A thought - are these molecules related by a non-crystallographic
translation involving 0.5 along any axes. In such a case it is easy to
get the space group wrong, and assign a "1 axis when it is really only a
pseudo 21. if that happends your refinement will stick..
I think that at that resolution you should keep on NCS restraints till
the model is complete, but maybe relax them once it is all built. it is
always tricky though to decide on the best protocl..
Eleanor
Daniel Bonsor wrote:
Hello again!
Following my previous question, there was something wrong with the staring model for molecular replacement. Now that is sorted, I have 8 complexes in the ASU. After a few rounds of refinement with NCS and isotropic Bfactors, both the Rfactor and Rfree get stuck at 30% and 36%, respectively.
I have only just noticed that I am trying to model ~43000 atoms with ~95000
unique reflections (98% complete, at 2.58 Angstrom resolution). Is this the
reason why the R factors are stuck and I should start the refinement again from
scratch using overall Bfactors with NCS and switch to TLS once my Rfactor is
less than 30% and possibly reduce the number of reflections used for Rfree
(currently using the standard CCP4 5%)
Any input would be greatly appreciated!
Dan
