Polder maps: improving OMIT maps by excluding bulk solvent

The crystallographic maps that are routinely used during the structure-solution workflow are almost always model-biased because model information is used for their calculation. As these maps are also used to validate the atomic models that result from model building and refinement, this constitutes an immediate problem: anything added to the model will manifest itself in the map and thus hinder the validation. OMIT maps are a common tool to verify the presence of atoms in the model. The simplest way to compute an OMIT map is to exclude the atoms in question from the structure, update the corresponding structure factors and compute a residual map. It is then expected that if these atoms are present in the…

• UD
  U.S. Department of Energy

  Awards: -AC02-05CH11231, Contract No. DE-AC02-05CH11231, 05CH11231, No. DE-AC02-05CH11231, AC02-05CH11231, DE-AC02, DE-AC02-05CH11231, DE-AC02-
• NI
  National Institutes of Health

  Awards: GM063210, 1P01 GM063210, DE-AC02-05CH11231