Dear Jacob,
The most important thing to note is the final LLG values of the two solutions, which differ by the enormous number of more than 21000 units. The first solution is in far better agreement with the data. I think it's an artefact of Phaser being a bit too optimistic about how little data can be used in the step of finding the sixth tetramer, which has reduced the signal too much to tell the right answer from wrong ones at that resolution. I don't know why an incorrect solution got a TFZ score of 16.2, which implies that it's not completely random (is there some approximate internal symmetry?), but if that TFZ had not been greater than 8, Phaser would not have reported the second solution at the end, after the full resolution refinement that makes the correct solution very clear.
Best wishes,
Randy Read
> On 10 Sep 2015, at 01:54, Keller, Jacob <[log in to unmask]> wrote:
>
> Dear Crystallographers,
>
> In an effort to cover my bases in a structure of spacegroup P3212 with hemihedral twinning, I re-solved the structure in P1, expecting if all went well to see the tetrameric search model appear by appropriate crystallographic operators in the P1 cell. The first complete MR solution indeed conformed to this, but the second solution was interesting: the last placed tetramer had unexpectedly-strange Euler angles (see below at "###"). Is there something to this, or is it something I don't yet understand about Euler angles? Or could this be related somehow to the twinning?
>
> All the best,
>
> Jacob Keller
>
>
>
> Solution #1 annotation (history):
> SOLU SET RFZ=8.7 TFZ=* PAK=0 LLG=74 RF++ TFZ=18.8 PAK=0 LLG=327 (& TFZ=17.8
> PAK=0 LLG=312 & TFZ=16.7 PAK=0 LLG=295 & TFZ=16.6 PAK=0 LLG=290) LLG+=(327 & 700
> & 1254 & 1900) LLG=50887 PAK=0 RFZ=8.2 TFZ=19.7 PAK=0 LLG=896 LLG=70879
> SOLU SPAC P 1
> SOLU 6DIM ENSE ensemble1 EULER 240.0 0.0 0.0 FRAC -0.06 0.06 0.01 BFAC -0.14
> SOLU 6DIM ENSE ensemble1 EULER 120.0 180.0 0.0 FRAC -0.06 0.06 3.01 BFAC 0.19
> SOLU 6DIM ENSE ensemble1 EULER 120.0 0.0 0.0 FRAC 0.94 -0.94 0.34 BFAC 0.19
> SOLU 6DIM ENSE ensemble1 EULER 0.0 180.0 0.0 FRAC 0.94 -0.94 2.34 BFAC 0.20
> SOLU 6DIM ENSE ensemble1 EULER 240.0 180.0 0.0 FRAC -0.06 -0.94 2.67 BFAC 0.02
> SOLU 6DIM ENSE ensemble1 EULER 0.0 0.0 0.0 FRAC -0.06 -0.94 -0.33 BFAC -0.00
> SOLU ENSEMBLE ensemble1 VRMS DELTA -0.1302 RMSD 0.56 #VRMS 0.43
>
> Solution #2 annotation (history):
> SOLU SET RFZ=8.7 TFZ=* PAK=0 LLG=74 RF++ TFZ=18.8 PAK=0 LLG=327 (& TFZ=17.8
> PAK=0 LLG=312 & TFZ=16.7 PAK=0 LLG=295 & TFZ=16.6 PAK=0 LLG=290) LLG+=(327 & 700
> & 1254 & 1900) LLG=50887 PAK=0 RFZ=7.1 TFZ=16.2 PAK=2 LLG=833 LLG=49532
> SOLU SPAC P 1
> SOLU 6DIM ENSE ensemble1 EULER 240.0 0.0 0.0 FRAC -0.08 0.06 0.01 BFAC -1.73
> SOLU 6DIM ENSE ensemble1 EULER 120.0 180.0 0.0 FRAC -0.08 0.06 3.01 BFAC -1.69
> SOLU 6DIM ENSE ensemble1 EULER 120.0 0.0 0.0 FRAC 0.92 -0.94 0.35 BFAC -1.40
> SOLU 6DIM ENSE ensemble1 EULER 0.0 180.0 0.0 FRAC 0.92 -0.94 2.35 BFAC -1.32
> SOLU 6DIM ENSE ensemble1 EULER 240.0 180.0 0.0 FRAC -0.08 -0.94 2.68 BFAC -1.81
> ### SOLU 6DIM ENSE ensemble1 EULER 138.2 179.6 70.7 FRAC 0.25 -0.56 3.17 BFAC 50.00
> SOLU ENSEMBLE ensemble1 VRMS DELTA -0.1166 RMSD 0.56 #VRMS 0.44
>
>
>
>
> *******************************************
> Jacob Pearson Keller, PhD
> Looger Lab/HHMI Janelia Research Campus
> 19700 Helix Dr, Ashburn, VA 20147
> email: [log in to unmask]
> *******************************************
------
Randy J. Read
Department of Haematology, University of Cambridge
Cambridge Institute for Medical Research Tel: + 44 1223 336500
Wellcome Trust/MRC Building Fax: + 44 1223 336827
Hills Road E-mail: [log in to unmask]
Cambridge CB2 0XY, U.K. www-structmed.cimr.cam.ac.uk
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