Discrimination of solvent from protein regions in native Fouriers as a means of evaluating heavy-atom solutions in the MIR and MAD methods

An automated examination of the native Fourier is tested as a means of eval uation of a heavy-atom solution in MAD and MIR methods for macromolecular c rystallography. It is found that the presence of distinct regions of high a nd low density variation in electron-density maps is a good indicator of th e correctness of a heavy-atom solution in the MIR and MAD methods. The meth od can be used to evaluate heavy-atom solutions during MAD and MIR structur e solutions and to determine the handedness of the structure if anomalous d ata have been measured.