There are reasons why MR might fail to find additional copies; perhaps a
surface loop in the search model interferes with packing. You should
probably take a look at solvent content.
On 11/30/2016 12:20 PM, Matthew Bratkowski wrote:
Hello all,
I am working on a structure in space group P4 at a resolution of about
4 angstrom. Xtriage indicates that translational NCS is present. I
am able to solve the structure by molecular replacement with four
copies in the asymmetric unit, and there are two sets of identical
copies. However, discontinuous, unfilled Fo-Fc density is present that
appears to correspond to additional copies of the protein in the
crystal packing. I tried having phaser search for additional
components in the ASU, but in each case the molecular replacement fails.
Is it possible that disordered copies of the protein appear in the ASU
that is accounting for the unfilled density? Other than the
additional density, the structure looks ok. I did not have too many
problems with refinement as I was able to get a final Rwork/Rfree of
around 0.24/0.29, which seems pretty decent considering the low
resolution.
Any suggestions would be helpful.
Thanks,
Matt
--
=======================================================================
All Things Serve the Beam
=======================================================================
David J. Schuller
modern man in a post-modern world
MacCHESS, Cornell University
schul...@cornell.edu
