Re: [ccp4bb]: R32 pseudotranslational symmetry in crystal

[Christopher Colbert <colbc@chop.swmed.edu>]

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Hi Manoj,

Not to beat a dead horse, but have you ruled out twinning?  I had an R3
molecular replacement that did essentially the same.  Loop density was
poor and refinement was stuck in the forties with maps that said it
shouldn't be so.  Take a good look at your data just to be sure.

Good luck,

Chris

On Tue, 25 Feb 2003, N.Manoj wrote:

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>
>Dear all,
>          We have a problem in refining a structure in space group R32.
>The data processed to 2.9A with  overall Rmerge of 5%, 98% completeness
>and redundancy of 5. AMoRe gave clear solutions for the two expected
>molecules in the asymmetric unit. The packing looked good,  but the
>structure could not be refined below 45% R-factor. Electron density for
>one monomer is good while it is very poor for the other monomer. 
>The two molecules are identical (same rotation function values) in
>orientation and are translated by almost 1/2 along the Z axis. I would
>like to know if there is some way of going about refining this
>structure.   
>I remember some discussion about refinement of structures with  pseudo
>translational symmetry in the ccp4 BB some time back.
>
>Thanks in advance
>manoj
>

Christopher L. Colbert, Ph.D.
Research Associate
Howard Hughes Medical Institute                   Phone: (214) 648 5002
University of Texas Southwestern Medical Center	  FAX:   (214) 648 5095
5323 Harry Hines Boulevard
Dallas, TX 75390