Dear Dipankar,
Molrep Rfactors around 50% with a model with 100%
identity means that something went wrong and you did not find the solution. To
find the problem, I would proceed as follows:
1) check the processing of the data and the space
group: Are the statistics of the processing ok? Did you let the processing
software find the space group, or did you specify it? The true space group maybe
different from what you think. You may also process in P1 and let pointless
figure out the space group.
2) check that you used the correct search model. It
maybe trivial but if you mixed up pdb files, you will never find a
solution.
3) run Molrep of Phaser with the option to test all
possible spacegroups for your crystal system. During processing it is not always
possible to reliable distuinguish e.g. between P212121, P21212, P2221 etc. The
only way to find out is to systematically try all possibilities. All molecular
replacement programs do have an option for this.
4) It may also be to you searched for too many or too
few molecules. Do separate searches for 1 to as many molecules as fit
in the asymmetric unit. It is not common but crystals exist with only 30%
solvent or as much as 70% solvent.
5) Finally, try to find an experienced crystallographer
to help you. Again, your problem is not with the refinement, but with the
molecular replacement.
Good luck!
Herma
Dear Crystallographers,
Can anybody guide me how to reduce R-factor, means which
are the basic parameters I have to look for to reduce the R-factor during
refinement. I am newly learning the refinement. After running molrep R-factor
is around 53% (100% identity), after rigid body refinement its showing around
49% and after restrained refinement its showing around 47%. Highest resolution
is 2.5A.
Regards
Dipankar
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