- phenixbb - phenix-online.org

AutoMR and capsids
by SIPPEL,KATHERINE H 23 Oct '09

23 Oct '09

Dear all, I am currently trying to use AutoMR to do molecular replacement on an icosahedral virus capsid. It is a T=1 capsid so there are 60 copies of the monomer per capsid and based on the Matthews coefficient there are ~3 capsids in the unit cell. The search model is 99% identical (thank God) but I am unsure how to approach this. Do I used the 60-mer as the model and search for three copies? Do I use a monomer for the model and search for 180 copies? Should I break the model down to smaller pieces (i.e. a 30-mer and copies=6, or 12-mer and copies=15)? I would appreciate any help I can get on this one. Thanks, Katherine -- SIPPEL,KATHERINE H Ph. D. candidate Department of Biochemistry and Molecular Biology College of Medicine University of Florida

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Partially occupied SO4 and waters
by Chris Waddling 21 Oct '09

21 Oct '09

I have a partially occupied sulfate ion that is refining to 55% along with one of two arginine side chains. Associated with the second conformation of the arginine, there is positive density for three partially occupied waters. In Shelxl, I can use the PART identifier to specify that the sulfate ion and the waters are not present simultaneously and are associated with their respective Arg side chain conformation. Is there a way to do this in Phenix? Thanks, Chris -- Dr. Christopher A. Waddling, Ph.D. University of California at San Francisco

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Re: [phenixbb] Molprobity percentile statistic
by hari jayaram 21 Oct '09

21 Oct '09

Thanks Nat and Pavel for your emails, Thanks for the suggestion of using phenix.polygon. The comparative analysis of my structure relative to others at my resolution was what I was after. And thats the reason I liked the molprobity statistics expressed as percentile since it helped me realize how far I have to go relative to other structures at the PDB. If its not too difficult can I cast my vote to report it inside the phenix GUI. Its just that running the full analysis inside of phenix is significantly faster than running it on the duke webservers. In molprobity If I remember correctly the overall score is some weighted average, and the molprobity paper also cautions against taking it too literally. Also If I remember the molprobity percentiles are absolute and not only composed of structures at similar resolutions . Regardless thanks for the hint about phenix.polygon . I just looked at my phenix.polygon report and I am afraid its a little asymmetric. Hari On Mon, Oct 19, 2009 at 9:58 PM, hari jayaram <harijay(a)gmail.com> wrote: > Thanks Nat and Pavel for your emails, > Thanks for the suggestion of using phenix.polygon. The comparative > analysis of my structure relative to others at my resolution was what > I was after. > > And thats the reason I liked the molprobity statistics expressed as > percentile since it helped me realize how far I have to go relative to > other structures at the PDB. If its not too difficult can I cast my > vote to report it inside the phenix GUI. Its just that running the > full analysis inside of phenix is significantly faster than running it > on the duke webservers. > > In molprobity If I remember correctly the overall score is some > weighted average, and the molprobity paper also cautions against > taking it too literally. Also If I remember the molprobity percentiles > are absolute and not only composed of structures at similar > resolutions . > > Regardless thanks for the hint about phenix.polygon . > I am attaching a snapshot of my polygon ..I an afraid its a little > asymmetric. > > Hari > > On Mon, Oct 19, 2009 at 7:48 PM, Pavel Afonine <PAfonine(a)lbl.gov> wrote: >> Hi Hari, >> >> if you run phenix.model_vs_data you will get those numbers (namely: >> Ramachandran outliers, clashscores, CB-deviations; although you will not >> get "Molprobity score" simply because I don't know what it is and so I >> didn't add it): >> >> phenix.model_vs_data model.pdb data.mtz >> >> Nat: every time time you run model_vs_data for whatever purpose (getting >> fmodel, etc...) you get an object that contains all these numbers. >> >> Pavel. >> >> >> On 10/19/09 3:32 PM, hari jayaram wrote: >>> Hi i just started using the phenix GUI front-end to Molprobity . Its >>> really nice the way it plugs into coot and displays all the statistics >>> etc. >>> Is there any place that it also reports the percentile clashscore and >>> percentile Molprobity score for overall model quality a la the >>> webserver at molprobity.biochem.duke.edu >>> >>> Thanks >>> Hari >>> _______________________________________________ >>> 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 >> >

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Molprobity percentile statistic
by hari jayaram 20 Oct '09

20 Oct '09

Hi i just started using the phenix GUI front-end to Molprobity . Its really nice the way it plugs into coot and displays all the statistics etc. Is there any place that it also reports the percentile clashscore and percentile Molprobity score for overall model quality a la the webserver at molprobity.biochem.duke.edu Thanks Hari

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Re: [phenixbb] pseudo-merohedral twinning or pseudo-symmetry?
by Gino Cingolani 17 Oct '09

17 Oct '09

Laurie, I had a similar problem. Scaling statistics in P212121 were OK, and - of course - no twinning was detected ... but nothing made sense during refinement. Looking at the data more carefully I found that if one rescales in P21, the b-angle was stably refined to 90.20 with ~30% better Rsym than in orthorhombic. When running xtriage on the P21 data, I found the data were indeed "pseudomerohedrally-twinned" with twinning fraction ~0.38. Good luck! Gino

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pseudo-merohedral twinning or pseudo-symmetry?
by Laurie Betts 17 Oct '09

17 Oct '09

Hi - We have a data set that seems to process well in primitive orthorhombic. a=80, b=87, c=114. The data has overall Rsymm around 10% to 2.6 Angstrom, where I/sigI > 2, and Chi-squared is around 1.4. Phenix.xtriage shows some pathology in intensity statistics such that the L-test indicates <|L|> = 0.414 and <L^2> = 0.241, with the L-test Z score = 7.334. The Wilson ratio for acentric refls is 1.774. According the xtriage, There were no "pseudomerohedral" twin laws found, and the comments at the end say "As there are no twin laws possible given the crystal symmetry, there could be a number of reasons......" Is it more likely that this is a case of pseudo-symmetry, or would one not expect the intensity statistics to have the values they do in that case. Also, is the absence of twin laws defined by the fact that proper merohedral twinning is not possible for P222 space groups? Still confused, Laurie Betts

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autobuild
by Colin Levy 16 Oct '09

16 Oct '09

Hi, can autobuild be setup to use kicked maps when starting from a molecular replacement model? Thanks Colin

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Re: [phenixbb] grouped occupancy definitions
by Dr. Mark Mayer 16 Oct '09

16 Oct '09

Hi Pavel, I'm digging in docs and list serv but could not find out, and figured you probably know faster. I need to make an occ.params file for some groups of non adjacent side chains which interact with each other, and associated waters. 1) How do I select ACs 2) How do I constrain water occupancies so that their Q + that of coupled protein atomes does not exceed 1. If I match the AC flags for the waters and side chains will this take care of it. e.g. if residues 2 and 21 have coupled ACs and waters 101 and 102 move in when residue 21 is in one of its ACs how would I define below? refinement { refine { occupancies { constrained_group { selection = chain A and resseq 2 selection = chain A and resseq 21 selection = chain W and resseq 101 selection = chain W and resseq 102 } } Thanks !!! -- +++++++++++++++++++++++++++++++++++++++++++++++++++++++ Mark Mayer Ph.D.

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low resolution refinement question
by Peter Grey 16 Oct '09

16 Oct '09

Dear Phenix users, I refine a large complex with three monomers in ASU at very low resolution - 4.5A - and would like to ask two questions. - Could you give some tips about refinement at this resolution other than rigid body refinement - Can TLS and grouped B-factors work at this poor resolution ? - I would really prefer that rigid body refinement will strictly obey the NCS that was found in the molecular replacement solution. I understand constrained NCS does not exist yet in phenix but is there something approximate that can be used in rigid body refinement ? I tried the conventional restrained NCS and the result was just like without restrains. Thank you for your time , Peter.

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Why is CIF monomer data split into individual files?
by Joe Krahn 14 Oct '09

14 Oct '09

Is there a good reason not to merger all monomer data into a single file, similar to PDB's components.cif? My first thought is that it is a performance issue. However, I wrote a simple CIF parser in Tcl, and found that carefully designed regexp processing can index data segments very fast. The entire components.cif takes just a few seconds. (The key is to use a regexp that matches an entire data block, and not tokenize the whole file.) So, I am thinking that a single merged file might be better. With separate files, there is already a need for a list of residues (mon_lib_list.cif) which could just as well be file offsets. So, even if parsing is not so fast, it is not an issue because we already have an index file. One problem with separate files is that it relies on the 3-letter residue name to be unique. With a merged file, a different database key can be used without concern for filename restrictions. The PDB format was originally designed so that HET 3-letter codes only need a file scope, where HETNAM defines the full name of each HET residue in a file. Everyone has been using HET codes the same as standard residues, which has cause the 3-letter codes to become meaningless database keys rather than useful abbreviations. Eventually, we will run out of 3-letter codes, and will have to change. Why not start sooner rather than later? Even now, there are potential conflicts. For example, CCP4 has DNA residues using a lower-case d, which may not provide a unique filename for non-POSIX case-insensitive operating systems. If anyone actually wants a Tcl CIF parser, I can share it. I only wrote it as a simple and efficient way to read CIF files from a CCP4i script. Joe Krahn

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