Two questions
(1) What is the rotation+translation operation that relates
solution #1 an solution #2?
(2) Have you double-checked and then checked yet again that both
solutions are in P43212? Could it be that one of them ended
up in, say, P414241?
it's happened to me :-(
Ethan
On Sunday, 5 September 2021 21:45:39 PDT Lande Fu wrote:
> Dear all,
>
>
> Recently I had a strange problem related to MR and it confused me and my
> colleagues a lot.
>
> My protein crystal was diffracted at 2.63A and I processed it normally then
> did MR with Phaser (in P432(1)2). The result itself looked okay and well fit
> the map. However, the R-work/ R-free value was stuck at 0.3012/0.2434 after
> cycles of manual refinement. Then I redid MR with another model from PDB
> website and got another solution which looked similar to previous one and the
> R-work/ R-free value can be lowered to 0.2496/0.1967 after refinement.
>
> Strange things appeared when I opened the two MR solutions in single coot
> window (Fig 1). The two models were neither overlaying each other nor on the
> symmetry of the other. The two models are nearly identical (actually the
> first model was a previous structure built from PDB model) and have same
> construct with my protein. There is no TNCS, twinning or other noticeable
> problems detected according to aimless log.
>
> My question is: why phaser gives two different solutions from same map and
> similar model and result in different R-work/ R-free value? Does that mean
> there are two phases in the map? Does that imply multiple lattices in my
> crystal?
>
> I tried to research myself but did not find any related explanation for it.
> Please let me know if you need more information. Thank you in ahead.
>
>
> Regards,
>
> Lande Fu
--
Ethan A Merritt
Biomolecular Structure Center, K-428 Health Sciences Bldg
MS 357742, University of Washington, Seattle 98195-7742
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