The structure is partially known.
The protein molecules distinguish themselves as relatively high regions of electron density and their boundaries can be estimated. The electron density between them is then set to a constant value.
Noncrystallographic symmetry within the asymmetric unit is present and is known from molecular replacement. As in 2, molecular boundaries must then be determined and the solvent region set to a constant value. Moreover, the density of all molecules (or subunits of a molecule) related by noncrystallographic symmetry is averaged.
KeywordsPhase Angle Phase Information Density Modification Phase Improvement Solvent Region
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