[phenixbb] twinning detection

Keller, Jacob kellerj at janelia.hhmi.org
Mon Jun 6 13:57:14 PDT 2016

If I were you, I would proceed to whatever refinement you can do, then re-evaluate twinning. At such low resolution, however, things might be hard! Is the MR solution in the PG 3 or 32? Are the PG 32 spacegroups large enough to accommodate your molecule(s)?


From: phenixbb-bounces at phenix-online.org [mailto:phenixbb-bounces at phenix-online.org] On Behalf Of Ursula Schulze-Gahmen
Sent: Monday, June 06, 2016 4:47 PM
To: PHENIX user mailing list
Subject: [phenixbb] twinning detection

I have an extremely low resolution data set to 6.5 A.  The data were collected on a Pilatus detector, indexed and further processed in XDS, space group P321.  Pointless determines spacegroup to P3221 or P3121 and L-test shows no twinning. Phenix X-triage indicates twinning, but the twin fraction varies enormously depending on the method used: Britton analysis 0.337, H-test 0.260, ML 0.022. The UCLA twin server also thinks that data are twinned. How do I evaluate which information is right?
Also, I think I found a molecular replacement solution that is correct using these twinned data.

Ursula Schulze-Gahmen, Ph.D.
Project Scientist
UC Berkeley, QB3
360 Stanley Hall #3220
Berkeley, CA 94720-3220
(510) 643 9491
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