- phenixbb - phenix-online.org

Phaser SAD module - resolution question
by Peter Grey 13 Aug '10

13 Aug '10

Dear Phenix community, I am using Phaser SAD module with a poor MR model to locate the initial heavy-atom sub-structure. I have a 3A dataset but the anomalous signal is weak at the higher resolution shells. I would like to ask for your advice regarding the resolution I should use in Phaser. I thought that for the sake of just locating the sites I should use relatively low resolution (let's say 3.5 or even 4A) and then run Phaser a second time. In this second run I would use the highest-resolution and let Phaser only refine the sites (located in the first run) during one cycle and calculate the combined phases. Thank you in advance for your suggestions and advice, Peter

2 1

Where to find optimized wxc_scale/wxu_scale weighting factors after optimization
by amadrona＠uci.edu 13 Aug '10

13 Aug '10

Hello, I ran a refinement optimizing geometry and B factor weighting factors using optimize_wxc=true optimize_wxu=true. I was given these statistics in the pdb header: Rwork Rfree Bonds Angles start .1588 .1838 .007 1.235 end .1454 .1780 .016 1.601 (1.37 A resolution) 1. I would like to find the optimized weighting factors in the log file but cannot. Instead I find the following (pasted below). However, the scale here doesn't make sense to me because many our greater than 0.5. How do I find the optimized values so that I can use them in further rounds of refinement? I'm sorry if this has been covered in previous posts but I could not find an answer. 2. Can anyone explain the concept of optimizing the B-factor? I don't understand how changing it brings you closer or further from an ideal model as oppose to xray. (which is how I make sense of refining the geometry) Thank you -Yarow ================================ xyz refinement =============================== Start r_work= 0.1462 r_free= 0.1784 bonds= 0.015 angles= 1.53 r_work= 0.1492 r_free= 0.1792 bonds= 0.005 angles= 1.08 scale= 1.00 r_work= 0.1484 r_free= 0.1788 bonds= 0.006 angles= 1.14 scale= 1.40 r_work= 0.1480 r_free= 0.1787 bonds= 0.007 angles= 1.19 scale= 1.80 r_work= 0.1476 r_free= 0.1785 bonds= 0.008 angles= 1.23 scale= 2.20 r_work= 0.1473 r_free= 0.1785 bonds= 0.008 angles= 1.26 scale= 2.60 r_work= 0.1471 r_free= 0.1784 bonds= 0.009 angles= 1.29 scale= 3.00 r_work= 0.1469 r_free= 0.1784 bonds= 0.010 angles= 1.32 scale= 3.40 r_work= 0.1467 r_free= 0.1783 bonds= 0.010 angles= 1.34 scale= 3.80 r_work= 0.1465 r_free= 0.1782 bonds= 0.011 angles= 1.36 scale= 4.20 r_work= 0.1464 r_free= 0.1782 bonds= 0.011 angles= 1.39 scale= 4.60 r_work= 0.1463 r_free= 0.1782 bonds= 0.011 angles= 1.40 scale= 5.00 r_work= 0.1461 r_free= 0.1781 bonds= 0.012 angles= 1.45 scale= 6.00 r_work= 0.1458 r_free= 0.1781 bonds= 0.013 angles= 1.49 scale= 7.00 r_work= 0.1456 r_free= 0.1781 bonds= 0.014 angles= 1.53 scale= 8.00 r_work= 0.1454 r_free= 0.1781 bonds= 0.015 angles= 1.57 scale= 9.00 r_work= 0.1453 r_free= 0.1780 bonds= 0.016 angles= 1.60 scale= 10.00 r_work= 0.1495 r_free= 0.1794 bonds= 0.005 angles= 1.05 scale= 0.85 r_work= 0.1501 r_free= 0.1797 bonds= 0.005 angles= 1.02 scale= 0.70 r_work= 0.1507 r_free= 0.1800 bonds= 0.004 angles= 0.98 scale= 0.55 Final r_work= 0.1453 r_free= 0.1780 bonds= 0.016 angles= 1.60

4 6

Restraints file for a new amino acid residue
by Joseph Noel 13 Aug '10

13 Aug '10

Hi All, How does one create a new CIF file using Elbow for a non-natural amino acid not found yet in the PDB? I know how to carry it out for the isolated residue readily (but of course thinks it is isolated and doesn't include the necessary peptide bonding) but how does one ensure the correct backbone restraints for it are included since it is not isolated but part of the chain? Joe ___________________________________________________________ Joseph P. Noel, Ph.D. Investigator, Howard Hughes Medical Institute Professor, The Jack H. Skirball Center for Chemical Biology and Proteomics The Salk Institute for Biological Studies 10010 North Torrey Pines Road La Jolla, CA 92037 USA Phone: (858) 453-4100 extension 1442 Cell: (858) 349-4700 Fax: (858) 597-0855 E-mail: noel(a)salk.edu Web Site (Salk): http://www.salk.edu/faculty/faculty_details.php?id=37 Web Site (HHMI): http://hhmi.org/research/investigators/noel.html ___________________________________________________________

3 2

too many outliers
by intekhab alam 13 Aug '10

13 Aug '10

Hi there I have recently solved a structure at 2.71A resolution using CCP4 (Refmac5) with R and R free of 22 and 29 respectively. The model is nicely fitted in the map and everything looks except in some loop region where the map is not fitted well. I just finished modelling and checked ramachandran plot which is showing unreasonably high number of outliers (12%) with only 65% in the favoured region. I am thinking to use phenix_refine with simulated annaeling and using the option fix bad chain rotamers. What else i can do aprt from this. i will be highly thankful for the suggestions. Apart from this can anyone let me know how -- INTEKHAB ALAM LABORATORY OF STRUCTURAL BIOINFORMATICS KOREA UNIVERSITY, SEOUL

2 1

wxu for anisotropic ADP refinement
by Joseph Noel 12 Aug '10

12 Aug '10

Dear Phenix User Community, If one would like to try different weights for anisotropic ADP refinement (ie fixing wxu) should one be focusing on numbers like - wxu = 199.878301 - instead of the usual low numbers such as - wxu = 0.25 - found during isotropic ADP refinement? While optimize X-ray/ADP weight is useful in phenix, I am still getting anistropic ADP values that are a bit outside what one might expect at 1.5 A compared to the PDB. For the latter, I check things using Parvati (http://skuld.bmsc.washington.edu/parvati/). Thanks! Joe ___________________________________________________________ Joseph P. Noel, Ph.D. Investigator, Howard Hughes Medical Institute Professor, The Jack H. Skirball Center for Chemical Biology and Proteomics The Salk Institute for Biological Studies 10010 North Torrey Pines Road La Jolla, CA 92037 USA Phone: (858) 453-4100 extension 1442 Cell: (858) 349-4700 Fax: (858) 597-0855 E-mail: noel(a)salk.edu Web Site (Salk): http://www.salk.edu/faculty/faculty_details.php?id=37 Web Site (HHMI): http://hhmi.org/research/investigators/noel.html ___________________________________________________________

2 1

difference in estimated error between phenix and refmac
by Ling Qin 12 Aug '10

12 Aug '10

Dear Colleagues, I am refining a 2.15 A structure that was previously refined with refmac by someone else. Without changing anything in the refmac-refined model and using all the default phenix.refine settings, I am getting pretty much the same R and Rfree (from 19.3%/21.7% to 18.9%/21.8%), with an ML estimated error of 0.22 A. In the refmac-refined pdb file, the estimated error is much lower: 0.16 (based on R), 0.144 (based on Rfree), and 0.096 (based on ML). I am using phenix.refine version 1.6_289, but also tried 1.5_2 with the same result. Is there an underlying reason for this difference? Thank you very much for your insightful opinions in advance. Cheers, Ling

3 2

autosol
by Abd Ghani Abd Aziz 12 Aug '10

12 Aug '10

Dear All, Just been trying to run autosol for SAD data with the new phenix (1.6.4-486) on ubuntu, but I get an error message: *********************************************************** Failed to carry out AutoSol_scale_and_analyze_mad: None of the solve versions worked ********************************************************************** xtriage appears to run OK, and I get the same error with unmerged or merged scalepack data. The same files in 1.6-289 (admittedly on OSX) work fine. I wonder if there is a known problem with this version of phenix? Thanks for any suggestions, Ghani

3 4

Disappearing density?
by Kyle Dolan 11 Aug '10

11 Aug '10

Hi all, I attempted to improve the density around a helix and short linker region using an average kick map but it didn't make things look much better. I then tried creating a composite iterative-build omit map from phenix.autobuild, but in this case the electron density around the helix/linker in question largely disappeared! Is there another approach I can use that might improve my maps, or should I start questioning my data? The dataset has >95% completeness to 2.7 A so I am very curious as to why I am missing the backbone now, where before I was only missing the side chain densities. One thing I am wondering is if the problem could have something to do with symmetry; the part of the map I am looking at may be close to a two-fold crystallographic symmetry axis and I have been told that these regions tend to be very noisy and hard to model--comments? Kyle Kyle T. Dolan Department of Biochemistry and Molecular Biology The University of Chicago ktd(a)uchicago.edu

4 6

Statistics for pdb deposition
by Elwood A. Mullins 11 Aug '10

11 Aug '10

I apologize if this has already been addressed. I'm trying to deposit a model to the pdb database, but there are a few required values in the Refinement Statistics section that I'm not sure where to find. 1,2) Cut-off sigma (F), Number unique reflections (observed) Looking at the log file, it appears that the cut-off is 0, which results in 330 reflections being rejected. The pdb header, however, lists the number of reflections at a value corresponding to 352 reflections being rejected. Why are these numbers different and which should I report? 3) R-factor (all) R-factor (all) includes both the working and test sets in addition to reflections rejected by the sigma cut-off. Does PHENIX calculate this value? I know R-factor (observed), which includes the working and test sets but not rejected reflections, is calculated. Thanks, Elwood

2 1

elbow: more detailed website : 404
by Lepore, Bryan 11 Aug '10

11 Aug '10

this link : http://www.phenix-online.org/elbow/docs/index_image.html is 404 the link is found on this page : http://www.phenix-online.org/documentation/elbow.htm ... IS there a "more detailed website"? i saw the reel site. -bryan

2 1