I forgot to acknowledge Pierre Legrand for the same suggestion. -Peer
Zbyszek Otwinowski and Fred Vellieux suggested to run the self-rotation on Fcalcs. This suggestion "solved" the problem, since there are similar peaks on the kappa=180° planes as well. However, I wasn't able to get rid of those peaks by playing around with resolution and integration radius. I must say that I am surprized, because - as Eleanor pointed out - I also expected to find peaks on the kappa=180° planes only in case of P6522 symmetry. Anyway, this experience reminds me to run some simple tests beforehand. -Peer
On 29.04.2015 15:31, Eleanor Dodson wrote:
Well - PG P6/mmm (possible SG P6522) will have peaks at kappa = 180 omega = 90 phi = 0 30 60 etc.. But if there is only one molecule / asymm unit there cant be an extra 2-fold. How big are the relative domains? Your interesting domain couldnt just be cleaved off could it? Eleanor On 29 April 2015 at 12:59, Peer Mittl <[email protected] <mailto:[email protected]>> wrote: 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.
