- phenixbb - phenix-online.org

Estimation of ligand binding affinity by occupancy refinement
by Zoran Stefanic 01 May '12

01 May '12

Dear all, I have a question about sensitivity of occupancy refinement in phenix. I have a series of datasets done at our home instrument of relatively modest resolutions from 2.8 to 3 A. These are performed on crystals soaked in progressively higher ligand concentrations. We are trying to see to which of the several active sites the ligand binds first so we went from low to high ligand concentrations. We wanted to estimate the amount of ligand bound by refining the occupancies of the ligand. We expect one active site to bind more strongly than the other two active sites. This was indeed what we observed but when we refine the occupancies of the ligands in weaker binding sites starting at 0.2 occupancies they rise to 0.5-0.6 although some atoms are totally out of density and some are in. B factors are reasonable, i.e. don't go wild. My question would be: how reliable is this estimation of ligand binding by occupancy refinement? Why doesn't the occupancy of ligands stay low if afterwards the density fit of the ligand looks rather unconvincing? Thank you in advance Zoran -- Dr. Zoran Stefanic Division of Physical Chemistry Rudjer Boskovic Institute Bijenicka 54 P.O. Box 180 Zagreb Croatia Phone: 00 385 1 457 1203 Fax: 00 385 1 468 0245

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metal coordination
by Panne Daniel 30 Apr '12

30 Apr '12

Hi all, I had a question concerning metal coordination (zinc in this case). I have used phenix.metal_coordination to generate geometry restraints for refinement. However phenix.refine does not write out the necessary LINK records into the PDB file. This seems to lead to problems later during validation, as the metal coordination is not properly recognized. What would be the best way to generate the LINK records in Phenix? Thanks, Daniel

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Error of Sculptor
by Zhang yu 26 Apr '12

26 Apr '12

Dear Phenixer, When I used Sculptor to generate a new model, there is a error which I can not figure out. I input a PDB file (*.pdb) and an alignment file (*.aln). The following is the log file (contents in ######). There seems something wrong with the *.aln file. ################# Reading PDB file ---------------- File name: **/**/******/******/**.pdb Separating solvent from macromolecules... Reading alignment files ----------------------- 1. **/**/**.aln ##################### The following is the content of the alignment file: **_** MVYSYTEKKRIRKDFGKRPQVLDVPYLLSIQLDSFQKFIEQDPEGQY----GLEAAFRSV **_** ---------MEIKRFGRIREVIPLPPLTEIQVESYRRALQADVPPEKRENVGIQAAFRET * **: :*: :* * .**::*::: :: * : *::****.. What is the problem with the alignment file? Thank you in advance! Fish

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cut-out mtz edition
by Dialing Pretty 26 Apr '12

26 Apr '12

Dear All, I just cut out a fragment of chain and the corresponding electron density from the whole molecule. Will you please give me some suggestion on how to edit the attached file so that those electron density not from the protein fragment can be erased? Or do you have other methods to produce high quality figure which just shows the fragment chain and the fragment eletron density? Cheers, Dialing

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Geometry Restraints - UPDATE
by Mario Sanches 25 Apr '12

25 Apr '12

Last week I asked a question about geometry restraints at low resolution. I would like to thank you all that took the time to answer, specially Pavel for looking at the data. First, here is the original question: __________________________________________ I am refining a low resolution structure (2.9A) using phenix.refine. As I continue the refinement Rwork/Rfree are dropping but my geometry statistics in general are very bad. My clashscore is getting worst and the RMS(angle) is really high. I have tried to play with the "wxc_scale" parameter and also ran phenix selecting the "Optimize X-ray/ADP weight" option. All attempts end with a RMS(angle) of ~3.8 and a Clashscore of ~190. Is there a known procedure to deal with this? I feel that my geometry weighing term is too loose but I don't know exactly how to tighten it other than decreasing the wxc_scale parameter. I have gone and manually corrected bad positions before but given the low resolution nature of the structure the clashes tend to be reestablished during refinement. Thank you in advance for your help, __________________________________________ It turns out that the reason to my nightmares was a highly anisotropic dataset. When I tried to fix geometry related problems in coot, phenix.refine was twisting the geometry back again, probably because it was trying to fit a lot of noise due to the anisotropy. Everything was getting worst, geometry, clashscore, and Ramachandran. Pavel finally corrected it by using this server: http://services.mbi.ucla.edu/anisoscale/ I should have been more diligent regarding that, since I could clearly see that my data was anisotropic from the diffraction images. I just didn't know how important this parameter could be. Anyways, phenix.xtriage will tell you if your data is anisotropic. The lesson is to pay attention to it. In my case, the quality of the electron density improved considerably, the geometry improved massively (manual intervention in coot was absolutely necessary, but now it stays correct after I manually fix the problems), clashscore lowered, etc. As a side note, it worked better without hydrogens in my case than with. It is certainly a parameter to try if you are having problems. Thank you all again for the tips. Mario Sanches -- Mario Sanches Postdoctoral Researcher Samuel Lunenfeld Research Institute Mount Sinai Hospital 600 University Ave Toronto - Ontario Canada M5G 1X5 http://ca.linkedin.com/in/mariosanches

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labelit.index with compatibility file
by "Weiergräber, Oliver H." 24 Apr '12

24 Apr '12

Hello, I have used labelit.check_pdb_symmetry to evaluate a P1 dataset and model for possible higher symmetry. C2 turned out to be a candidate solution. When I used the new asymmetric unit content file (xyz_coset0.pdb) to force indexing in the new SG: labelit.index /path/to/my/images/template_####.img 1 90 compatibility_file=xyz_coset0.pdb, the program crashes with AttributeError: 'NoneType' object has no attribute 'mosaicity_spot_coverage' This happens with the version included in phenix-1.7.3 as well as with the latest standalone labelit package. Any ideas what might be causing this? Maybe the new cell fails to refine? It is absolutely possible that forcing the higher symmetry SG leads to significant positional rmsd - I actually believe that P1 is correct, but it's definitly not far from C2. Best regards ================================================ PD Dr. Oliver H. Weiergräber Institute of Complex Systems ICS-6: Structural Biochemistry Tel.: +49 2461 61-2028 Fax: +49 2461 61-1448 ================================================ ------------------------------------------------------------------------------------------------ ------------------------------------------------------------------------------------------------ Forschungszentrum Juelich GmbH 52425 Juelich Sitz der Gesellschaft: Juelich Eingetragen im Handelsregister des Amtsgerichts Dueren Nr. HR B 3498 Vorsitzender des Aufsichtsrats: MinDir Dr. Karl Eugen Huthmacher Geschaeftsfuehrung: Prof. Dr. Achim Bachem (Vorsitzender), Karsten Beneke (stellv. Vorsitzender), Prof. Dr.-Ing. Harald Bolt, Prof. Dr. Sebastian M. Schmidt ------------------------------------------------------------------------------------------------ ------------------------------------------------------------------------------------------------ Kennen Sie schon unsere app? http://www.fz-juelich.de/app

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twinning question
by Patrick Loll 20 Apr '12

20 Apr '12

Dumb question here: When one runs the various twinning tests (e.g. phenix.xtriage), is one meant to use data processed in the higher symmetry SG, or the lower symmetry SG? A concrete example: I can process a data set in a 622 point group w/ reasonable merging statistics, but an abnormally low solvent content raises my suspicions. So do I process as P6, and submit these data to the twinning test? Or do I submit the data processed as P622? Pat --------------------------------------------------------------------------------------- Patrick J. Loll, Ph. D. Professor of Biochemistry & Molecular Biology Director, Biochemistry Graduate Program Drexel University College of Medicine Room 10-102 New College Building 245 N. 15th St., Mailstop 497 Philadelphia, PA 19102-1192 USA (215) 762-7706 pat.loll(a)drexelmed.edu

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Geometry Restraints
by Mario Sanches 20 Apr '12

20 Apr '12

I am refining a low resolution structure (2.9A) using phenix.refine. As I continue the refinement Rwork/Rfree are dropping but my geometry statistics in general are very bad. My clashscore is getting worst and the RMS(angle) is really high. I have tried to play with the "wxc_scale" parameter and also ran phenix selecting the "Optimize X-ray/ADP weight" option. All attempts end with a RMS(angle) of ~3.8 and a Clashscore of ~190. Is there a known procedure to deal with this? I feel that my geometry weighing term is too loose but I don't know exactly how to tighten it other than decreasing the wxc_scale parameter. I have gone and manually corrected bad positions before but given the low resolution nature of the structure the clashes tend to be reestablished during refinement. Thank you in advance for your help, -- Mario Sanches Postdoctoral Researcher Samuel Lunenfeld Research Institute Mount Sinai Hospital 600 University Ave Toronto - Ontario Canada M5G 1X5 http://ca.linkedin.com/in/mariosanches

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inverting a set of phase angles
by Mooers, Blaine H.M. (HSC) 19 Apr '12

19 Apr '12

Does phenix have a reflection file utility for correctly inverting a set of phase angles? Blaine Mooers Assistant Professor Department of Biochemistry and Molecular Biology University of Oklahoma Health Sciences Center S.L. Young Biomedical Research Center Rm. 466 Letter address: Shipping address: P.O. Box 26901, BRC 466 975 NE 10th Street, BRC 466 Oklahoma City, OK 73190 Oklahoma City, OK 73104-5419 office: (405) 271-8300 lab: (405) 271-8313 fax: (405) 271-3910 e-mail: blaine-mooers(a)ouhsc.edu<mailto:[email protected]> webpage: http://www.oumedicine.com/department-of-biochemistry-and-molecular-biology/…

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torsion NCS and SA
by dirk.reinert＠boehringer-ingelheim.com 19 Apr '12

19 Apr '12

Dear all, Is it safe to use torsion NCS (refinement.ncs.type="torsion") and torsion SA (refinement.main.simulated_annealing_torsion= "true") as a default? Thanks for advice, Dirk --- Dr. Dirk Reinert Boehringer Ingelheim Pharma GmbH & Co. KG Dept. Lead Identific. and Optim. Sup. Ge Tel.: +49 (7351) 54-97892 Fax: +49 (7351) 83-97892 mailto:[email protected] Boehringer Ingelheim Pharma GmbH & Co. KG, Sitz: Ingelheim am Rhein; Registergericht Mainz: HR A 22206; Komplementär Boehringer Ingelheim Deutschland GmbH; Geschäftsführung: Dr. Engelbert Günster (Vorsitzender), Ursula Fuggis-Hahn, Ralf Gorniak, Michael Klein, Dr. Martin Wanning; Vorsitzender des Aufsichtsrates: Prof. Dr. Dr. Andreas Barner; Sitz: Ingelheim am Rhein; Registergericht Mainz: HR B 23260 Diese E-Mail ist vertraulich zu behandeln. Sie kann besonderem rechtlichen Schutz unterliegen. Wenn Sie nicht der richtige Adressat sind, senden Sie bitte diese E-Mail an den Absender zurück, löschen die eingegangene E-Mail und geben den Inhalt der E-Mail nicht weiter. Jegliche unbefugte Bearbeitung, Nutzung, Vervielfältigung oder Verbreitung ist verboten. / This e-mail is confidential and may also be legally privileged. If you are not the intended recipient please reply to sender, delete the e-mail and do not disclose its contents to any person. Any unauthorized review, use, disclosure, copying or distribution is strictly prohibited.

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