The transformation matrix describing the symmetry is sensitive to the coordinate system origin. You should center the entire tetramer on the origin (0, 0, 0), where the origin coincides with the point symmetry element. If you have a tetramer with true point symmetry, then the center of the tetramer should be the center of mass. Then you can use lsq-expl from O or whatever the equivalent is in pymol, phenix, or coot to get the transformation matrix between any two monomers.
Repeated application of that transformation matrix to any monomer of the tetramer should generate the tetramer. James On Jan 10, 2013, at 5:48 PM, james09 pruza wrote: > Hi, > > Which program outputs the symmetry operator (rotation and translation)? I > have a dimer in the asymmetric unit and need to know the symmetry operator to > get a tetramer, the active molecule. > James >
