[phenixbb] P43212 spacegroup change to C2221?

Frank von Delft frank.vondelft at sgc.ox.ac.uk
Wed Aug 26 14:26:04 PDT 2009


Hi Peter, how did you generate that plot?  Is it a general app, or by 
hand?  Because it's a cool way for getting your head around the twinning 
problems...
Cheers
phx


Peter Zwart wrote:
> Can you send the exact unit cell parameters? The number you give now
> are to rough to make a fair comparison.
>
> In any case, C2221 does lie directly below P43212 (see attached
> figure), so you have a good chance that is a possibility.
> On the other hand, so are P43 and P212121.
> It is fairly straightforwadr to try all, just cumbersome.
> I suggest however you get your data in P1, and solve it in that spacegroup.
> Subsequently, run
>
> phenix.xtriage p1data.mtz reference.structure.file=MR.1.pdb
>
> and start interpreting the RvsR tables.
> Contact me directly if you have difficulties with this, or share with
> the bb as this is a very instructive exercise.
>
> Cheers
>
> Peter
>
>
>
>
>
>
>
>
>
>
>
>
>
>
> 2009/8/25 Leigh Allen <c.leigh.allen at gmail.com>:
>   
>> Hello Phenix users.
>>
>> I recently solved the structure of my enzyme using SAD to a resolution of
>> 1.9A.  The R values were 0.19/0.25 and the space group was P43212 with a
>> unit cell ~80, 80, 220.
>>
>> I then starting collecting datasets cocrystallized with ATP analogs and
>> noticed that a lot of my datasets have a different unit cell when scaled in
>> P43212.  It comes out to be ~60, 60, 220 and I can NOT get a solution in
>> Phaser with this data.  If I scale it in C2221, then the unit cell is the
>> same (80, 80, 220), but upon refinement, the R factors don't go much below
>> 0.26/0.32.  Has anyone ever seen something like this happen?  I'm unsure if
>> I should feel like the solution is C2221 since there are space groups of
>> higher symmetry with similar residuals that seem plausible in indexing just
>> the smaller unit cell. Should I keep trying to get a solution out of the
>> data that leads to different unit cell parameters, but has higher symmetry?
>>
>> Xtriage seems to find twinning, but I think it's from NCS since my ASU
>> contains a homodimer.  I could also be wrong about this...
>>
>> Thanks in advance for any advice!
>>
>> *******
>> Leigh Allen
>> Ph.D Candidate
>> McCafferty Lab
>> Duke University
>> Department of Chemistry
>>
>> _______________________________________________
>> phenixbb mailing list
>> phenixbb at phenix-online.org
>> http://www.phenix-online.org/mailman/listinfo/phenixbb
>>
>>
>>     
>
>
>
>   
>
> ------------------------------------------------------------------------
>
> ------------------------------------------------------------------------
>
> _______________________________________________
> phenixbb mailing list
> phenixbb at phenix-online.org
> http://www.phenix-online.org/mailman/listinfo/phenixbb
>   



More information about the phenixbb mailing list