March 2011 - phenixbb - phenix-online.org

rotamers
by Ed Pozharski 30 Mar '11

30 Mar '11

Does refine restrains side chain rotamers to, say, the closest one from the rotamer dictionary or, perhaps, the starting coordinates (I find this less likely, of course)? I am particularly interested in what would happen if a side chain is disordered and there is no strong electron density to support a specific conformation. Do I understand correctly that the real-space refinement for the side chains is on by default, which means that disordered side chains would tend to stay within their biased density? I apologize if I missed the description of this in the manual, just point me to the right section then. Cheers, Ed. -- "I'd jump in myself, if I weren't so good at whistling." Julian, King of Lemurs

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are the rigid_body group shifts cummulative or stepwise?
by Scott Classen 30 Mar '11

30 Mar '11

i.e. do the translation & rotation values reported in each rigid body step in the log file represent the TOTAL shift from the initial pre-RB model or just the shift for that particular step? Thanks, Scott

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Same enzyme, different space groups ?
by Yuri 29 Mar '11

29 Mar '11

Hello everyone, I was comparing 2 data sets I have and when I run Xtriage I noticed the following: a) for one crystal (data processed in P 4 2 2) | space group | n absent | <Z>_absent | <Z/sigZ>_absent | +++ | --- | score | ------------------------------------------------------------------------------------ | P 41 21 2 | 24 | 0.03 | 1.30 | 0 | 2 | 0.000e+00 | | P 43 21 2 | 24 | 0.03 | 1.30 | 0 | 2 | 0.000e+00 | | P 42 21 2 | 22 | 0.03 | 1.27 | 0 | 4 | 7.187e-02 | | P 4 21 2 | 18 | 0.01 | 1.21 | 0 | 8 | 3.035e-01 | | P 41 2 2 | 6 | 0.11 | 1.59 | 0 | 20 | 9.065e-01 | | P 43 2 2 | 6 | 0.11 | 1.59 | 0 | 20 | 9.065e-01 | | P 42 2 2 | 4 | 0.13 | 1.57 | 0 | 22 | 9.784e-01 | | P 4 2 2 | 0 | 0.00 | 0.00 | 0 | 26 | 1.210e+00 | ------------------------------------------------------------------------------------ b) the other crystal, of the same enzyme (data scaled in P 43 21 2) x triage tells me this crystal is in P 43 21 2. | space group | n absent | <Z>_absent | <Z/sigZ>_absent | +++ | --- | score | ----------------------------------------------------------------------------------- | P 4 2 2 | 0 | 0.00 | 0.00 | 0 | 2 | 0.000e+00 | | P 4 21 2 | 0 | 0.00 | 0.00 | 0 | 2 | 0.000e+00 | | P 41 2 2 | 0 | 0.00 | 0.00 | 0 | 2 | 0.000e+00 | | P 41 21 2 | 0 | 0.00 | 0.00 | 0 | 2 | 0.000e+00 | | P 42 2 2 | 0 | 0.00 | 0.00 | 0 | 2 | 0.000e+00 | | P 42 21 2 | 0 | 0.00 | 0.00 | 0 | 2 | 0.000e+00 | | P 43 2 2 | 0 | 0.00 | 0.00 | 0 | 2 | 0.000e+00 | | P 43 21 2 | 0 | 0.00 | 0.00 | 0 | 2 | 0.000e+00 | ----------------------------------------------------------------------------------- My understanding is that P 43 21 2 should have 0 systematic absences (if I am wrong, please point it out) My questions are: what is really my space group? Or should I say space groups, if indeed I have two different space groups. How do I nterpret the scores? Could it all be a function of the space group they were processed in? -- Yuri Pompeu

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Target weight optimization (wxu_scale and wxu)
by Zhang yu 28 Mar '11

28 Mar '11

Dear Phenixer, What is the real meaning of the 'wxu_scale' and 'wu'? (scale factor for X-ray/ADP_weight: wxu_scale ADP weight scale: wu) During ADP refinement, it is suggested to refine the 'wxu_scale', what if I change the value of 'wu'? Thanks Yu

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Split Occupancy of a ligand and water
by Brandon Goblirsch 28 Mar '11

28 Mar '11

Hello, Currently I am have a structure which has a ligand bound at less than full occupancy. The ligand in this cause is covalently linked to a CYS residue in the enzyme active site. When the ligand is not present, there are two well conserved waters in the active site in its place. Overall, I have a same space, split occupancy issue. The problem I am having now in phenix 1.7.460 is that I want to refine (simultaneously) these water positions superimposed on the bound ligand position (as both have less than 100% occupancy). However, upon refinement, the waters are always "kicked out" of position and are not allowed to overlay with atoms within the bound ligand. Does anyone know how to get phenix.refine to accept the water and ligands occupying the same coordinate space. Obviously setting the ligand and water positions to sub 100% occupancy does not do the trick. Thanks for any help!! Brandon -- Brandon Goblirsch Research Assistant-Wilmot Lab Biochemistry, Molecular Biology and Biophysics 5-230 Nils Hasselmo Hall Minneapolis, MN 55455 (612)624-0141

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anomalous difference map
by Jason 28 Mar '11

28 Mar '11

Hello Everyone, I have an old question about how to create anomalous difference map. Facts: 1) Synchrotron Fluorescence scan indicates the heavy atom definitely presents in my protein (my control is a second protein with the same ligand showed no absorbance spectrum) 2) xds processed mtz file 3) Data resolution ~ 3 angstron 3) molecular replacement solved apo structure protein.pdb using phenix.refine 4) phenix.maps to generate anomalous map (phenix.refine will also generate it, but let's leave it aside for the moment) Questions: When I load the mtz file to phenix.maps GUI, the mtz label pulldown menu indicates 4 possible choices for the column to use:(1) IMEAN, SIGIMEAN (2) I(+), sigI(+), I(-), sigI(-) merged (3) F(+), sigF(+), F(-), sigF(-) merged (4) F, sigF, Dano SigDano. I have tried the choices of (2) (3) and (4). However, there is barely any anomalous signal at 4sigma, which makes me wondering if something is not right. The first thing coming to my mind is the mtz labels: I(+), sigI(+), I(-), sigI(-) merged. What does merged mean? Could this be the reason? Other issues that could causing the trouble? Thank you all. ====================== Jason Structural Biology Department University of Pittsburgh ======================

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secondary structure restraints
by Bradley Hintze 28 Mar '11

28 Mar '11

Hello PHENIX developers. When I run phenix.secondary_structure_restraints 1ZY7.pdb format=refmac I get this error: Traceback (most recent call last): File "/Users/bradleyhintze/phenix/phenix-dev-699/cctbx_project/mmtbx/command_line/secondary_structure_restraints.py", line 6, in <module> secondary_structure.run(sys.argv[1:]) File "/Users/bradleyhintze/phenix/phenix-dev-699/cctbx_project/mmtbx/secondary_structure/__init__.py", line 766, in run if (len(proxies) == 0) : NameError: global name 'proxies' is not defined Am I missing something? Also, is there anything like '-h' on phenix.secondary_structure_restraints so that I can figure out the different options? Thanks, Bradley

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differences between command line and GUI?
by Kendall Nettles 28 Mar '11

28 Mar '11

Dear PHENIX developers, I ran a job through the GUI, and then what I thought was the same job on our cluster. The job from the cluster has Rfree that is 0.7% higher. I'm totally at a loss to figure out what is causing this. It is the same version of PHENIX (1.7-650). I then took the .eff file from the GUI job and used that as the params file for the command line job but still get the big difference in R free. Any suggestions? Best regards, Kendall Nettles

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r_free_flags.export_for_ccp4 option of iotbx.reflection_file_editor
by Keitaro Yamashita 26 Mar '11

26 Mar '11

Dear PHENIX developers, I'm using phenix-1.7-650 (current latest). I noticed that r_free_flags.export_for_ccp4 option of iotbx.reflection_file_editor, which convert flag convention to ccp4 style, does always assign 1..19 to working set at random. In CCP4 style, I think working set flag numbers should be 1 .. (1 / fraction - 1). Otherwise, I'm afraid it might have a bad influence on further processing e.g. flag value completion using ccp4 program. I look forward to your response, Keitaro

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modified nucleotide not linked
by tuske＠cabm.rutgers.edu 25 Mar '11

25 Mar '11

Hello all, I am refining three protein-DNA complexes each with a different modified nucleotide-monophosphate residue at the 3'-terminus of its DNA strand. Two of these worked fine after sending the pdb file through ready-set. With the third structure the modified nucleoside-monophosphate residue is not recognized as linked to the previous nucleotide-monophospahe--no phosphodiester bond formation. The only difference between the two that "worked" and the one that didn't is the nature of the deoxyribose sugar modification. The first two have substituents at the 4'-carbon of the deoxyribose sugar, the third has the 4'-oxygen of the deoxyribose sugar substituted with a -CH2- making it a cylcopentyl pseudo-sugar. The bond lengths and angles are reasonable in the starting model, I had no problem doing the initial refinement in CNS after defining topology and parameter files. The output for this in the log file is: Chain: "P" Number of atoms: 439 Number of conformers: 1 Conformer: "" Number of residues, atoms: 21, 439 Unusual residues: {'CAR': 1} Classifications: {'undetermined': 1, 'DNA': 20} Modifications used: {'5*END': 1} Link IDs: {None: 1, 'rna3p': 19} Not linked: pdbres="CYT P 821 " segid="P " pdbres="CAR P 822 " segid="P " Thanks, Steve

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