- phenixbb - phenix-online.org

estimated coordinate error
by Jianghai Zhu 01 Aug '07

01 Aug '07

Hi, I am refining a 2.6 A structure using both phenix.refine and refmac5. Both programs give me similar R and Rfree values. But the estimated coordinate errors are quite different. From phenix.refine: maximum likelihood estimate for coordinate error: 0.42 A From refmac5: estimated overall coordinate error: ESU based on R value: 0.427 A ESU based on Free R value: 0.293 A ESU based on maximum likelihood: 0.239 A I am wondering why they are different. Jianghai +++++++++++++++++++++++++++++++ Jianghai Zhu, Ph.D CBR Institute for Biomedical Research Department of Pathology Harvard Medical School 200 Longwood Ave., Boston, MA 02115 Ph: 617-278-3211 Fx: 618-278-3232 +++++++++++++++++++++++++++++++

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General Question !!!
by john kryst 01 Aug '07

01 Aug '07

Hi all !! Please bare with me.. one general very basic question. Do we use electrostatic charges in x-ray refinement. regards John

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AutoSol problem
by Ben Eisenbraun 31 Jul '07

31 Jul '07

Hi- One of my users is running the Linux 64-bit version of Phenix-1.3b and they are getting the following message at the end of their logfile: ************************************************************ Failed to carry out AutoSol_scale_and_analyze_mad: None of the solve versions worked ************************************************************ The solve part of Phenix looks like it built correctly: $ ls -l phenix-1.3b/build/intel-linux-2.6-x86_64/solve_resolve/exe/ -rwxr-xr-x 1 sbgrid sbgrid 1561344 Jun 27 16:55 extract_segment -rwxr-xr-x 1 sbgrid sbgrid 1561344 Jun 27 16:55 extract_segment_pair -rwxr-xr-x 1 sbgrid sbgrid 3483160 Jun 27 16:55 resolve -rwxr-xr-x 1 sbgrid sbgrid 3483576 Jun 27 16:55 resolve_extra_huge -rwxr-xr-x 1 sbgrid sbgrid 3483256 Jun 27 16:55 resolve_giant -rwxr-xr-x 1 sbgrid sbgrid 3482968 Jun 27 16:55 resolve_huge -rwxr-xr-x 1 sbgrid sbgrid 1768392 Jun 27 16:55 resolve_pattern -rwxr-xr-x 1 sbgrid sbgrid 1768392 Jun 27 16:55 resolve_pattern_extra_huge -rwxr-xr-x 1 sbgrid sbgrid 1768392 Jun 27 16:55 resolve_pattern_giant -rwxr-xr-x 1 sbgrid sbgrid 1768392 Jun 27 16:55 resolve_pattern_huge -rwxr-xr-x 1 sbgrid sbgrid 1547840 Jun 27 16:55 segment_library -rwxr-xr-x 1 sbgrid sbgrid 1575648 Jun 27 16:55 side_chains -rwxr-xr-x 1 sbgrid sbgrid 1566208 Jun 27 16:55 side_chains_update -rwxr-xr-x 1 sbgrid sbgrid 5327984 Jun 27 16:55 solve -rwxr-xr-x 1 sbgrid sbgrid 11331152 Jun 27 16:55 solve_extra_huge -rwxr-xr-x 1 sbgrid sbgrid 6529136 Jun 27 16:55 solve_giant -rwxr-xr-x 1 sbgrid sbgrid 7729424 Jun 27 16:55 solve_huge -rwxr-xr-x 1 sbgrid sbgrid 11393392 Jun 27 16:55 solve_mx $ file phenix-1.3b/build/intel-linux-2.6-x86_64/solve_resolve/exe/solve phenix-1.3b/build/intel-linux-2.6-x86_64/solve_resolve/exe/solve: ELF 64-bit LSB executable, AMD x86-64, version 1 (SYSV), for GNU/Linux 2.4.0, statically linked, for GNU/Linux 2.4.0, stripped We do have a standalone Solve install with its corresponding SOLVEDIR, etc, environment variables. Could that be confusing Phenix? I have the complete logfile, but it's rather long. If it would help, it can be made available. Any ideas on what I should do to troubleshoot this? Thanks. -ben -- Ben Eisenbraun Structural Biology Grid http://sbgrid.org/

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TEST - please ignore
by Luca Jovine 31 Jul '07

31 Jul '07

Sorry, just re-testing whether my e-mails to phenixbb are still vanishing into nowhere...

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A question about AutoBuild
by Marcelo Carlos Sousa 30 Jul '07

30 Jul '07

We have solved (in part) a structure by Molecular Replacement. The protein is a homodimer with 360 amino acids per chain (one dimmer per asu). The model was pretty good for the last 220 amino acids or so but appears to be wrong for the first 140 so I deleted them and refined using phenix to an R free of ~ 0.38. As I was about to start model building in O I thought I would give the phenix autobuild a try. The resolution is 2.5 Å and the map shows buildable features for the missing domain. I ran the autobuild wizard with RESOLVE building “in- place” to extend the current model. However the program seemed unable to add fragments of secondary structure (even as alanines) to the model. The question is: is the building “in-place” restricted to “growing” the current model from the ends? Marcelo

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part II. A question about autobuild
by Marcelo Carlos Sousa 30 Jul '07

30 Jul '07

I also noticed that water molecules are assigned to the buildable parts of the map.

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R-factor problem !!!
by john kryst 30 Jul '07

30 Jul '07

Hi all !! I am using phenix.refine to refine my 3.2 A structure. Also i use xtal_pdbsubmission utility in CNS to generate pdb file which is submission ready format. Please note no refinement in CNS only formating. Phenix.refine gave a R and Rfree of 0.1929 & 0.2512 ( rmsd bonds = 0.006) respectively. When i format in CNS it gave R and Rfree 0.2282 & 0.2794 ( rmsd bonds= 0.010865 ). Am i doing any mistake ?? As for as i know we cant generate a submission ready PDB format from phenix.refine. Is it possible to implement it, which will be very helpful for all of us. Thanks in advance for your inputs regards John

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problems with clashes
by Lari Lehtio 30 Jul '07

30 Jul '07

Hi, I nowadays use phenix.refine almost always in the first stages of the refinement and later usually move to refmac. Now I have two modest resolution structures which behave much better in phenix than in refmac. In addition to the more tedious deposition (I guess), I have a problem with clashes. When I analyse the structures with molprobity, I get much better clashscores with refmac refined files. Is there a way to increase the restraint for these contacts or should I just keep decreasing the wxc_scale (from the default)? Rmsds reported by refmac (0 cycles) for bonds and angles are already lower than what I'm used to. B-factors on the other hand seem to be less restrained in phenix. ~Lari~ _______________________________________ Lari Lehtiö Structural Genomics Consortium Medical Biochemistry & Biophysics Dept. Karolinska Institute Stockholm, Sweden _______________________________________

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Re: [phenixbb] ramachanran plot refinement or restraint?
by Ralf W. Grosse-Kunstleve 27 Jul '07

27 Jul '07

Hi Jianghai, > I tried "discard_psi_phi=False" in phenix.refine. There is only > slightly improvement in the R, Rfree, and ramachandran plot (about > 0.2% less disallowed residues, wxc_scale=0.2). A structure > optimization (wxc_scale=0) with the phi-psi restraints has a bigger > impact (about 2% less disallowed residues) with about 2% higher > Rfree. Thanks for your feedback! > What do you think is a good value for wxc_scale in a low-resolution > refinement? This is a tough one to answer. wxc_scale reflects how much you trust your data to guide you to the best model. That depends on many influences. I think the best - although expensive - approach is to simply try a range of values. Note that the esd on the psi-phi restraints are just someone's (?) best guesses. It may be worth playing with these values as well. For that, copy the data_link_TRANS, data_link_PTRANS, data_link_CIS, and data_link_PCIS blocks from mon_lib_list.cif to a new files, change the values, then specify the file on the phenix.refine command line. (You may want to double-check in the .geo file that your new values are actually used.) > What is the difference between wxc_scale=0 and > phenix.geometry_minimization? Should basically be the same, but in phenix.refine you can override parameters like discard_psi_phi. phenix.geometry_minimization doesn't allow you to do this (it is one of those many little things I never got to). Ralf

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Re: [phenixbb] ramachanran plot refinement or restraint?
by Ralf W. Grosse-Kunstleve 26 Jul '07

26 Jul '07

Hi Jianghai, > I am refining a low resolution huge protein structure. There are > about 20% residues in the disallowed region of ramachandran plot. Is > there a way in phenix.refine to refine the phi, psi angles to get a > better ramachandran plot? or a phi, psi restraints in refinement? If you add discard_psi_phi=False to the phenix.refine command line the psi and phi dihedral angles are restraint according to the CCP4 monomer library definitions in mon_lib_list.cif (run phenix.where_mon_lib_list_cif to get the full path name). Look for data_link_TRANS and data_link_CIS, scroll down to _chem_link_tor.value_angle, to see the restraint definitions. We don't have much experience using the phi, psi restraints. If you don't mind, please let us know how it goes! Ralf

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ramachanran plot refinement or restraint?
by Jianghai Zhu 26 Jul '07

26 Jul '07

Hi, I am refining a low resolution huge protein structure. There are about 20% residues in the disallowed region of ramachandran plot. Is there a way in phenix.refine to refine the phi, psi angles to get a better ramachandran plot? or a phi, psi restraints in refinement? Thanks. Jianghai +++++++++++++++++++++++++++++++ Jianghai Zhu, Ph.D CBR Institute for Biomedical Research Department of Pathology Harvard Medical School 200 Longwood Ave., Boston, MA 02115 Ph: 617-278-3211 Fx: 618-278-3232 +++++++++++++++++++++++++++++++

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problems in installation of phenix
by tara kashav 25 Jul '07

25 Jul '07

Dear all, I am trying to install phenix but getting following error. My system specifications are: 2.6.5-1.358 i686. Can anyone suggest me how to troubleshoot and install the program. Traceback (most recent call last): File "/usr/local/phenix-1.3b/phenix/wxGUI/wxPhenix.py", line 11, in <module> import wx File "/usr/local/phenix-1.3b/build/intel-linux-2.6 /base/lib/python2.5/site-packages/wx-2.8-gtk2-ansi/wx/__init__.py", line 45, in <module> from wx._core import * File "/usr/local/phenix-1.3b/build/intel-linux-2.6 /base/lib/python2.5/site-packages/wx-2.8-gtk2-ansi/wx/_core.py", line 4, in <module> import _core_ ImportError: libXfixes.so.3: cannot open shared object file: No such file or directory Thanks, Tara Kashav, Dr. S. Gourinath's Lab, Lab No 430, School of Life Sciences, Jawaharlal Nehru University, New Delhi - 110067

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Re: [phenixbb] How to keep a custom bond planar ?
by Ralf W. Grosse-Kunstleve 24 Jul '07

24 Jul '07

Hi Mathieu, Also sorry for the late reply. > How can I define a plan or some dihedral ?? Sorry, this is not implemented (not hard, but never got to it). > Or as in the ligand .cif I defined a plan > LIG plan-2 C1 0.020 > LIG plan-2 C2 0.020 > LIG plan-2 C3 0.020 > > I could add the atoms NZ and CE of the lysine to the plan-2. You can define the bond, angles, dihedrals, chiralities and planarities with a cif link. Currently we don't generate such links automatically (it is in the works). To get a start, copy one of the links from the mon_lib_list.cif file; the command phenix.where_mon_lib_list_cif will give you the absolute path. Give the cif link a unique name and modify it for your situation. Then use "apply_cif_link" as described in the phenix.refine documentation, e.g. at the CCI Apps download page (http://www.phenix-online.org/download/cci_apps/). Let me know if you need more specific help. Ralf

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Re: [phenixbb] handling of alternate conformations
by Ralf W. Grosse-Kunstleve 24 Jul '07

24 Jul '07

Hi Ulrich, Sorry for the late reply. I was out of town for a week. > My first question is whether NCS constraints are also applied to alternate > conformations. Should be, but is not heavily tested. All NCS restraints are listed in the .geo file created by phenix.refine (assuming write_geo_file=True, which is the default). Look for the long lists following "NCS restraint group". Do your alternative conformation atoms appear in these lists? > My second question concerns the atom count of the conformers, where the > parts with non-alternating conformations seem to be included as well. Pavel's explanation from last week is correct. Internally a "conformer" is always a complete chain. The bond, angle, dihedral, chirality, and planarity restraints are determined independently for each conformer. This generates duplicate restraints which are checked for consistency and then reduced again. Ralf

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handling of alternate conformations
by Ulrich Baumann 16 Jul '07

16 Jul '07

Dear Phenix experts, we encounter the following "problem" when trying to refine alternating conformations: we have a complex with 4 chemically different polypeptide chains in the asymmetric unit, composition A3B3CD. For chains C and D we see additional density, which appears to belong to three alternating conformations which can be thought as rigid-body motions (for the whole chains C and D, let's call these conformers 1,2 and 3, but we label them conventionally in the file with the prefix A,B,and C) with roughly estimated occupancies of about 0.3, 0.3 and 0.4 (we can really see most of them). A and B have no visible alternating conformations (occupancies set to 1.0). From the atom count it appears that phenix reads in three conformers called A,B and C with A: A3B3C(1)D(1), B: A3B3C(2)D(2) and C: A3B3C(3)D(3). Phenix.refine says it has these 3 conformers: conformer A A:2700 atoms, conformer B:2700 atoms, common with A 2100, conformer C:2700 atoms, common with A 2100, common with B 2100. Refinement yields an R/Rfree of about 0.210/0.325. If we treat the three conformers of polypeptide chains C and D as independent chains with occupancy each 1.0 (this is possible 'cos there are no repulsive contacts between them, fortunately), we get R/Rfree of 0.243/0.291 and phenix applies NCS restraints to all chains. The resolution is about 2.9 A. We use phenix.refine from the CCI_APPS, version 2007-03-26-1903, SUSE Linux. My questions is: is the difference due to the lack of NCS between conformers or are the occupancies mistreated somwhow? I am asking because I would not consider the whole A3B3C(x)D(x) particle as a conformer but only chains C and D ...... Is there a possibility to apply NCS restraints to conformers? Many thanks in advance, Ulrich

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How to keep a custom bond planar ?
by Coincon Mathieu 16 Jul '07

16 Jul '07

Hi, I defined a bond (and angles) between my ligand and the NZ of a lysine in a file (bond.def). ..-C2-.. | -CE-NZ = C1-C3-.... This is a double bond. Everything work good except for the planarity of the lysine's atoms. For the bond I wrote in my bond.def: bond { action = *add atom_selection_1 = chain D and resname LIG and name C2 atom_selection_2 = chain A and resname LYS and resid 66 and name NZ distance_ideal = 1.340 sigma = 0.02 } For an angle: angle { action = *add atom_selection_1 = chain D and resname LIG and name C3 atom_selection_2 = chain D and resname LIG and name C2 atom_selection_3 = chain A and resname LYS and resid 66 and name NZ angle_ideal = 120.000 sigma = 3 } How can I define a plan or some dihedral ?? Or as in the ligand .cif I defined a plan LIG plan-2 C1 0.020 LIG plan-2 C2 0.020 LIG plan-2 C3 0.020 I could add the atoms NZ and CE of the lysine to the plan-2. Thanks by advance. And by the way phenix (with coot) is GREAT (I did my apo-enzyme in four days !!!!) -------- Mathieu Coicon PhD Student Biochimie Universite de Montreal (+1)514-343-6111 #5352

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Phaser
by john kryst 13 Jul '07

13 Jul '07

Hi all !!! Is it possible to fix one domain and search for the second one in phaser !!! What are the keywords to use for that. I have a protein with two domains. It i give both the domains together it is not finding the solution. If i give only one domain it is giving the solution and the R and Rfee is 28 and 33. But it is not finding the second one. Thanks in advance for your suggestions.. regards John

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Refinement use of Friedel pairs
by Mark A Saper 11 Jul '07

11 Jul '07

I am refining a structure containing SeMet with data collected at peak wavelength. Provided I give the f' and f'', will phenix.refine calculate F+ and F- structure factors and use the provided FOBS+ and FOBS- ? CNS does this. Refmac only uses f' and I get >6 sigma Fo-Fc peaks on the Se. Thanks for your help. _________________________________ Mark A. Saper, Ph.D. Associate Professor of Biological Chemistry Biophysics Research Division, University of Michigan 930 N University Ave Ann Arbor MI 48109-1055 U.S.A. saper(a)umich.edu (734) 764-3353 fax (734) 764-3323 http://www.biochem.med.umich.edu/biochem/research/profiles/saper.html

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setting resolution for 2 datasets in AutoSol
by Thomas C. Terwilliger 09 Jul '07

09 Jul '07

Hi Luca, It's easiest to do this in 2 steps: 1a. You can set the resolution separately for each dataset in the AutoSol Wizard. In the GUI, just go through each dataset and set the overall resolution to your desired values as you go. Ignore the density modification and building that occurs in this run. 1b. Then you'll get an output exptl_fobs_phases_freeR_flags_2.mtz or equivalent that is phased to the resolution you specified, but that has all the data (with no phases) to higher resolution. 2. Now run the AutoBuild wizard, and set the resolution to your high-resolution limit. That should use the phases you generated, and include the high-res data for density modification and refinement. Equivalently, you can run AutoSol at low resolution then run AutoBuild at higher resolution by supplying an input_hires_file with the hires data. A key point here is that the building in AutoSol is just a preliminary build...the building in AutoBuild is the real thing. You can also run 2 datasets and set the resolution for each in a script. Here is a script to read in 2 SAD datasets and solve them together as one, setting the resolution of phasing to 3 A for the first and 2.9 for the second, cat two_datasets.inp input_seq_file seq.dat resolution 2.9 # Resolution expt_type sad input_file_list se.sca ############## NEW DATASET ################ run_list start # run "start" method. run_list read_another_dataset # starting a new dataset here resolution 3.1 # Resolution input_file_list br.sca Let me know if that does not do it! -Tom T >> From: lp212(a)mole.bio.cam.ac.uk >> Date: July 9, 2007 3:38:28 PM PDT >> To: phenixbb(a)phenix-online.org >> Subject: script for Zn and Se phasing >> Hi, >> I have collected two peak datasets on two different crystals, for a protein that contains zinc: >> 1. peak dataset at the Zn edge (lambda=1.285A, 2.5A reso) >> 2. peak dataset at the Se edge (lambda=0.98A, 2.8A reso) >> The protein has 2 Zn and 11 SeMet, and 4/au. When I input both >> datasets in the AutoSol GUI, Hyss finds correctly 8/8 Zn sites, and ~34/44 Se sites, but only when I cut back the resolution (4.2A for Zn, and 4.7A for Se). What I can't figure out is how to tell the Autosol GUI to use a low-res cutoff for finding the sites, and then use all the data for model building. Could someone please explain how to do this in the GUI, or send me a script? >> Thanks a lot! Apologies if this is trivial... >> Luca >

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Re: [phenixbb] depositing phenix-refined coordinates
by Ralf W. Grosse-Kunstleve 05 Jul '07

05 Jul '07

Hi Enrico, > However, I would be very grateful if someone could point me to the topic > already posted in the message below by Dr. Scott few days ago, > exactly at: > "a quick description for depositing phenix-refined coordinates?", > though the full message contained very interesting points I would > love to hear about We don't have a dedicated deposition tool yet, sorry. But we are actively working with the PDB on this. In the meantime, the .pdb files produced by phenix.refine are the best starting point. > (I also performed refinement by refmac/phenix, and observed kind of a > similar trend for those numbers). It may be because we are reporting mean deviations instead of root-mean-square deviations. This is kind of an oversight on our part and will be changed in the next version. Ralf

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CCI-Apps Verisons vs. Phenix Versions
by Schubert, Carsten [PRDUS] 05 Jul '07

05 Jul '07

Hi, Quick question about versions of CCI-Apps as standalones and in phenix. How does once decide which version of the CCI-Apps is more current? I have not looked in depth, but is there a equivalent build tag for the CCI-Apps in phenix as the one for the CCI-Apps. Currently I am assuming that the CCI-Apps are alway more up to date, but that may not hold true for the upcoming phenix 1.3 release. Thanks Carsten

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some general refine questions
by William Scott 04 Jul '07

04 Jul '07

Hi folks: With the helpful advice of the phenix crew, I've re-refined 2goz, an entry in the pdb in which I used refmac5 the first time around. There was a small error in the pdb: One nucleotide (C8 in chain A) was rotated 180 degrees about the glycosylic bond from where it should have been. The net result is one oxygen atom was in the wrong place in the structure, and this was apparent within the difference Fourier. After I rotated the base and re-refined in refmac, the Rfactor and other stats remained essentially unchanged (so this fix has nothing to do with the following): My refinement results in Refmac: REMARK 3 R VALUE (WORKING SET) : 0.191 REMARK 3 FREE R VALUE : 0.241 REMARK 3 RMS DEVIATIONS FROM IDEAL VALUES COUNT RMS WEIGHT REMARK 3 BOND LENGTHS REFINED ATOMS (A): 1503 ; 0.009 ; 0.021 REMARK 3 BOND ANGLES REFINED ATOMS (DEGREES): 2331 ; 1.676 ; 3.000 Then I refined in phenix. I get REMARK Final: r_work = 0.1737 r_free = 0.2224 bonds = 0.003 angles = 0.745 So the working and free R factor are both lower, and the geometry is substantially tighter. If I relax the weights in phenix, even to get rms bonds of around 0.006, the free-R goes up, which tells me this is not something I am justified in doing. Phil Evans once told me that anything tighter than about 0.01 (conservatively) was science-fiction, in that this is within the error of the idealized libraries for bond lengths. Other people have asked me about this too, and I didn't know how to reply. Is bonds = 0.003 angles = 0.745 realistic, or have I done something wrong? Even if I do structure idealization in Refmac, I can't get the rms bonds below about 0.005 (and my understanding is that it uses the same monomer library). Why is the weight multiplied by 0.5 by default? Since changing that to 1.0 slightly increases freeR, I assume it is the default for some reason. All the best, Bill PS: Could someone point me to a quick description for depositing phenix-refined coordinates? (The latest phenix installer seems to have omitted the docs.) William G. Scott contact info: http://chemistry.ucsc.edu/~wgscott

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Re: [phenixbb] sugar links in phenix.refine
by Ralf W. Grosse-Kunstleve 04 Jul '07

04 Jul '07

Almost, but you need a separate scope (thing between braces) for each link, e.g.: refinement.pdb_interpretation.apply_cif_link { data_link = NAG-ASN residue_selection_1 = chain A and resname NAG and resid 900 residue_selection_2 = chain A and resname ASN and resid 329 } refinement.pdb_interpretation.apply_cif_link { data_link = NAG-NAG-b-D residue_selection_1 = chain A and resname NAG and resid 901 residue_selection_2 = chain A and resname ASN and resid 900 } Or alternatively: refinement.pdb_interpretation { apply_cif_link { data_link = NAG-ASN residue_selection_1 = chain A and resname NAG and resid 900 residue_selection_2 = chain A and resname ASN and resid 329 } apply_cif_link { data_link = NAG-NAG-b-D residue_selection_1 = chain A and resname NAG and resid 901 residue_selection_2 = chain A and resname ASN and resid 900 } } Ralf

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Re: [phenixbb] Multivariate Z score L-test
by Claudia Scotti 29 Jun '07

29 Jun '07

Thank you so much. I'll try all the space groups and see what happens. Many thanks again, Claudia Claudia Scotti Dipartimento di Medicina Sperimentale Sezione di Patologia Generale Universita' di Pavia Piazza Botta, 10 27100 Pavia Italia Tel. 0039 0382 986335/8/1 Facs 0039 0382 303673 ---------------------------------------- > Date: Fri, 29 Jun 2007 07:35:22 -0700 > From: PHZwart(a)lbl.gov > To: phenixbb(a)phenix-online.org > Subject: Re: [phenixbb] Multivariate Z score L-test > > Hi Claudia, > > This could indicate that tyour data is actually P 2 1 1, P 1 2 1 or P > 1 1 2 or P 21 1 1, P 1 21 1, P 1 1 21. Try processing that data in > those spacegroups and see if that makes any difference. You might end > up havig to refine your structure in all spacegroups to find out which > possibility is the best. > > It could also indicate that the quality of your data is not very good, > either due to suboptimal data processing or because of bad diffraction > (or both). > > HTH > > Peter > > > 2007/6/29, Claudia Scotti : > > > > Dear List, > > > > I'm only at my third structure (a scFv antibody fragment) and I'm disturbing about a dataset that is giving problems at the refinement stage: it gets stuck at about Rcryst= 0.36 and Rfree=0.44. > > > > I've tried data processing with several softwares (Mosflm, XDS, Denzo) and the result is consistently P222, unit cell 69x79x90, 90, 90, 90. The data are anisotropic, with limits at 2.3 and 2.8 A. I cut the data at 3.0 A. > > Matthews coefficient suggests two molecules per asu. > > No NCS is detected by self-rotation and a native Patterson detects a small peak (10% of origin peak) at 0.19, 0.34, 0.5. > > MR using several softwares (AmoRe, Molrep and Phaser) and several models all agree that the best space group is P21212, though the systematic absences are not perfectly consistent. > > > > When refining, refinement gets stuck as I mentioned above. > > > > I've run Phenix x-triage and the results include this line (see below): "It could be worthwhile considering reprocessing the data". I was wondering if the Multivariate Z score L-test: 6.305 might suggest how to reprocess the data. > > > > Sorry for the probably trivial question and for probably missing important data. > > > > Thanks a lot for any help and suggestions, > > > > Claudia > > > > ------------------------------------------------------------------------------- > > Twinning and intensity statistics summary (acentric data): > > > > Statistics independent of twin laws > > - /^2 : 1.827 > > - ^2/ : 0.838 > > - : 0.649 > > - , : 0.417, 0.242 > > Multivariate Z score L-test: 6.305 > > The multivariate Z score is a quality measure of the given > > spread in intensities. Good to reasonable data is expected > > to have a Z score lower than 3.5. > > Large values can indicate twinning, but small values do not > > neccesarily exclude it. > > > > > > No (pseudo)merohedral twin laws were found. > > > > > > Patterson analyses > > - Largest peak height : 11.094 > > (correpsonding p value : 1.080e-01) > > > > > > The largest off-origin peak in the Patterson function is 11.09% of the > > height of the origin peak. No significant pseudotranslation is detected. > > > > The results of the L-test indicate that the intensity statistics > > are significantly different then is expected from good to reasonable, > > untwinned data. > > As there are no twin laws possible given the crystal symmetry, there could be > > a number of reasons for the departure of the intensity statistics from normality. > > Overmerging pseudo-symmetric or twinned data, intensity to amplitude conversion problems > > as well as bad data quality might be possible reasons. > > It could be worthwhile considering reprocessing the data. > > ----------------------------------------------------------------------------------------------- > > > > Claudia Scotti > > Dipartimento di Medicina Sperimentale > > Sezione di Patologia Generale > > Universita' di Pavia > > Piazza Botta, 10 > > 27100 Pavia > > Italia > > Tel. 0039 0382 986335/8/1 > > Facs 0039 0382 303673 > > > > _________________________________________________________________ > > Express yourself instantly with MSN Messenger! Download today it's FREE! > > http://messenger.msn.click-url.com/go/onm00200471ave/direct/01/ > > _______________________________________________ > > phenixbb mailing list > > phenixbb(a)phenix-online.org > > http://www.phenix-online.org/mailman/listinfo/phenixbb > > > _______________________________________________ > phenixbb mailing list > phenixbb(a)phenix-online.org > http://www.phenix-online.org/mailman/listinfo/phenixbb _________________________________________________________________ With Windows Live Hotmail, you can personalize your inbox with your favorite color. www.windowslive-hotmail.com/learnmore/personalize.html?locale=en-us&ocid=TX…

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Multivariate Z score L-test
by Claudia Scotti 29 Jun '07

29 Jun '07

Dear List, I'm only at my third structure (a scFv antibody fragment) and I'm disturbing about a dataset that is giving problems at the refinement stage: it gets stuck at about Rcryst= 0.36 and Rfree=0.44. I've tried data processing with several softwares (Mosflm, XDS, Denzo) and the result is consistently P222, unit cell 69x79x90, 90, 90, 90. The data are anisotropic, with limits at 2.3 and 2.8 A. I cut the data at 3.0 A. Matthews coefficient suggests two molecules per asu. No NCS is detected by self-rotation and a native Patterson detects a small peak (10% of origin peak) at 0.19, 0.34, 0.5. MR using several softwares (AmoRe, Molrep and Phaser) and several models all agree that the best space group is P21212, though the systematic absences are not perfectly consistent. When refining, refinement gets stuck as I mentioned above. I've run Phenix x-triage and the results include this line (see below): "It could be worthwhile considering reprocessing the data". I was wondering if the Multivariate Z score L-test: 6.305 might suggest how to reprocess the data. Sorry for the probably trivial question and for probably missing important data. Thanks a lot for any help and suggestions, Claudia ------------------------------------------------------------------------------- Twinning and intensity statistics summary (acentric data): Statistics independent of twin laws - /^2 : 1.827 - ^2/ : 0.838 - : 0.649 - , : 0.417, 0.242 Multivariate Z score L-test: 6.305 The multivariate Z score is a quality measure of the given spread in intensities. Good to reasonable data is expected to have a Z score lower than 3.5. Large values can indicate twinning, but small values do not neccesarily exclude it. No (pseudo)merohedral twin laws were found. Patterson analyses - Largest peak height : 11.094 (correpsonding p value : 1.080e-01) The largest off-origin peak in the Patterson function is 11.09% of the height of the origin peak. No significant pseudotranslation is detected. The results of the L-test indicate that the intensity statistics are significantly different then is expected from good to reasonable, untwinned data. As there are no twin laws possible given the crystal symmetry, there could be a number of reasons for the departure of the intensity statistics from normality. Overmerging pseudo-symmetric or twinned data, intensity to amplitude conversion problems as well as bad data quality might be possible reasons. It could be worthwhile considering reprocessing the data. ----------------------------------------------------------------------------------------------- Claudia Scotti Dipartimento di Medicina Sperimentale Sezione di Patologia Generale Universita' di Pavia Piazza Botta, 10 27100 Pavia Italia Tel. 0039 0382 986335/8/1 Facs 0039 0382 303673 _________________________________________________________________ Express yourself instantly with MSN Messenger! Download today it's FREE! http://messenger.msn.click-url.com/go/onm00200471ave/direct/01/

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