October 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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Fitting models into density - meaning of values
by Jessica Holien 30 Oct '13

30 Oct '13

I have been using Chimera to fit some homology models into the EM density (23A resolution) of a large complex. Although by eye it looks good I am trying to work out if statistically it is good. Can anyone tell me what is a good "Average Map Value" and what is a bad one? Thanks

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Coloring distance lines between atoms
by Tom Goddard 30 Oct '13

30 Oct '13

Hi Damien, Here is a Chimera Python script colordist.py that lets you color distance lines between atoms based on how long the distance is. The colors update as you move one model relative to another. After showing some distances, for instance with the "distance" command you would use command runscript colordist.py 8.5 green red to color the distance lines less than 8.5 Angstroms green, and longer ones red. The script needs to be in the directory you started Chimera in (e.g. on Linux), or you can specify a full path to the script "runscript /Users/Smith/colordist.py …", or use the Chimera "cd" command to change to the directory containing the script. You can select specific distance lines to color with the mouse and use runscript colordist.py 8.5 green red sel You can stop the color updating using runscript colordist.py or for just selected distance lines runscript colordist.py sel Tom On Oct 24, 2013, at 3:13 AM, Damien Larivière wrote: > Hi Tom, > > So, here is a reminder for the script we talked about. > > The idea is as follows: > > Once I have loaded several proteins in Chimera, once I have calculated distances between residue pairs that are displayed in the distance popup window, once I have displayed visually the distance as a colored stick pseudobond, then I would like a switch of the pseudobond color to occur when the distance is higher than a given value as I'm moving the proteins. > So, in my current manual modeling, I'm calculating a total of 24 distances between 5 proteins, I ask Chimera to display 24 pseudobond, most of them are initially let'say red, I load the script after having editing it with the distances and the associated maximal values, I move the proteins and the pseudobond color turn from red to yellow when the distance get lower than the maximal value defined for this distance in the script. And inversely, a pseudobond turns to red from yellow when it gets higher than a maximum distance. > > Let me know if you need more explanations. > > Many thanks for your help, > > Damien >

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color a small molecule in a .mol2 file by red to blue gradient of the partial charges
by Francois Berenger 30 Oct '13

30 Oct '13

Is it possible to do this in Chimera? I'd like a white background too. Thanks a lot, F.

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how to make the background of Chimera-generated images transparent
by Gea-Ny Tseng/FS/VCU 30 Oct '13

30 Oct '13

Dear Chimera developers and users: I would like to know how to make the background of Chimera-generated images transparent. I used to be able to do this with an older version of Chimera. But with Chimera 1.8, I could not figure out how to do this. There are options in the 'Color/Background' to adjust 'Opacity', which to me means that I could make the background transparent by using 'zero'. But this did not happen. Could you please advise? Thank you. Gea-Ny Tseng, PhD Dept of Physiology & Biophysics Virginia Commonwealth University

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Symmetry generation question
by Bala subramanian 29 Oct '13

29 Oct '13

Hello, 1) I have modelled one chain of a multimer. Since this is a modelled structure I dnt have any symmetry information in my pdb. In such case, how can I generate the symmetry related copies. Say I want to apply a fivefold symmetry along z-axis, how can I achieve it ? 2) I used a template structure from PDB to model my structure. What is the correct way to apply the symmetry of existing pdb model to my modeled chain. I tried this as follows, I opened my model as #0 and then the template pdb structure #1 and tried the following sym command and obtained an error as '#0 has no biological unit info.' sym #0 #1 Thanks, Bala -- C. Balasubramanian

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coloring plane by ESP
by Elaine Meng 29 Oct '13

29 Oct '13

Hi Marek, Just thought I'd mention that in Chimera you can color a plane that is in any orientation by the values in an ESP map. Unfortunately it doesn't work with the planes from Axes/Planes/Centroids, but you can create a rectangular plane with specified height and width with command "shape rectangle". Then you can open the molecule and the ESP map, activate/deactivate models (freeze/unfreeze them) and use the mouse to position the rectangle however you like in relationship to the molecule. Then you can use the "Surface Color" tool (aka Electrostatic Surface Coloring) to color the rectangle by the ESP map values. If you didn't already have an ESP map, you could use the PQR and APBS tools in Chimera to calculate one with APBS, or use the Coulombic Surface Coloring tool with option to "Compute grid" (i.e. make ESP map). Attached image is for 3eeb chain B, ESP map file 3eebB.phi ( available from link near bottom of the Surface Properties image tutorial <http://www.rbvi.ucsf.edu/chimera/docs/UsersGuide/tutorials/surfprop.html> ), and rectangle created with command: shape rectangle height 50 width 50 widthdiv 100 heightdiv 100 center protein It shows the area of strong positive potential near where the highly negatively charged ligand binds. Best, 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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no moleculr dispay with version 1.8
by Robert Wohlhueter 28 Oct '13

28 Oct '13

I have chimera-1.5.3 running on my Linux-AMD64 Ubuntu (12.10) computer. It works fine in every respect. Recently I installed version 1.8, with runs, but with one fatal flaw. By "runs", I mean the chimera screen comes up, the menus display. If I load (say, a pdb file), it seems to be there in the sense, for example, that I can open and view its sequence. BUT the molecule display window is absolutely blank (black). I suspect it has either to do with my python installation, or with my NVIDIA graphics driver. But whatever the problem, it effects only v. 1.8, not v. 1.5.3. For NVIDIA driver I'm using version 310.14. For python, I understand chimera uses 2.7. My python executable is indeed set as version 2.7.3 (that is, `python --version1 returns 2.7.3), though I have version 3 installed, and it could be used, if needed. I'm not all so clear on how envars PYTHONHOME and PYTHONPATH may or may not effect chimera. Of course, the easy way out is to stick with chimera-1.5.3 -- but one likes to stay up-to-date. Thanks in advance for any profound wisdom. Bob Wohlhueter

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Chimera-users October 2013