Hi Peer,
I would definitively second Pierre's suggestion to use calculated data to simulate the self-rotation results.
Do you see any density for the "lost" domain, or nothing at all?
Could it be that this domain is flipped by 180° in part of the molecules, maybe due to a proteolytic cleavage?
Best,
Heman
-----Ursprüngliche Nachricht-----
Von: CCP4 bulletin board [mailto:[log in to unmask]] Im Auftrag von Peer Mittl
Gesendet: Mittwoch, 29. April 2015 14:00
An: [log in to unmask]
Betreff: [ccp4bb] self-rotation in the absence of NCS
We are working with a multi-domain protein crystallized in SG P6_5 with one molecule per asymmetric unit. The structure was refined at 2.00 A resolution with reasonable R-factors but unfortunately the domain we are most interested in seems to be disordered. Interestingly, the self-rotation function shows peaks on the kappa=180° plane (omega=90°, phi=19° (and every 30°)), with more than 50% origin peak height.
Therefore, we are wondering if perhaps the space group assignment might be sub-optimal. Any explanations how these self-rotation peaks could occur and how we could extract meaningful information to resolve the disordered domain are welcome.
Best regards,
Peer
P.S. Some additional information: pointless suggests SG P6_5, the data doesn't seem to be twinned (L-test), the refined part of the structure has no "internal symmetry" and refinement in P1 doesn't reveal the "lost" domain.
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Peer Mittl, PD Dr.
Biochemisches Institut
Universität Zürich
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