Hi Yuri, you did not mention the resolution... From your email I guess it is 1.9A, is it correct? Anyway, to bypass the uncertainties of the space group choice (and artifacts due to constraints it applies) you can always process your data in P1, solve and refine you model (applying NCS if necessary; and yes, you are not solving completely new structure - you solved it many times before, so you know the answer pretty much!) and see how the solution obtained this way compares with whatever else you get from more wise strategy. Pavel. On 4/16/11 7:50 PM, Yuri wrote:
I am solving a structure of an enzyme that I have solved many times before, the only difference is a single mutation in the active site. The crystal grew in basically exact conditions (macroscopically speaking they look different) as the other mutants I had. I scaled the data P 43 21 2 Rsym 0.068. Like all the other data sets I had before. This time however, the initial model has Rfree of about 0.27 and the maps look more like those of a 2.5 - 2.8 structure. My experinence with this enzyme is that I should be looking at around 0.22 or lower Rfree, and pretty clear maps as I saw for my 1.9 structure. Xtriage does not detect any pathologies. I rececked my scaling log file, and it lists the systematic absences for the data. I see some that are not that "weak" for instance : h k l I/sigma 0 0 1 6.0 0 0 2 5.8 0 0 13 7.8
So I am inclined to reprocess my data in P 4 2 2. Are these "symptoms" of a possible wrong space group assignment? Is there something else obvious I am overlooking? Thank you
-- Yuri Pompeu
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