December 2013 - Chimera-users - RBVI Mailing Lists

Constrainted fitting
by Christoph Wigge 22 Mar '19

22 Mar '19

Dear all, I would like to fit two protein monomers that form a dimer into an em density map. I know from previous mutagenesis studies that the binding takes place with two tryptophan residues and the counterpart binding pocket. How can I set this interaction as fixed so that chimera fits the rest of the molecule according to the density map without continuously changing this part of the essential protein protein interaction? I would like to fit that interaction manually and then exclude it from the automatic procedure. Thank you very much in advance. Bests Christoph Wigge

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volume planes tool
by Jeff Triffo 22 Jun '16

22 Jun '16

hi folks, anyone know if the volume plane tool will support arbitrary orientation of the plane any time soon? -Jeff

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Re: [Chimera-users] Display a spider volume data in a specific orientation
by Elaine Meng 08 May '14

08 May '14

Hi Zongli, This is not my area of expertise (our expert is currently out of town) -- at first I thought you could use "Transform Molecule Coordinates" (under Tools... Movement), but now I see that it works only on atomic structures rather than maps: <http://www.cgl.ucsf.edu/chimera/docs/ContributedSoftware/transform/transfor… > It only works on molecular structures because it actually changes the atomic coordinates, without changing the model transformation. I've figured out one workaround, but it is both crazy and slightly tedious: (1) open your map (say as model 0). (2) open any atomic-resolution structure, it doesn't matter what, and open it twice -- now you have three models. Don't move them separately from the map (yet). Let's say the atomic structures are models 1 and 2. (3) use "Transform Molecule Coordinates" with desired Euler angles and shift on one copy of the atomic structure (say model 1). (4) use the match command to superimpose the other copy of the atomic structure on the one that was transformed: match #2 #1 (the command can use the whole models since they should have exactly the same atoms) (5) use the matrixcopy command to apply the transformation matrix of the second copy of the atomic structure to the map: matrixcopy 2 0 You might think "why do I need two copies of the atomic structure? can't I just transform one copy and then use matrixcopy?" ... in fact that's what I tried first, but after it didn't work, I realized it was because the Transform tool works by changing the coordinate values and not the stored matrix of the model. It is necessary to match the second copy to generate a corresponding matrix, and then matrixcopy can be used. I'm CC-ing the chimera-users(a)cgl.ucsf.edu list in case other Chimera users have suggestions. Our expert Tom G should be back next week and he might also have ideas. In general, it's better to send Chimera questions to that mailing list instead of just me, because I could be away from work or (like now) lacking a good answer! I hope this helps, Elaine ----- Elaine C. Meng, Ph.D. UCSF Computer Graphics Lab (Chimera team) and Babbitt Lab Department of Pharmaceutical Chemistry University of California, San Francisco On Apr 7, 2010, at 11:51 AM, Li, Zongli wrote: > Hi Elaine, > I have a spider volume data (or mrc density map) from which I got a > serious 2D projections. I have the Euler angles for each projection. > Is there a way in Chimera that I can use those Euler angles to > display the 3D spider volume data (or mrc density map) in a specific > orientation that corresponding to that 2D projection? > Thank you very much in advance. > Best, > Zongli > > **************************************** > Zongli Li, Ph.D. > > Howard Hughes Medical Institute > Department of Cell Biology > Harvard Medical School > C Building, Room 420B > 240 Longwood Avenue > Boston, MA 02115 > > Tel: 617-432-4095 (Office) > 617-432-4708 (EM Suite) > 617-432-4091 (Computer room) > Fax: 617-432-1144 > Email: zongli_li(a)hms.harvard.edu > *************************************** >

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Set and rna commands
by pythonchemia Gazeta.pl 30 Dec '13

30 Dec '13

Hello ! I have winXP and Chimera version 1.8. I wanted to use the commands rna and set. Unfortunately, they do not work. Why? What is it? I tried to repeat the example of the User's Guide for rna command and failed. Please help me or give me examples on the set command and rna Sincerely, Janusz Grabowski

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Find pseudo 2-fold axes relating heavy and light chain
by Jian Guan 30 Dec '13

30 Dec '13

Dear all, I am trying to find pseudo 2-fold axes relating heavy and light chains in the constant domain and variable domain respectively in Fab. I tried Define Axes, it failed. And I made artificial double heavy chain, it failed again. I can only get axis which is horizontal passing through both light chain and heavy chain. It is not what I want. Can anyone help to give some clues? Thanks Jian

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Failure of energy miminization
by Ross KK Leung 30 Dec '13

30 Dec '13

In August there was a discussion entitled "Minimization and mystery nonstandard HIS atom name" and that's the exact problem supposed to have been solved last year. What I did is similar to Jason (http://www.cgl.ucsf.edu/pipermail/chimera-users/2013-August/009069.html), and unfortunately I'm unable to resolve the problem, giving that I'm using chimera 1.8.1 on a Win 7 32G RAM computer. I attach two files, one succeeded till completion while the other one failed early. What I did is simply "Structure editing", next, ok, next, .. Charges of 0.0 were assigned to the unknown atoms 1 model(s) had non-integral total charge Details in reply log No MMTK name for atom "HC1" in standard residue "ALA" Any suggestions to fix the problem is highly appreciated because Chimera is so impressive and I've been using it for many good analyses already. A pity to give up and switch to other programs at this very last stage.

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Reset surface programatically from python
by Thomas Hrabe 30 Dec '13

30 Dec '13

Hi everyone, I have this line of code where I want to load a density and export a negative surface of it: import chimera as ch mod = ch.openModels.open(‘./density.em')[0] mod.surface_levels = [-1,0] mod.display = True ch.exports.doExportCommand('WebGL', 'tmp.html’) However, the surface of the density is rendered for positive values. How can I refresh the display after I specify the surface_levels? Thanks, Thomas

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Re: [Chimera-users] [chimera-dev] writing in b-factor field
by Elaine Meng 30 Dec '13

30 Dec '13

On Dec 29, 2013, at 8:43 AM, MARIA VITTORIA CUBELLIS <cubellis(a)unina.it> wrote: > Dear sir/madam, > I have a file that associates to each amino acid of a protein A a given value v. > I would like to transfer this value to the b-factor field of the protein A the value v. I have a single value for each aminoacid N1,N2... I would like to transfer the value to each atom > > let say > > N1 C v1 > N1 CO v1 > N1 N v1 > .... > .... > N2 C v2 > N2 CO v2 > N2 N v2 > > and so on > > is it possible to this withe chimera? > thank you > > mvcubellis Dear M V Cubellis, Yes, you can do it, but another question is why do you want to do it? I'm guessing you want to color by those values. In Chimera you can assign the values to the atoms or residues directly as "attributes" and then do coloring to show those values. The B-factor from an input file is one atom attribute named bfactor, but you can create additional attributes with whatever names you wish, and color by any of them. The main work for you is to create an "attribute assignment file" which is mostly tab-separated columns with the atom (or residue) specifiers and values. The necessary format is described here, and there are also some example files: <http://www.rbvi.ucsf.edu/chimera/docs/ContributedSoftware/defineattrib/defi…> Probably the trickiest part is how to specify the residues in the file, e.g. could be something like :12.a for residue 12 in chain A. See instructions on atom/residue specification: <http://www.rbvi.ucsf.edu/chimera/docs/UsersGuide/midas/atom_spec.html#basic> Once you have created that text file, you can read it in with Define Attribute (in menu under Tools… Structure Analysis) or command defattr. <http://www.rbvi.ucsf.edu/chimera/docs/ContributedSoftware/defineattrib/defi…> <http://www.rbvi.ucsf.edu/chimera/docs/UsersGuide/midas/defattr.html> Then Render by Attribute (which may automatically appear when you create the attribute, but also is in menu under Tools… Structure Analysis) can be used to show the values with colors and/or radii: <http://www.rbvi.ucsf.edu/chimera/docs/ContributedSoftware/render/render.htm…> If you really wanted to write a PDB file with values in the B-factor column, you would still need to create an attribute assignment file as described above, but more specifically to assign an atom attribute named bfactor. Then when you use the File menu or write command to output a PDB file, your values will be in the B-factor column. See also the Attributes tutorial for examples of coloring by attribute value. <http://www.rbvi.ucsf.edu/chimera/docs/UsersGuide/tutorials/attributes.html> I hope this helps, Elaine ---------- Elaine C. Meng, Ph.D. UCSF Computer Graphics Lab (Chimera team) and Babbitt Lab Department of Pharmaceutical Chemistry University of California, San Francisco

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keyboard shortcuts
by Dougherty, Matthew T 30 Dec '13

30 Dec '13

I am writing a bunch of USB-HID keyboard shortcuts for some extensions I am writing. Usually one shortcut per def. Since my decoding of HID is integrally tied to the extension, I would like to simplify all my shortcuts coming from one device to one def. As of now if I have 100 button commands I have to 1) register 100 shortcuts, 2) create 100 defs, 3) do corresponding stuff in my extension. I would prefer to call one def that passes the actual keyboard string to my extension, thereby simplifying my user accelerators to just registration. How do I get the string within my keyboard shortcuts python file? thanks, Matthew Dougherty National Center for Macromolecular Imaging Baylor College of Medicine

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display of improper peptide bond
by Tatiana Domitrovic 30 Dec '13

30 Dec '13

Hi, I am trying to get rid of an improper bond that chimera is displaying between two nearby segments that are actually cleaved. The bond is distorted, creating long CACB bonds if B-spline mode is active. I tried to turn off the auto-chaining, but didn’t work. Because PYmol can properly display these segments as independent polypetides, I was wondering if there is other adjustment that I can try before manually deleting the bond. The PDB is 1ohf and the bond is between residue 570 and 571. Cheers,

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Chimera-users December 2013