Angles flip
angles_flip
Parameters
- selection=string
- (default: none)
Description
The angles flip command can be used to optimally flip torsion angles that have two equivalent positions differing by 180 degrees in a group on conformers. Such flipping is useful, for instance, when calculating RMSD values. In polypeptides this applies mainly to the aromatic rings of Phe and Tyr (CHI2), and to the side-chain COO- groups of Asp (CHI2) and Glu (CHI3).
Torsion angles that match the selection string are changed by 180 degrees, if necessary to attain the smallest possible deviation from a common average value within the selected conformers. By default, the selection made in the most recent angles select command is used, or all angles if no selection has been made so far. Flipping will occur only for those selected torsion angles that have two equivalent positions differing by 180 degrees.
The flip.cya macro provides a convenient interface for appying this command to proteins.