Dear all, Large complexes may sometimes entail unique eccentricities. I have a few questions related to problems with these huge molecules .
The use of spherical harmonics to approximate Patterson function in the Crowther algorithm limits the size of the cut-off radius that defines intra-molecular vectors. Do you think the Fast rotation procedure of Crowther as implemented in AMORE/MOLREP should work with really big non-symmetrical complexes ? The fast rotation in Phaser also uses analogous functions. Does this also imposes some practical constraints on the size of complexes for molecular replacement with Phaser ? Could the following problem in identifying NCS arise where very large complexes are involved ? Consider a rotational non-crystallographic symmetry axis that is a few degrees short of being parallel to a crystallographic axis. Therefore no peaks are detected in Self rotation tests (right ?). No peaks that correspond to translation in native Patterson map calculated with a low-resolution limit of 12-15A or in native Patterson with normalized intensities. A peak only appears in native Patterson map calculated with low resolution limit of 30-40A or lower. Is this possible ? Would you trust native Patterson to such low resolution (assuming careful measurements of these reflections) ? I'll be grateful for your thoughts and comments, Peter Grey
