January 2012 - phenixbb - phenix-online.org

Twin_law in GUI Phenix Refinement
by Tri Ngo 26 Jan '12

26 Jan '12

Hi phenix users, I have two questions when using Phenix Refinement. 1. I'd like to run phenix refinement with twin data but I don't know how to define twin_law using GUI Phenix refinement module in Linux. 2. I used phenix refinement in Windows to refine a 2.3A structure. My problem is the Rfree is quite high. - I applied twin refinement + TLS + NCS and SA refinement (wxu_scale = 1) Start: r_work = 0.2149 r_free = 0.2833 bonds = 0.016 angles = 1.988 Final: r_work = 0.2029 r_free = 0.2735 bonds = 0.008 angles = 1.448 - Then I use auto-weight to optimize the Rfree. optimize_xyz_weight = True optimize_adp_weight = True wxc_scale = 0.5 wxu_scale = 1 Start: r_work = 0.2152 r_free = 0.2735 bonds = 0.008 angles = 1.322 Final: r_work = 0.2309 r_free = 0.2781 bonds = 0.003 angles = 0.848 I think the bond rmsd and angle rmsd were too small in this final refinement. Do you think it's normal or I need to try more? Thank you very much for your helpful input. Best wishes, -- * TriNgo * Structural Biology Lab School of Medicine - Sungkyunkwan University Phone: 031-299-6150 Cell: 010-7774-8210

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model_vs_data
by Karolina Michalska 26 Jan '12

26 Jan '12

Hi everybody, I 've run model_vs_data for one of my structures and here is what I got: Information extracted from PDB file header: program_name : REFMAC year : None r_work : 0.15793 r_free : 0.19845 high_resolution : 1.45 low_resolution : 36.92 sigma_cutoff : None matthews_coeff : None solvent_cont : None TLS : False (number of groups: 0) After applying resolution and sigma cutoffs: n_refl_cutoff : 26357 r_work_cutoff : 0.1450 r_free_cutoff : 0.1687 Can someone, please, explain why there is such a big difference in R values? When I do refinement in phenix I get practically the same results that Refmac produces. Thanks, Karolina

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links in phenix
by Christian Roth 26 Jan '12

26 Jan '12

Hi, I have a pdb with a sugar chain as ligand. I used phenix ready set to get the links according to the link remarks in the pdb. However when I look into the edits file. All links are defined as geometry restraints and despite it is alpha 1-4 all bond restraints differ slightly in their length. Within the pdb file the definitions for the links were set to alpha1-4. A Similar thing happend with a peptide link between 2 Aminoacids which have not a continously numbering because of a deletion, but it is a simple peptide bond. I modified the .link.edits file accordingly for the sugars like this ---------- refinement.geometry_restraints.edits { apply_cif_link { data_link = ALPHA1-4 atom_selection_1 = name O4 and chain B and resname GLC and resseq 1 atom_selection_2 = name C1 and chain B and resname GLC and resseq 2 } } ------------ And applied a trans link for the peptide bond I added the modified file as additional parameter file in the gui. However in the final .eff file I found just the old restraints from the previous run. In the final .eff file it is stated that the file with my updated links is loaded ------ gui { base_output_dir = "/homes/roth/structure/250/082_c2_5/refinement/phenix" tmp_dir = "/homes/roth/structure/250/082_c2_5/refinement/phenix/phenix/tmp" send_notification = False notify_email = "christian.roth(a)bbz.uni-leipzig.de" add_hydrogens = True skip_rsr = False phil_file = "/homes/roth/structure/250/082_c2_5/refinement/phenix/refmac20link.link.edits" ----- Somehow the old restraits are already in the .eff file and the new ones are ignored how I could I avoid this. Simply closing the GUI an reopening? A second question is a very non standard peptide link due to a SNN residue in the chain. Based on the link a geometry restrain is created througn phenix.link_edits There is a slight difference in the length between the N- terminal and the C-terminal peptide bond. Which is probably fine and the resoution is good enough (roughly 2 Ang.) that is looks fine, but no angle definitions for phi psi and so on are stated. What is the best way to define this two bonds correctly for the subsequent refinement? A third question is a alpha1-4 link which extend to a symmetry related sugar. How I incorporate the symmetry information into the link? A last question regarding the hydrogens in refinement. For rebuilding it is nice to remove the hydrogens. Normally I use the commandline for this purpose. But It would be nice to do it automatically after refinement as a third pdb output in addition to the two standard outputs phenix_output.pdb and the phenix_output_reduce.pdb. Is there an option in the GUI to do this automatically. I thought I have seen this previously but cannot find it anymore I am sorry for this long Mail and so many question. I hope you could help me to clarify some the things. Best Regards Christian

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DEN Refinement in phenix 1.7.3
by Eike Schulz 25 Jan '12

25 Jan '12

Dear phenixbb, I have noticed that in (since?) the latest release it is possible to activate DEN refinement in phenix.refine. I assume this refers to deformable elastic networks right? What is your experience with DEN refinements ? As I could not find any reference to it in the documentation I would be happy to have feedback on when to use and when to avoid it e.g. resolution limits etc. and what to watch out for. Many thanks in advance Eike

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cif files
by Shya Biswas 24 Jan '12

24 Jan '12

Hi all, It appears that the cif file generated from prodrg (REFMAC format) is not recognised by phenix during refinement. Did anyone have similar issues or i am doing something wrong? somehow the geometries obtained from elbow are not right for my ligand so had to use prodrg to generate cif files. thanks, Shya

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Refinement of two co-factors/ligands at the same position
by Kornelius Zeth 23 Jan '12

23 Jan '12

Dear all, how can I refine two different co-factors/ligands ('XXX and YYY', with differing occupancy and cif-Files) located at the same position within an enzyme? What about the chain IDs, segment IDs etc? Thanks and best wishes Kornelius -- Kornelius Zeth ZMBP, Uni-Tuebingen Auf der Morgenstelle 1 72076 Tübingen Germany

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There's BARELY A WEEK left to apply for RapiData 2012, a course on Data Collection and Structure Solving at the NSLS.
by Robert Sweet 21 Jan '12

21 Jan '12

Half of the seats are still available for RapiData 2012, the fourteenth offering of our popular course: Rapid Data Collection and Structure Solving at the NSLS: A Practical Course in Macromolecular X-Ray Diffraction Measurement The course will be held 22-27 April 2012: http://www.bnl.gov/rapidata/. Students could be at any level from advanced undergraduate to full professor. The course should accommodate 48 students total. We encourage all students to bring their own specimens for data collection, and to bring old data for the data-reduction and structure-solving tutorials. Please read the Course Announcement at http://www.bnl.gov/RapiData/. You'll see that many experts in the field will be available for lectures and tutorials. You'll find the application materials on the Course Application tab at this site. For the tenth time we will hold a short lecture course on the fundamentals of crystallography for roughly five hours on Sunday 22 April. The body of the RapiData course really requires that students have a healthy knowledge of crystallography. For potential students who have some experience but are shaky about fundamentals, this course will help. There will be a small additional fee for the fundamentals course, to pay for Saturday night accomodations and food on Sunday morning and noon. Latin American Scientists: Several scholarships are available, from the International Union of Crystallography, to pay partial travel and subsistence costs for Latin-American students and junior faculty (under 40 yrs). Please apply for the course, and then contact R. Sweet (sweet(a)bnl.gov) if you are interested in applying for a scholarship. In accordance with the standards of the International Union of Crystallography, we observe the basic policy of non-discrimination, affirming the right and freedom of scientists to associate in international scientific activity without regard to such factors as citizenship, religion, creed, political stance, ethnic origin, race, colour, language, age, or gender, in accordance with the Statutes of the International Council for Science. At this course no barriers will exist beyond the application procedure that would prevent the participation of bona fide scientists. Please apply or send your students to our course, Bob Sweet, Sonya Kiss, and Alex Soares Course Announcement at http://www.bnl.gov/RapiData/ ========================================================================= Robert M. Sweet E-Dress: sweet(a)bnl.gov Group Leader, PXRR: Macromolecular ^ (that's L Crystallography Research Resource at NSLS not 1) http://px.nsls.bnl.gov/ Biology Dept Brookhaven Nat'l Lab. Phones: Upton, NY 11973 631 344 3401 (Office) U.S.A. 631 344 2741 (Facsimile) =========================================================================

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phosphate stereochemistry
by Luca Pellegrini 21 Jan '12

21 Jan '12

Hi, I have noticed that Phenix mangles O-P bond lengths and angles in the phosphate groups of my DNA chain (example in pict attached). This only happens to 3 out of 28 phosphates. The refined protein-DNA structure does not present any other unusual stereochemistry issues and refinement runs normally. Could anybody advice on what is going on and how to fix this, please? I am using Phenix-1.7.3-928. Refinement is with default target weights, hydrogens on and does not include simulated annealing. I could make the stereochemistry targets more stringent, but the default values seem strict enough (bond and angle rmsd is 0.005 and 1.225). Thanks, Luca Luca Pellegrini Department of Biochemistry University of Cambridge 80 Tennis Court Road Cambridge CB2 1GA - UK Email: lp212(a)cam.ac.uk Tel: 0044-1223-760469 Fax: 0044-1223-766002 Sanger building, room 3.59

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phenix.refine is auto selecting an old .pdb file for refinement
by Andrews, Forest Hoyt 21 Jan '12

21 Jan '12

I'm having a bit of an issue with phenix.refine. I was receiving the following error "number of groups of duplicate atom labels: 4789 total number of affected atoms: 9578" However when I looked inside my .pdb file there where only 4789 atoms total....No duplicates. I discovered that phenix.refine is auto selecting a .pdb from a previous run. I found this out by not selecting any .pdb file and found phenix.refine refining my data with an older model I use to refine a previous round. How can I stop phenix.refine from auto selecting a .pdb during refinement? __________________________________ From: phenixbb-bounces(a)phenix-online.org [phenixbb-bounces(a)phenix-online.org] on behalf of Pavel Afonine [pafonine(a)lbl.gov] Sent: Friday, January 20, 2012 12:20 PM To: PHENIX user mailing list Subject: Re: [phenixbb] phosphate stereochemistry Hi Luca, what kind of NCS restraints did you use: torsion or Cartesian? I wonder if torsion NCS would naturally avoid this problem? I hope Jeff comments on this. Pavel On 1/14/12 10:51 AM, Luca Pellegrini wrote: > I think I discovered what was happening to my DNA molecule during > refinement, that caused distortion of the phosphate groups. It was > something along the lines of what Dale suggested, I mention it here so > that it might be useful to others. > > I have two DNA molecules in the ASU and I didn't realised that I had > accidentally swapped OP1 and OP2 in 3 out of 28 phosphates (so that, > if the two DNA molecules were superimposed, OP1 ended on top of OP2). > Because I had NCS restraints on during refinement, I guess phenix was > trying to move OP1 in one DNA molecule towards the NCS-equivalent > position of OP1 in the second molecule, hence the altered geometry. > > I have fixed the atom nomenclature problem and now the geometry of my > DNA is ok. I appreciate that most people tend to avoid such mistakes > ;-) but perhaps it would be good if phenix could flag situations such > as these. > > Luca > > On 6 Jan 2012, at 16:15, Pavel Afonine wrote: > >> Hi Luca, >> >> phenix.refine always generates a *.geo file that lists all the >> geometry restraints (bonds, angles, planarities, chiralities, >> dihedral, non-bonded, ncs(if any)) used in refinement for all atoms. >> For each restraint it list current model value, target (library) >> value, etc. >> >> Can you have a look at *.geo file for O-P bonds in question? May be >> this gives a hint about what's going on? >> >> Pavel >> >> On 1/6/12 4:31 AM, Luca Pellegrini wrote: >>> >>> Hi, >>> >>> I have noticed that Phenix mangles O-P bond lengths and angles in >>> the phosphate groups of my DNA chain (example in pict attached). >>> This only happens to 3 out of 28 phosphates. The refined protein-DNA >>> structure does not present any other unusual stereochemistry issues >>> and refinement runs normally. Could anybody advice on what is going >>> on and how to fix this, please? >>> >>> I am using Phenix-1.7.3-928. Refinement is with default target >>> weights, hydrogens on and does not include simulated annealing. I >>> could make the stereochemistry targets more stringent, but the >>> default values seem strict enough (bond and angle rmsd is 0.005 and >>> 1.225). >>> >>> Thanks, >>> Luca _______________________________________________ phenixbb mailing list phenixbb(a)phenix-online.org http://phenix-online.org/mailman/listinfo/phenixbb

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Real_space_refinement at low resolution question
by fulvio saccoccia 20 Jan '12

20 Jan '12

Dear phenix users, I was wondering if it could be correct to exclude the real_space_refinement step working with a 3.3 A resolution map: I noted that in every real_space_refinemet step phenix told me that it was not useful. How can I exclude the routine from the command line? I am using 1.7.3-928 version.

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