February 2012 - phenixbb - phenix-online.org

links in phenix summary
by Christian Roth 04 Apr '13

04 Apr '13

Dear all, thanks to the phenix team which helped me a lot to resolve all issues regarding the correct link definitions. I have summarised a few things which one might consider if nonstandard links are necessary. Try phenix ready set to get your links out of the pdb. Do not forget to change the possible LINKR to LINK! Inspect the links and decide if they are useful! Peptide links are automatically incorporated if residues are close (inspect geo file) Non standard peptide links could be created using using an now available alpha release script: elbow.ligand_linking model.pdb Inspect the generated cif file and correct angles and incorporate dihedrals and so on if necessary. Sugar links which exists in the mon_lib.cif should be incorporated using the apply_cif link option like refinement.pdb_interpretation.apply_cif_link { data_link = ALPHA1-4 residue_selection_1 = chain B and resname GLC and resseq 1 residue_selection_2 = chain B and resname GLC and resseq 2 } According to the link definition the C1 oxygen of the following sugar with the higher number must be removed. The automatic incorporation of sugar links will be probably soon available in phenix. Nigel is already working on this. If one want use hydrogens in the refinement, they have to be added previously with ready_set and afterwards the OH4 sugar hydrogen has to be removed before the refinement. For links with symmetry related atoms the symmetry operator must be included in a custom bond definition efinement.geometry_restraints.edits { bond { action = *add delete change atom_selection_1 = chain A and resname HEM and resid 154 and name FE atom_selection_2 = chain A and resname MTO and resid 155 and name O symmetry_operation = -x,y,-z distance_ideal = 2.2 sigma = 0.01 } } The operator can be obtained using iotbx.show_distances your.pdb > all_distances Search for keyword "sym" or from Coot clicking on the symm option. Coot print out the operator and the translation term separately. Both has to be merged in the final operator used in phenix! Christian

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How to include restraints when refining DNA?
by Xun Lu 03 May '12

03 May '12

Dear all, I am refining a protein-DNA complex structure at 2.9A resolution. The R/Rfree is 0.2181/0.2501, which is pretty good, but I can tell that the DNA is not well refined. Some sugar puckers are not right. The distances between some base-paired bases are kind of short (~2.5A). I've tried including a reference model for the DNA, or including a cif file, and I've also tried to turn on the secondary_structure_restraints.... nothing worked. I must have not done it in a correct way. But how to do it? And how to deal with sugar puckers? In refmac, I can set the distances between bases during the refinement, so there must be a way to do it in phenix as well? Any advice is welcome. Thanks! Xun -- Department of Molecular and Structural Biochemistry North Carolina State University

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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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Batch conversion
by Theresa H 05 Mar '12

05 Mar '12

Hi all How can I use ADXV to batch conversion of diffraction image to tiff format? Would like to put about 20 of them in Powerpoint slides. Thank you. Theresa

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NCS-averaged and superposed maps
by Mullins, Elwood 29 Feb '12

29 Feb '12

Is it possible to both NCS-average and superpose maps? I can do one or the other easily enough from the command line (phenix.ncs_average) and the GUI (Superpose maps). Unfortunately, both programs require the input to be an mtz file but output ccp4-style maps. I don't see a way to do this sequentially. Is there some other method that would allow me to perform both operations? Thanks, Elwood =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-= Elwood A. Mullins Ph.D. Candidate Department of Chemistry Washington University in St. Louis Campus Box 1134 One Brookings Drive Saint Louis, MO 63130-4899 Email: elwood.mullins(a)wustl.edu Tel: (765) 496-6814 Fax: (765) 494-7897 =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=

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R-free flags
by 刘世恒 29 Feb '12

29 Feb '12

Hi, According to the phenix documentation, phenix.refine generates free R that are evenly distributed over the resolution, making sure that relatively thin resolution bins receive enough of reflections. The default behavior is to flag 5% of reflections up to a maximum of 2000. However,in some high-resolution structure, the percent for R-free test set which was generated by phenix.refine might be smaller than 1%， and it was a small percentage. Are there anticles related to the generation of R-free flag by phenix? Sincerely yours, Shiheng Liu

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adding solvents other than water
by Subhani Bandara 28 Feb '12

28 Feb '12

Hi all, How can I identify atoms like Na+, K+ in the map, from the positive density. Also can I add solvents like MPD and Tris buffer if any. Is there a specific way or do I have to run ligand fit. Is there any material I can read on this. Thanks in advance. Subhani

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Fixing ligand position in refine
by Christopher Wanty 28 Feb '12

28 Feb '12

Hi, I have a problem with a phosphate moving out of position during refinement. The complication is that there is an existing phosphate in the same location as the one I'm trying to place, but the existing one is part of a modified residue, and there is clearly density for the alternative conformation of the phosphate, but it is also clearly not still bound to the residue. How do I make sure that the phosphate does not move away from where it should be? Attached image show the phosphate more or less where I want it, and you should be able to see where the existing phosphate is attached to the residue. The large red density blob is where phenix.refine tried to put the phosphate last time. Kind regards, Chris ------------------------------------------------------- Dr. Christopher Wanty christopher.wanty(a)uwa.edu.au Research Associate Biomolecular, Biomedical and Chemical Sciences, Building M310 University of Western Australia 35 Stirling Highway Crawley 6009 Western Australia Australia

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MSE MET occupancy issue
by Ming 28 Feb '12

28 Feb '12

Hi all, I was trying to refine a protein with phenix.refine. I want to refine AMSE and BMET with occupancies 0.5 and 0.5. What I did is modifying the pdb file by copy the coordinates of MET to MSE, and change the names to be AMSE and BMET, modifying the occupancy to be 0.5 and 0.5 for each one. Everything else like the atom names have been taken care of too. I used the readyset to make sure the pdb file is good. But phenix.refine keeps giving me error saying "numbers of atoms with unknown nonbonded energy type symbols ". Anyone here can help me with this please? Thanks in advance,

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Phenix Error while running refinement
by Subhani Bandara 27 Feb '12

27 Feb '12

Hi everyone, I am getting following error while running phenix refinement for a protein cocrystalized with a metal chelator complex. What could be the problem. AssertionError : Traceback: File "/Applications/PHENIX-1.7.3-928/Contents/phenix-1.7.3-928/cctbx_project/libtbx/thread_utils.py", line 229, in run return_value = self._target(self._args, self._kwargs, self._c) File "/Applications/PHENIX-1.7.3-928/Contents/phenix-1.7.3-928/cctbx_project/libtbx/runtime_utils.py", line 72, in __call__ result = self.target() File "/Applications/PHENIX-1.7.3-928/Contents/phenix-1.7.3-928/phenix/phenix/refinement/runtime.py", line 67, in __call__ call_back_handler=callback) File "/Applications/PHENIX-1.7.3-928/Contents/phenix-1.7.3-928/phenix/phenix/refinement/command_line.py", line 97, in run call_back_handler=call_back_handler) File "/Applications/PHENIX-1.7.3-928/Contents/phenix-1.7.3-928/phenix/phenix/refinement/driver.py", line 1478, in run ncs_manager = self.ncs_manager) File "/Applications/PHENIX-1.7.3-928/Contents/phenix-1.7.3-928/phenix/phenix/refinement/strategies.py", line 344, in refinement_machine model.show_occupancy_statistics(text = "Occupancies statistics", out=log) File "/Applications/PHENIX-1.7.3-928/Contents/phenix-1.7.3-928/cctbx_project/mmtbx/model.py", line 868, in show_occupancy_statistics self.xray_structure.set_occupancies(value=0., selection = less_than_zero) File "/Applications/PHENIX-1.7.3-928/Contents/phenix-1.7.3-928/cctbx_project/cctbx/xray/structure.py", line 480, in set_occupancies assert selection.size() == s.size() Thanks Subhani

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