- Chimera-users - RBVI Mailing Lists

Opening compressed trajectories
by Francesco Pietra 02 Jan '08

02 Jan '08

I found comfortable to deal with mdcrd compressed (gz) files directly in Amber's ptraj. This saves much disk space. I wonder whether this could be made available for Chimera. The scope would be twofold: other that saving disk space, shorted times of ssh transfer from the computing machine to the desktop with Chimera. Happy 2008! francesco pietra ____________________________________________________________________________________ Be a better friend, newshound, and know-it-all with Yahoo! Mobile. Try it now. http://mobile.yahoo.com/;_ylt=Ahu06i62sR8HDtDypao8Wcj9tAcJ

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saving complex structure
by bala 02 Jan '08

02 Jan '08

Dear chimera friends, I have a protein-RNA complex pdb structure. I want to remove the RNA in the crystal structure and put my RNA molecule in to the binding site. Since my RNA is very big around 20bp long, i prefer to manually dock my RNA followed by a big simulation than a automated docking. I tried in chimera and i saved the complex structure with the option "save the displayed atoms". But when i see the pdb structure, it has the coordinates of RNA molecule but not the protein. Also when i open the pdb in chimera, it shows me the protein structure. Kindly write me your comments on using chimera i) for such a manual docking and also ii) how to save the complex structure. Wish you all a happy new year, Bala

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Command for volume and area calculation
by shengzhiya＠nibs.ac.cn 27 Dec '07

27 Dec '07

Dear all, May I know if there is some command in chimera for measuring volume and area like in the menus: “Tools…Surface/Binding Analysis…Measure Volume and Area”? Thanks in advance! Happy new year and have a nice holiday! Zhiya

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formal charge or net charge
by snoze pa 25 Dec '07

25 Dec '07

Dear Chimera Users, Is it possible to calculate the net charge or formal charge of unknown residues using chimera. I have a large set of molecules for which i am trying to calculate the net charge on each molecule. Thanks in advance s

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rmsd cluster analysis
by Elaine Meng 24 Dec '07

24 Dec '07

Hi Francesco and others, People with MD trajectories can also use this new EnsembleCluster tool (available in the most recent daily builds) by: - viewing the whole trajectory with the "MD Movie" tool, or at least all the frames you want to cluster - from the MD Movie dialog menu, choosing File... Save PDB and saving "all frames" to a file - quitting from MD Movie and opening the new file with File... Open - choosing Tools... MD/Ensemble Analysis... EnsembleCluster, clicking the line that shows that new file, then OK I just tried this to make sure it works. The clustering calculation may take a while, but eventually another dialog with results should appear. This tool is still under development and may change, but this will at least allow users to try it on trajectory ensembles as well as NMR ensembles. Best, Elaine ----- Elaine C. Meng, Ph.D. meng(a)cgl.ucsf.edu UCSF Computer Graphics Lab and Babbitt Lab Department of Pharmaceutical Chemistry University of California, San Francisco http://www.cgl.ucsf.edu/home/meng/index.html

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Transparent background
by Abbas 20 Dec '07

20 Dec '07

Hi, One feature I really appreciated about chimera was the ability to make pictures without a background, however recently i realized this is not possible anymore I checked out under the effects dialog under tools>viewing controls and it give me an error saying this wasn't supported. I haven't changed my computer since i first started using chimera I have updated to the latest version of chimera available for OSX 10.4, I wonder if this is the cause of the problem. I would really like to have pictures without backgrounds like I used to, I know PyMol lets you do it, but I dislike this program. In any case I would greatly appreciate any help/pointers on this issue. Thanks in advance. abbas.

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Re: [Chimera-users] fitting models into maps
by Tom Goddard 20 Dec '07

20 Dec '07

Hi Dan, The Chimera fit model in map tool doesn't give a correlation value. To get a correlation requires you have two maps to compare, so first a map needs to be calculated from the PDB model that matches the resolution of the experimental map. Although I'd like to have that in Chimera, it is not currently there. I have used the EMAN pdb2mrc program to compute the map. Then you can use the Chimera fit map in map tool to get a correlation value, or you could use fit model in map, then open the map calculated for the PDB and find the correlation for the orientation obtained for the PDB model. You're right that reported correlation values depend on some often unreported parameters. First there is the method used for producing a map from the PDB model. Then the correlation depends on the part of the volume used. I would guess this is typically the portion within a certain contour level of the PDB map. What contour level? Something like 1 standard deviation is not sensible since it depends on the size of the map (the extent of padding). Probably a contour level that encloses a given volume -- maybe the volume enclosed by the solvent excluded surface of the PDB model with a reasonable probe radius. Would be nice if Chimera automated this calculation starting from the fit model in map position -- some day, hopefully in 2008. Reporting average density value at the atom positions would only make sense if the map is normalized. Maybe reporting that value in standard deviations. But the standard deviation depends on how much empty volume surrounds the structure, so that is not very satisfactory. Chimera reports that number so you can compare different fits in the same map -- only relative values are meaningful. Another value I have seen reported is the number of atoms outside a certain contour level of the experimental map. The fit model in map tool reports that in the reply log (Favorites / Reply Log). Of course it depends on how you set the contour level. Again if you set that as some number of standard deviations that depends on the map size. Alternatively you could set the contour level so the experimental map encloses the expected volume. Menu entry Tools / Volume Data / Measure Volume and Area can help set such a contour level. Seems correlation is the most meaningful number. You can calculate the standard deviation of a map from its mean in newer versions of Chimera with menu entry Tools / Volume Data / Volume Mean, SD, RMS. Tom Daniel Southworth wrote: > Tom: > > Hi. I'm a post-doc in David Agard's lab and I have a question about > the "fit model in map" function in chimera. I'm having some good > success fitting crystal structures into my low-resolution em maps > using this function once I get a global fit either by hand or using > situs. I'm wondering if there is any way to get a correlation value > out of the fits or how people typically report on their confidence of > the chimera fitting in publications? I know correlation values are > often different from program to program so perhaps the best measure is > to state the average map value? Any help would be great - thanks. > > Dan

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superimpose --matchmaker.
by Vinay Kumar 19 Dec '07

19 Dec '07

Hi all, There have been a few posts previously regarding superimposing of molecules. using matchmaker would work for a pdb file. I was curious if small molecules (ligands) could be matched. I did check out the documentation and the command match. But what i am not sure abt is, in wht format should the input file for a small molecule be?? could someone suggest!! regards, Vinay

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Question regarding multiple mutant in the same chimera session
by Jean-Didier Maréchal 18 Dec '07

18 Dec '07

Hi, Is there a way to copy, in the same instance of chimera, a model X time? I'd like to generate different mutant of the same prot and have them stocked in the same session of chimera. Cheers, JD -- Dr. Jean-Didier Maréchal Assistant Professor Computational Bioorganic and Bioinorganic Chemistry @Transmet Unitat de Química Física Departament de Química Universitat Autònoma de Barcelona 08193 Bellaterra, Spain Tel: +34.(0)1935814936 Fax: +34.(0)1935812920 e-mail:jeandidier.marechal@uab.es

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rmsd cluster analysis
by Francesco Pietra 18 Dec '07

18 Dec '07

Is it feasible to command a cluster analysis from rmsd? I would like to group for likeliness snapshots from MD with respect to, say, the structure from which MD was started. Thanks francesco pietra ____________________________________________________________________________________ Be a better friend, newshound, and know-it-all with Yahoo! Mobile. Try it now. http://mobile.yahoo.com/;_ylt=Ahu06i62sR8HDtDypao8Wcj9tAcJ

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