April 2012 - Chimera-users - RBVI Mailing Lists

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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font size in pull-down menus
by Boaz Shaanan 09 Oct '13

09 Oct '13

Hi, Is there a way to change the font size of the pull-down menus? For some reason on the Windows (XP) v.1.5.1 they seem smaller to me. Nothing in terms of graphics (or my eyesight) has changed since I upgraded to 1.5.1 recently. Thanks, Boaz Thanks, Boaz Boaz Shaanan, Ph.D. Dept. of Life Sciences Ben-Gurion University of the Negev Beer-Sheva 84105 Israel Phone: 972-8-647-2220 ; Fax: 646-1710 Skype: boaz.shaanan‎

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How to place a metal ion in protein model
by Suneel N.A. 18 May '12

18 May '12

Hi Its my pleasure to introduce myself, I am Suneel, graduate student from India. I am not a bioinformatician by profession but a eager aspirant of learning bioinformatics. I am new to Chimera, but as I started using it, the desire for leraning Bioinformatics increased more and more. Chimera is such an awesome tool packed with so many options. I love it . I have small question for you. I have a predicted the structure of protein using in silico tools (based on homology modeling). Literature sates that this protein binds to Magnesium. Now I would like to know if I can use chimera to place the metal in the modeled structure and prove/validate it based on metal geometry. Please do the needful. Thanking you in anticipation yours sincerely suneel -- *Suneel Narayanavari. A* Graduate Student Prof. Manjula Sritharan's Laboratory of Infection Biology Department of Animal Sciences School of Life Sciences University of Hyderabad Hyderabad-46

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Amber Force Field
by Forbes J. Burkowski 04 May '12

04 May '12

Hi: I have noticed that scripts can start with: import MMTK import MMTK.ForceFields from MMTK.ForceFields import Amber94ForceField We are doing some side chain packing studies that would benefit from the availablity of "easy" force field calculations. Currently, the algorithm works with useRotamers() to set two neighbouring rotamers and this is followed by a simple energy calculation to evaluate the interaction energy between the two rotamers. Right now, the energy calculation is only a bit more sophisticated than a steric collision detector. Question: Can we use some functions in the MMTK.ForceFields module to get an improved energy calculation? Any suggestions would be appreciated. Cheers, Forbes

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Re: [Chimera-users] transform coordinates of multiple volumes
by Elaine Meng 03 May '12

03 May '12

On Apr 27, 2012, at 9:26 AM, Ludovic Renault wrote: > Hi Elaine, > I have 120 or so 3d volumes (EM maps). They are all equivalent and are centered at the same position. > I would like to move each one of these 120 volumes by a specific value in terms of euler angles and shift (in pixels I assume). I can use the 'trAnsform coordinates' tool but then if I save the map, it is not saved with the new coordinates. > So > 1- How to (Or can I) save the new coordinates for each volume? > 2- Can I use command lines to automate the process for example by giving the command a text file with the specific coordinates for each volume? > > I did do the rotation with spider software, but the shifting doesn't work because the volume(s) go outside of the box. So if all the above is not doable, is it possible to increase the volumes boxe size in chimera, then I could use the shift function in spider? > > I hope I'm clear enough. > Thanks, > Ludovic Hi Ludovic, It is recommended to send Chimera questions to the chimera-users list (CC'd) -- I'm not the top expert on volumes, so others may have better answers! I think the shift in Transform Coordinates is not in pixels but in units of length. <http://www.cgl.ucsf.edu/chimera/docs/ContributedSoftware/transform/transfor…> How the volume grid units map to units of length can be viewed by using Features...Coordinates in the Volume Viewer menu. Chimera has commands for translation (move) and rotation (turn) in X,Y,Z coordinate systems, but I don't know of a command to apply Euler rotations. <http://www.cgl.ucsf.edu/chimera/docs/UsersGuide/midas/move.html> <http://www.cgl.ucsf.edu/chimera/docs/UsersGuide/midas/turn.html> About saving a transformed map: The map formats don't include transformation information, so there is no way to save EXACTLY the same data, except transformed. However, you can resample the map onto a new grid, and then save the new map. The values at the new grid points are determined by interpolation, so there will be some (generally minor) data loss. <http://www.cgl.ucsf.edu/chimera/docs/UsersGuide/savemodel.html#afterfitting> The resampling of one map onto the grid of another can be done with command "vop resample", for example: vop #1 resample onGrid #0 <http://www.cgl.ucsf.edu/chimera/docs/UsersGuide/midas/vop.html#resample> To save the new resampled volume to a file, you could use "File... Save Map as" in the Volume Viewer dialog or the command "volume" with its "save" option. However, I see that "vop resample" is most pertinent for saving a map that has been fitted to another. In your case you are simply transforming the map, so it is unclear on what grid you could resample. Maybe there is some way to make a "dummy" grid in the right place. Although "vop cover" extends a map, it assumes periodicity of that map, whereas I assume you want zeroes in the expanded parts. Perhaps expanding a map with zeroes could be done using "vop add" to add a dummy zero map to your data set of interest. Sorry I couldn't give a more complete solution, 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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Just want atom distances
by Patricia LiWang 30 Apr '12

30 Apr '12

Hello users group, I don't want anything complicated-- I just want to get some rough distances between atoms. So I go to Tools Structure Analysis Distances A window comes up with an empty table. (No instructions on how to pick atoms) A search of the Chimera documentation tells me I have to Control-leftclick to pick two atoms But no matter how often I click and click and click, it never gives me anything. I can't get even one atom to show up in the panel, let alone two. The side chains are sitting right there, getting clicked away, with nothing happening in the table. I am reading so many similar documentation pages, and apparently there is a difference between "selecting" and "picking" So I figure I'll just use the command line. But the instructions don't even bother to tell you how to use the command line to get the distance between two atoms. There is documentation on how to get distances between something and a "plane". Why do they make this so hard? Surely this is the main "simple" thing people want to do with this program. Would someone please tell me how to Pick or Select or Whatever two amino acids (any atom in them would be fine) and get a distance? Or better yet, please tell me the exact command line command I can use to get the distance between Asparate 234 carboxyl oxygen and Aspartate 295 carboxyl oxygen, both from chain "G"? Thanks! Patti ---------------------------------------------------------------------------

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Measure contact between copies of the same map
by Giovanni Cardone 30 Apr '12

30 Apr '12

Hi, I can use the tool measure contactArea on the surface models of two different maps, but I can not make it work when using it on two copies of the same map: no matter how much I move one map with respect to the other, the first surface listed in the command line will always be entirely colored in red (using offset 0). It looks like the command ignores the transformation. Is this the expected behavior? I can work around it by resampling the maps after the transformation (vop resample # onGrid #), but I liked more the idea of doing the measure without this additional step. Tested it with the latest alpha version 1.7 (build 36320). Thank you, Giovanni

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Contour mapping
by Nikolay Igorovich Rodionov 30 Apr '12

30 Apr '12

Hi all, I was wondering if anyone could help me create an accurate contour map based on surface charge. I've tried rendering my molecule by charge, then using the surface clipping, capping, and the color zone tools. However, the coloring varies based on how I orient the plane. Does anyone know a better and more accurate way to creating a contour map? Nikolay Rodionov

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gaussian filter
by Mike Strauss 30 Apr '12

30 Apr '12

Hi, I've been using the gaussian filter for a number of years to help me display my noisy data. I'd like to understand what it's doing a bit better, and so I need help with the following code: ijk_linewidths = map(lambda step: linewidth / step, g.step) what is the resulting length of ijk_linewidths? I can't seem to figure out what type of data type g.step is. Is it a feature of the image itself, or where does it come from? Best Regards, mike

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