[phenixbb] merohedral twinned refinement

Peter Zwart phzwart at gmail.com
Sun Jan 17 23:47:53 PST 2010

1. How do the intensity statistic look like?
2. How did you choose P3121?
3. Did you try solving and refining in P3?
4. TLS?
5. How complete is your model

2010/1/17 JXQI <jxqi at mail.im.ac.cn>:
> Dear all,
> I have a 2.3A data set processed with HKL2000. The space group is P3121 with
> 63% of solvent content and 1 molecule in the ASU. I used a 40% homology
> model to do molecular replacement. Both the Phaser and Molrep gave similar
> solution with good packing. After further refinement with phenix, the built
> model fit well with the 2mFo-DFc map. However the R/Rfree were stuck to
> 0.34/0.38.
> I rechedked the data set with xtriage and found the data set is merohedral
> twinned (with twin law"-h,-k,l", the estimated twin fraction is about 0.05).
> When I used the twin law in further refinement, the R/Rfree were only
> decreased to 0.32/0.36. Any suggestions are appreciated, thanks!
> J.X. QI
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P.H. Zwart
Beamline Scientist
Berkeley Center for Structural Biology
Lawrence Berkeley National Laboratories
1 Cyclotron Road, Berkeley, CA-94703, USA
Cell: 510 289 9246
BCSB:     http://bcsb.als.lbl.gov
PHENIX: http://www.phenix-online.org
CCTBX:  http://cctbx.sf.net

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