Hi, The dimensions for a native are 58 103 220, with small differences for the derivatives.
Best, Carmela. > On 3 Dec 2017, at 18:18, Sridhar Prasad <[email protected]> wrote: > > Hello, > Can you please share the unit cell dimensions. > > Cheers, > Sridhar > > On Dec 3, 2017 9:13 AM, "Carmela Garcia" <[email protected] > <mailto:[email protected]>> wrote: > Dear all, > > I know that some years ago a similar situation was discussed here, and I > wonder if someone has new insights about these problems. > > My protein is a dimer in solution. I tried several derivatives for SAD, and > all my datasets seem to have the same problem, including the native crystals. > I processed the data with XDS and the space group determination was done with > Pointless, being a P212121. > > Checking the quality of the data, I found several problematic results: > > - Translational NCS is detected. There is a peak at (0.50, 0.40, 0.50) > - The L test suggests twinning (L statistic = 0.41) > - The mean acentric moments I from input data have the following values: > <I^2>/<I>^2 : 4.396 > <I^3>/<I>^3: 34.478 > <I^4>/<I>^4: 361.084 > All these values are way higher than the expected ones for non-twinned > data. > - The twinning fraction from L-test is 0.22 > > This would all suggest that my space group is wrong, and that I should > proceed in a lower symmetry group, but I don’t know how should I continue. I > know about cases where a P43212 or a P41212 were suggested but in fact the > correct space group was P212121, but I would not know how to continue going > down. Checking my images, I can see some streaky spots, and the crystals grow > first as needles that eventually become plates and rarely crystals. All these > would be a clear indicative of twinning, but I would not expect to have the > same results with different derivatives. We thought about some kind of > reticular twinning, and I wonder if there is a way to solve it. > > Any idea about how to proceed or to identify the problem would be welcome. > > Thanks, > > Carmela. > > > > Carmela Garcia-Doval > University of Zurich > Department of Biochemistry > Winterthurerstrasse 190 > <https://maps.google.com/?q=Winterthurerstrasse+190&entry=gmail&source=g> > CH-8057 Zurich > Switzerland > E-mail: [email protected] <mailto:[email protected]>
