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Chapter 6: Characterizing a Crystal From an Initial Native Dataset


    Michael R. Sawaya


    Methods are presented for characterizing a crystal given an initial X-ray diffraction dataset. These methods can facilitate the structure determination process and illuminate the oligomeric state and symmetry of your molecule before the crystal structure is determined. Specifically, these methods include (1) calculation of Matthews coefficient to estimate the number of molecules in the asymmetric unit; (2) calculation and interpretation of a self-rotation function to evaluate the point group symmetry of the crystallized oligomer, if contained in the crystal; (3) calculation and interpretation of a native Patterson map to evaluate the presence of noncrystallographic translational symmetry; and (4) calculation of statistics to evaluate the possibility of merohedral twinning in a crystal.