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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CH-8057 Zürich

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