Re: [phenixbb] regarding ncs distance

Hi Pavel, Whenever I run ncs using the default parameters I get the following: The current limit is: refinement.ncs.excessive_distance_limit=1.5 The number of distances exceeding this limit is: 364 Please correct your model or redefine the limit, e.g. with: refinement.ncs.excessive_distance_limit=3 To disable this message completely define: refinement.ncs.excessive_distance_limit=None It runs fine when you put refinement.ncs.excessive_distance_limit=None in the command line. My question is what would be the best distance for the program to run without this message. thanks, Shya

Hi Raja,

here are a few comments:

- if you used TLS previously and then run a refinement without TLS (that is "strategy=..." does not include "tls"), the previous TLS refinement gets invalidated, because phenix.refine will automatically convert ANISOU into isotropic equivalent. It says it somewhere in .log file.

- the "run 1" looks better than the others indeed (judging by the R-factors and bond/angles RMSDs at this resolution).

- your original concern was the geometry problems, so using H in refinement, as well as optimizing weights, may help fixing them. So I would check the geometry too for all the runs below, and not only R-factors.

- yesterday Kendall suggested a set of good ideas to try out regarding NCS.

- I did not understand what you mean by "default extension of high resolution range in PHENIX". phenix.refine uses all reflections that it finds in your input data files, unless specified otherwise using high/low resolution cutoffs and sigma cutoffs. phenix.refine does not collect any additional data for you -:)

- at 2.9A it is very likely that you still ok to refine individual ADPs and switching to group ADP can increase R-factors. So no surprises here. I doubt that using bulk-solvent correction and anisotropic scaling increases the R-factors; probably you tried it in combination with something else, and that "something else" was the cause of increased R-values.

- are you using the latest version of PHENIX ?

Pavel.

On 11/18/09 8:47 AM, Raja Dey wrote:

...

Hi Pavel, I finished 4 runs as you suggested. See below: run1. phenix.refine 1205A-p21212.mtz nov138_001.pdb ncs_groups.params main.ncs=true ncs.find_automatically=false refinement.ncs.excessive_distance_limit=None xray_data.high_resolution=2.9 refinement.main.number_of_macro_cycles=5 output.write_maps=true output.prefix=nov17 REMARK Start: r_work = 0.2803 r_free = 0.3036 bonds = 0.012 angles = 1.488 REMARK Final: r_work = 0.2438 r_free = 0.2994 bonds = 0.009 angles = 1.309 b_ave=70.09

run2. with wxc and wxu optimization phenix.refine 1205A-p21212.mtz nov138_001.pdb ncs_groups.params main.ncs=true ncs.find_automatically=false refinement.ncs.excessive_distance_limit=None xray_data.high_resolution=2.9 refinement.main.number_of_macro_cycles=5 optimize_wxc=true optimize_wxu=true output.write_maps=true output.prefix=nov17-opt REMARK Start: r_work = 0.2803 r_free = 0.3036 bonds = 0.012 angles = 1.488 REMARK Final: r_work = 0.2143 r_free = 0.2961 bonds = 0.032 angles = 3.281 b_ave=64.71

phenix.reduce may21_pdbset.pdb > may21_pdbset_h_added.pdb

run3. with hydrogen phenix.refine 1205A-p21212.mtz nov138_001_h_added.pdb ncs_groups.params main.ncs=true ncs.find_automatically=false refinement.ncs.excessive_distance_limit=None xray_data.high_resolution=2.9 refinement.main.number_of_macro_cycles=5 output.write_maps=true output.prefix=nov17-wh REMARK Start: r_work = 0.2860 r_free = 0.3123 bonds = 0.085 angles = 1.672 REMARK Final: r_work = 0.2381 r_free = 0.3029 bonds = 0.017 angles = 1.685 b_ave=77.7

run4. with both hydrogen and optimization phenix.refine 1205A-p21212.mtz nov138_001_h_added.pdb ncs_groups.params main.ncs=true ncs.find_automatically=false refinement.ncs.excessive_distance_limit=None xray_data.high_resolution=2.9 refinement.main.number_of_macro_cycles=5 optimize_wxc=true optimize_wxu=true output.write_maps=true output.prefix=nov17-wh-opt REMARK Start: r_work = 0.2860 r_free = 0.3123 bonds = 0.085 angles = 1.672 REMARK Final: r_work = 0.2447 r_free = 0.3032 bonds = 0.020 angles = 1.922 b_ave=80.75

It looks output from run1 is the best, adding hydrogen and optimizing wxc and wxu did not help much. I have had little better Rfree and rmsd at the end of my last run.

You are right. the commands I used at the last stage looks weird. Before that run I have used "strategy=rigid_body+individual_sites+group_adp+tls" and also included bulk_solvent and scaling. The map is pretty good. But, the number of reflections used in the refinement was more than that in mtz file and that was the warning in the pdb validation summary letter. I think that's because default extension of high resolution range in PHENIX. So, I needed to run 1 macro cycle with a little lower high resolution 2.9A with the last refined pdb. I found those are the combination of commands gives the best R, Rfree and rmsd for bonds and angles. As soon as I was including bulk solven and scaling correction and/or b_group the values were increasing. Although I don't have clear explanation, but that is what I found. Any way these are very little differences and might not be so important.

I fixed the problem in dna. The problem was related with the occupancy of the 2 alternate conformations of dna. But, I still have 8 amino acids' (out of 400) phy, psy out side Ramachandran plot. Probably this does not mater much if I I deposite this co-ordinate in PDB. Thanks for all your suggestions though.

Regards... Raja

----- Original Message ----- From: Pavel Afonine Date: Tuesday, November 17, 2009 12:20 pm Subject: Re: [phenixbb] fixing geometry for deposition To: PHENIX user mailing list

...

Hi Raja,

...

I used the following commands at the last stage of

refinement:>

...

phenix.refine 1205A-p21212.mtz nov138_001.pdb

simulated_annealing=false ncs_groups.params main.ncs=true ncs.find_automatically=false refinement.ncs.excessive_distance_limit=None main.bulk_solvent_and_scale=false strategy=rigid_body+individual_sites xray_data.high_resolution=2.9 refinement.main.number_of_macro_cycles=1 output.write_maps=true output.prefix=nov139 --overwrite

...

The above command seems extremely weird to me for the following reasons: 1) Bulk-solvent correction and anisotropic scaling always has to be done (unless you are experimenting with fake data or these corrections have been already applied to Fobs, which is bad ideas anyway). By using "main.bulk_solvent_and_scale=false" you turn bulk-solvent correction and anisotropic scaling off.

2) By default, phenix.refine does 3 refinement macro-cycles, but often (depending how far you are from the final model) this is not enough for refinement to converge, so increasing it to 5 or so is a good idea. Doing just one macro-cycle (refinement.main.number_of_macro_cycles=1) does not make much sense to me. By the way, you can use shortcuts like "main.number_of_m=5".

3) You can drop this off the list since it is the default setting anyway: "simulated_annealing=false".

4) The refinement strategy: "strategy=rigid_body+individual_sites". Normally, you do the rigid body refinement at initial stages of refinement when your model is poor, and not at the final run. This is because the rigid-body refinement can be very rude on your model: bonds can be broken between rigid groups since no restraints is used, for example. Also, it's strange that the ADP refinement is turned off - it's always good to do, and at 2.8A you can still refined individual ADPs. Well, I'm not mention using TLS...

So, I would modify the above command as following:

phenix.refine 1205A-p21212.mtz nov138_001.pdb ncs_groups.params main.ncs=true ncs.find_automatically=false refinement.ncs.excessive_distance_limit=None xray_data.high_resolution=2.9 output.write_maps=true output.prefix=test --overwrite

and try running it as is, and with adding keywords "optimize_wxc=true optimize_wxu=true", using a model with or w/o H riding H atoms, etc... what I wrote in my previous email.

...

Regarding amino acids phy, psy..... I tried real space

refinement/regularization in coot,

This is not the same as what I suggested to try in my previous email. Anyway, I would first try the modified command above and only then try other suggested things.

Good luck, Pavel.

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