June 2013 - phenixbb - phenix-online.org

EG4 not in phenix dictionary?
by Yarrow Madrona 03 Jun '13

03 Jun '13

Hello, I have previously refined EG4 and EG2 (tetra and diethylene glycol) as ligands and these were in the standard phenix library. I was under the impression that phenix shares the library from the CCP4 monomer library which I know should have EG4. Can anyone help me with this. I guess the alternative is to generate a restraints file. -Yarrow -- Yarrow Madrona Graduate Student Molecular Biology and Biochemistry Dept. University of California, Irvine Natural Sciences I, Rm 2403 Irvine, CA 92697

2 1

MAX IV Life Science Director position
by Derek Logan 03 Jun '13

03 Jun '13

Hi, If anyone fancies becoming Life Science Director at the world's brightest light source, look no further than here: http://www.lunduniversity.lu.se/o.o.i.s?id=24914&Dnr=547454&Type=E /Derek ________________________________________________________________________ Derek Logan tel: +46 46 222 1443 Associate Professor mob: +46 76 8585 707 Dept. of Biochemistry and Structural Biology www.cmps.lu.se<http://www.cmps.lu.se> Centre for Molecular Protein Science www.maxlab.lu.se/node/307<http://www.maxlab.lu.se/node/307> Lund University, Box 124, 221 00 Lund, Sweden

1 0

Re: [phenixbb] Discrepancy between R-factors from phenix.refine vs phenix Generate "Table 1"
by Michael Thompson 01 Jun '13

01 Jun '13

As another follow up to this point, I have had a recent example where Xtriage reported that my intensity statistics indicated twinning (<|L|>=0.399 and <L^2>=0.227, alpha=0.4). After having refined the structure with the suggested twin law, and making composite omit maps along the way (using autobuild with no twin law), I ran model vs. data at the end of refinement and noticed that it reported R/Rfree that were about 10% higher than the R/Rfree from refinement, similar to what the original post described. I checked the model vs. data logfile and found that the L-test routine used by model vs. data was failing, so the subsequent analysis was carried out as if there was no twinning. So in my case, the crystal was twinned, but model vs. data was not able to perform the L-test so it was outputting incorrect R-factors. The error message at the top of the model vs. data log file is: Twin analysis failed: Python argument types in l_test.__init__(l_test, miller_index, double, space_group, bool, float, float, float, int) did not match C++ signature: __init__(_object*, scitbx::af::const_ref<cctbx::miller::index<int>, scitbx::af::trivial_accessor> miller_indices, scitbx::af::const_ref<double, scitbx::af::trivial_accessor> intensity, cctbx::sgtbx::space_group space_group, bool anomalous_flag, long parity_h, long parity_k, long parity_l, unsigned long max_delta_h) Twin analysis failed: Python argument types in l_test.__init__(l_test, miller_index, double, space_group, bool, float, float, float, int) did not match C++ signature: __init__(_object*, scitbx::af::const_ref<cctbx::miller::index<int>, scitbx::af::trivial_accessor> miller_indices, scitbx::af::const_ref<double, scitbx::af::trivial_accessor> intensity, cctbx::sgtbx::space_group space_group, bool anomalous_flag, long parity_h, long parity_k, long parity_l, unsigned long max_delta_h) Perhaps there are some other users who are seeing this behavior because the L-test fails within model vs. data. Mike ----- Original Message ----- From: "Nathaniel Echols" <nechols(a)lbl.gov> To: "PHENIX user mailing list" <phenixbb(a)phenix-online.org> Sent: Wednesday, May 29, 2013 5:18:57 PM GMT -08:00 US/Canada Pacific Subject: Re: [phenixbb] Discrepancy between R-factors from phenix.refine vs phenix Generate "Table 1" On Wed, May 29, 2013 at 4:13 PM, Sam Stampfer <Samuel.Stampfer(a)tufts.edu> wrote: > When I refined my model in phenix, I used the twin law h,-h-k,-l. I read in > the documentation that twinning can account for some of this discrepancy, > but that the program is supposed to take twinning into account if it will > lower the calculated R-work by more than 2%, which it doesn't seem to have > done (or there is some other problem with my data). Okay, the problem is that your data don't actually appear to be twinned. The automatic method used by phenix.model_vs_data (which is used internally for Table 1 and the validation GUI) only tries possible twin laws if the results of the "L test" show a suspicious distribution of intensities. Your data look fine, so it doesn't bother trying the twin laws. That the R-factors are lower when you refine with a twin law isn't necessarily indicative of the data actually being twinned - Garib Murshudov has looked into this in detail but I confess to being ignorant of the math (but I can probably dig up his paper on the subject if anyone is interested). However, I'm pretty sure the data are actually in a higher-symmetry space group. Will send details and new files off-list (probably tomorrow at this rate). I should probably change some of the programs and/or documentation to make it more clear what is being done internally, since it took me a bit of digging to realize what was going on. In general, though, always be very careful before running twinned refinement! I have seen several users do this by mistake when they really had higher symmetry. The maps will also be more model-biased when using twinned refinement, so it's good to avoid doing this unless absolutely necessary. -Nat _______________________________________________ phenixbb mailing list phenixbb(a)phenix-online.org http://phenix-online.org/mailman/listinfo/phenixbb -- Michael C. Thompson Graduate Student Biochemistry & Molecular Biology Division Department of Chemistry & Biochemistry University of California, Los Angeles miket(a)chem.ucla.edu

4 4