[ccp4bb]: problem with refinement

[Zhiqiang Lu <lu@pompeii.uark.edu>]

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Dear All, 

Looking for some help here with the refinement on a small protein
structure. (does not look like CCP4 related, sorry)

I was able to fit the AA into the solvent-flipped density map from CNS -
everything looks just wonderful except for one five-residue loop. However,
shelxl refinement does not like this model, returning R(free) around 50%
at 1.8A resolution. Any suggestions, anyone? Thanks very much! 

BTW, does this have anything to do with these two facts: 1) the space
group is I432; and 2) the model is being refined against Se-Met data
without merging Friedel mates? 

Z. Lu


=====
Zhiqiang Lu,  Graduate Student
Department of Chemistry & Biochemistry
University of Arkansas
Fayetteville, AR 72701
U.S.A.