When searching for multiple molecules/ASU, you need to be careful with how the software handles packing. Small but acceptable clashes can accumulate and cause the searches to fail. I suggest using a highly trimmed as well as a poly-alanine model. I've had success with both epmr and Phaser. With Phaser, you'll probably want to loosen the acceptable number of packing clashes.
Ho Ho Leung Ng University of Hawaii at Manoa Assistant Professor, Department of Chemistry h...@hawaii.edu On Mon, Apr 30, 2012 at 1:00 PM, CCP4BB automatic digest system <lists...@jiscmail.ac.uk> wrote: > Date: Mon, 30 Apr 2012 15:41:54 +0000 > From: "Ke, Jiyuan" <jiyuan...@vai.org> > Subject: Suggestions for solving a structure with 8-10 copies per asymmetric > unit > > Dear All, > > I have a question regarding solving a crystal structure by molecular > replacement. It is a single protein with a molecular weight of 25.5 kDa. The > cell dimension is rather big from the diffraction data ( 90.9 Å, 143.9 Å, > 216.3Å, 90°, 90°, 90°). The possible space group is P212121. With such a big > unit cell, we predicted that there are 8-10 molecules per asymmetric unit. We > have a decent model with sequence similarity of 49%. I tried several times > with Phaser search with the current model and had difficulty to find any > clear solution. Has anyone seen such cases and any suggestions to solve the > structure? Thanks! > > Jiyuan Ke, Ph.D. > Research Scientist > Van Andel Research Institute > 333 Bostwick Ave NE > Grand Rapids, MI 49503
