[phenixbb] bad geometry problem
pafonine at lbl.gov
Wed Jun 20 13:22:44 PDT 2012
thanks for sending me the data. I spent 15 minutes trying a few things
and here is the statistics I get:
r_work = 0.2454 r_free = 0.2700
ALL-ATOM CLASHSCORE : 13.60
OUTLIERS : 0.89 %
ALLOWED : 5.33 %
FAVORED : 93.78 %
ROTAMER OUTLIERS : 8.64 %
CBETA DEVIATIONS : 0
which isn't that bad compared to the starting point:
r_work = 0.2469 r_free = 0.2613
ALL-ATOM CLASHSCORE : 48.87
OUTLIERS : 2.49 %
ALLOWED : 5.33 %
FAVORED : 92.18 %
ROTAMER OUTLIERS : 29.47 %
CBETA DEVIATIONS : 10
Here is what I did (it's just one of possible ways of doing this; other
scenarios may works as good as this one or better!):
- add H atoms:
phenix.reduce model.pdb > model_H.pdb
- then run a quick geometry regularization:
phenix.pdbtools model_H.pdb --geom
- then strip off H:
phenix.reduce -trim model_H_regularized.pdb > start.pdb
- then run refinement using NCS and Ramachandran plot restraints:
phenix.refine start.pdb def_data.mtz main.ncs=true --overwrite
output.prefix=def2 main.number_of_mac=5 ramachandran_restraints=true
- then take outcome of previous refinement and run the same refinement
plus weights optimization:
phenix.refine def2_001.pdb def_data.mtz main.ncs=true --overwrite
output.prefix=def3 main.number_of_mac=5 ramachandran_restraints=true
Also, looking at the original maps I see a lot of places where simple
fixing in Coot is just obvious, for both - rotamers and Ramachandran
outliers. So you should do it first of all.
Also, use Ramachandran restraints ONLY to preserve good starting model
and NOT to fix problems.
All in all, geometry problems you were concerned about are all easily
fixable. One of the reason why these problems arise is that the map is
really looking like 3A resolution map, may be even worse; plus there are
places in the model that you need to fix manually (refinement would not
be able to fix them).
I will send you the files off-list.
On 6/19/12 1:17 AM, Qian Sarah wrote:
> Hi, this may not be a new problem, but I tried every stretagy that I
> know from bb, but the geometry is still very bad. So I wish I can get
> some help from here.
> Crystal information:
> SAD data. Resolution 3.0. There is no anisotropy in the data.
> R/Rfree : 22.7/26.8 (Rfree-flag is always from the Refine_data.mtz
> file generated after the first refinement.)
> RMS(angles): 1.453
> Ramachandran outliers: 3.0%
> Ramachandran favored: 91.2%
> Rotamer outliers: 18.7% !!
> Clashscore: 31.84
> overall score: 3.47
> I tried different strategies, like autobuild and then refine; set
> wxu/wxc=0.3/0.3; turn on "Ramachandran restrains", "fix bad sidechain
> romaters"etc, however the paramters are still very bad, especially the
> rotamer outliers. Then I rebuild them manually in coot,after
> refinement the parameters are even worse.
> p.s. phenix version: phenix-1.7.3-dev-1046.
> Thank you very much!
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