Hi

Kay means, of course, the ACA meeting in Albuquerque, not the IUCr in Montreal!

Authors of the major processing packages will be competing for your attention...

Harry
--
** note change of address **
Dr Harry Powell, MRC Laboratory of Molecular Biology, Francis Crick Avenue, 
Cambridge Biomedical Campus, Cambridge, CB2 0QH
Chairman of European Crystallographic Association SIG9 (Crystallographic 
Computing)

> On 23 Feb 2014, at 07:55, Kay Diederichs <[email protected]> 
> wrote:
> 
> Projects and problems like this are clearly a justification for asking to 
> deposit not only the results from data processing, but also the raw data 
> frames. These would allow developers to improve the models underlying their 
> algorithms, and to find those corner cases where the algorithms break. That 
> would help everyone.
> 
> Maybe you could make this dataset (and sequence) available for the 
> forthcoming IUCr conference, as an example for a difficult dataset? (send 
> email to Ed Collins or me) You would profit from the fact that experienced 
> crystallographers do their best to make the most of your data.
> 
> best,
> 
> Kay
> 
>> On Fri, 21 Feb 2014 20:13:33 -0600, Chris Fage <[email protected]> wrote:
>> 
>> Thanks for the assistance, everyone.
>> 
>> For those who suggested XDS: I forgot to mention that I have tried Mosfim,
>> which is also better than spot fitting than HKL2000. How does XDS compare
>> to Mosflm in this regard?
>> 
>> I am not refining the high R-factor structure with NCS options. Also, my
>> unit cell dimensions are 41.74 A, 69.27 A, and 83.56 A, so there isn't one
>> particularly long axis.
>> 
>> I'm guessing the low completeness of the 1.65 angstrom dataset has to do
>> with obstacles the processing software encountered on a sizable wedge of
>> frames (there were swaths of in red in HKL2000). I'm not sure why this
>> dataset in particular was less complete than the others.
>> 
>> Thanks,
>> Chris
>> 
>> 
>>> On Fri, Feb 21, 2014 at 6:41 PM, Chris Fage <[email protected]> wrote:
>>> 
>>> Dear CCP4BB Users,
>>> 
>>> I recently collected a number of datasets from plate-shaped crystals
>>> that diffracted to 1.9-2.0 angstroms and yielded very nice electron
>>> density maps. There is no major density unaccounted for by the model;
>>> however, I am unable to decrease Rwork and Rfree beyond ~0.25 and
>>> ~0.30, respectively. Probably due to the more 2-dimensional nature of
>>> my crystals, there is a range of phi angles in which the reflections
>>> are smeared, and I am wondering if the problem lies therein.
>>> 
>>> I would be grateful if anyone could provide advice for improving my
>>> refinement statistics, as I was under the impression that the
>>> R-factors should be ~5% lower for the given resolution.
>>> 
>>> A few more pieces of information:
>>> -Space group = P21, with 2 monomers per asymmetric unit;
>>> -Chi square = 1.0-1.5;
>>> -Rmerge = 0.10-0.15;
>>> -Data were processed in HKL2000 and refined in Refmac5 and/or
>>> phenix.refine;
>>> -PHENIX Xtriage does not detect twinning, but hints at possible weak
>>> translational pseudosymmetry;
>>> -I was previously able to grow one atypically thick crystal which
>>> diffracted to 1.65 angstroms with Rwork/Rfree at 0.18/0.22.
>>> Unfortunately, the completeness of the dataset was only ~90%.
>>> 
>>> Regards,
>>> Chris
>> 

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