TR699 (PDB ID: 4KT7) was unsuccessful with the distance restraints (Figure ). A βturn was misplaced after the refinement as it was not stable by itself (Figure ). It turned out that the structure forms a dimer, and the β-turn is at the binding interface with significant interactions. The structure changed significantly because there was no restraint or significant energy barrier for preventing it. On the other hand, in this case, refinement with the Cartesian restraints were the better choice as they largely preserved the initial model as the global restraints prevented the β-turn from moving freely. We note that when we refined the model as dimer, the model could be refined using any types of restraints without losing the β-turn conformation (Figure ). However, in practical applications, reliable inference of the oligomerization state, ligand binding, or protein-protein interactions is often not possible.