March 2008 - Chimera-users - RBVI Mailing Lists

[chimera-users]torsional angle
by 吴超 11 Mar '08

11 Mar '08

Hi, folks! I have a problem about the measurement of torsional angle. In the chimera users' guide about the command angle, as follows, it says that if I select the atoms simultaneously, the order information will get lost. How can I keep the order information since I need it to calculate the angle I want exactly? For example, in the following command I originally want to calculate the n-ca-c-n(182) dihedral, angle :181.a@n,ca,c:182.a@n but in fact what chimera gave me was may be c-ca-n-n(182). I want to calculate a lot of diheral information so I can not click one by one in the gui mode, I wonder is there any way that I can get what I want . Thanks! Usage: *angle* *atom1 atom2 atom3* [ *atom4* ] *Angle* reports the bond angle for three specified<http://www.cgl.ucsf.edu/chimera/1.2199/docs/UsersGuide/midas/atom_spec.html…>atoms or the dihedral angle for four specified<http://www.cgl.ucsf.edu/chimera/1.2199/docs/UsersGuide/midas/atom_spec.html…>atoms. The order of specification is important, but atoms need not be connected. The angle value in degrees is reported in the status line<http://www.cgl.ucsf.edu/chimera/1.2199/docs/UsersGuide/chimerawindow.html#s…>and *Reply Log*<http://www.cgl.ucsf.edu/chimera/1.2199/docs/UsersGuide/reply.html>. The atoms can be specified collectively using the word *selected*, *sel*, or *picked* if the current selection<http://www.cgl.ucsf.edu/chimera/1.2199/docs/UsersGuide/selection.html>contains only the three or four atoms of interest; the order in which the atoms were selected<http://www.cgl.ucsf.edu/chimera/1.2199/docs/UsersGuide/selection.html>(most likely picked<http://www.cgl.ucsf.edu/chimera/1.2199/docs/UsersGuide/selection.html#picks…>) is used. When order information is lacking (for example, the atoms were selected simultaneously), the angle actually measured may not be the one intended. There are no automatic updates if the angle changes. A new command must be issued to measure the changed angle. -- Chao Wu Currently: National Institute of Biological Sciences, Beijing Huang Niu's Lab http://www.nibs.ac.cn/ Tel: 80726688-8572 Address: Beijing ZhongGuanCun Life Science Park, NO.7 Science Park East Road, NIBS B427 Postcode: 102206 Life Science Honors Program, China Agricultural University PO.1055, NO.2 YuanMingYuan west road, Beingjing, 100094 P.R. China Tel: 86-10-62812484 E-mail: lynnwuchao(a)gmail.com

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pdb format and charges
by Terry Lang 06 Mar '08

06 Mar '08

Hey Everyone, I would like to use Chimera to write charges for a pdb file in the b-factor column. I feel like this is possible but couldn't quite figure out how to do it. Sincerely, Terry -- P. Therese Lang Post Doc Alber Lab, UC Berkeley

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one question about slicing
by Martin 06 Mar '08

06 Mar '08

Hi, I write in this mail to ask your great help on the slicing of MRC files. I want to slice a map in MRC format in half and save it as a new MRC file which only contains the remaining half map. However, it seems that the "Per-Model Clipping" function of Chimera can only work on the visualization mode, without connection to the "Save map as" function to attain a new map file. I am wodering if there is any other method to realize my intention. Thank you very much! Sincerely yours, Jian

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Unit cell coordinates, Python / Chimera
by Tom Goddard 05 Mar '08

05 Mar '08

Hi Rachel, Attached is Python code that prints the unit cell axes of open PDB models to the reply log. You open the PDB models, then open this script, and the results appear in the reply log (menu Favorites / Reply Log), for example: 1a0m.pdb unit cell axes a axis = 44.400 0.000 0.000 b axis = 0.000 44.400 0.000 c axis = 0.000 0.000 23.500 I figured out the needed Chimera calls by looking at the Chimera Python code for the Unit Cell tool located in your Chimera distribution in chimera/share/UnitCell/__init__.py and I homed in on the show_outline_cb() function to quickly figure out the attached code. On the Mac this code is in Chimera.app/Contents/Resources/share/UnitCell/__init__.py and to look inside the Chimera.app folder click on its icon with the ctrl key held and select "Show Package Contents". Tom > *From: *Rachel Karchin > *Date: *March 4, 2008 5:42:36 PM PST > > Me again. Is there a way to get the coordinates of the unit cell > vertices or the plane equation from Chimera running through a python > script? > > Tx!! > > -- rk # Get currently opened PDB models from chimera import openModels, Molecule mlist = openModels.list(modelTypes = [Molecule]) # Print crystal unit cell axes for each molecule. from PDBmatrices.crystal import crystal_parameters, unit_cell_axes for m in mlist: a, b, c, alpha, beta, gamma, space_group, zvalue = \ crystal_parameters(m.pdbHeaders) a_axis, b_axis, c_axis = unit_cell_axes(a, b, c, alpha, beta, gamma) print m.name, 'unit cell axes:' print ' a axis = %8.3f %8.3f %8.3f' % tuple(a_axis) print ' b axis = %8.3f %8.3f %8.3f' % tuple(b_axis) print ' c axis = %8.3f %8.3f %8.3f' % tuple(c_axis)

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Step through trajectory from command line?
by Kristina Furse 05 Mar '08

05 Mar '08

Hi- Can you advance a trajectory by one frame from the command line, or do you have to use the controls in the MD Movie panel? Thanks, Kristina -- Kristina Furse Postdoctoral Research Associate 262 Stepan Chemistry Hall Notre Dame, IN 46556 (574)631-3904

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Graphics cards for Mac
by Tom Goddard 04 Mar '08

04 Mar '08

Here's a comparison of Chimera graphics benchmarks for the current standard PowerMac graphics versus the top-of-the-line graphics: Radeon HD 2600 - no additional cost Quadro FX 5600 - $2850 additional cost Surfaces and meshes: 1.8x faster Volume solid style: size 443**3 vs 325**3. Quadro system was limited 32-bit main memory address space. Molecule: Neglible difference for 34000 atom model in wire, stick, ball and stick, ribbon, sphere styles. The Quadro card has 1.5 Gbytes of memory and will probably have significantly higher performance on solid style volume rendering if the Chimera volume display code is optimized. Probably adding more main memory will not help because the limitation is the 32-bit address space (a limit of Mac OS graphical applications). The Quadro card did not correctly display volume data in solid style with 3d textures (solid rendering 2d texture option turned off) -- displayed a chessboard pattern. Did not test 3d textures on Radeon card. Tom

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scens/movies rendered with povray
by Klaas Decanniere 03 Mar '08

03 Mar '08

Hello, The option to make movies using povray works nice and easy, so I want to push the boundaries a bit :-) - the standard texture included in the .pov files has a very simple finish - is there an easy way to include a spiced-up version? - when not using a "wait" command, several movements (roll, move, scale) are combined. When using the wait command, movements become separated with a small "hesitation" before the second movement starts. Is there a way to minimize this hesitation? Thanks, Klaas P.S.: if you know why powerpoint would play a movie fine 3 or 4 times in a row and then fail after that (nothing else changes, except maybe time), please let me know.

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saving positions
by William Jeffrey Triffo 03 Mar '08

03 Mar '08

hello, if I have used 'savepos' to save several orientations in a chimera session, is there a way to list these positions if I have forgotten what I named some of them? thanks, -Jeff

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Re: [Chimera-users] longer bonds in image
by Elaine Meng 03 Mar '08

03 Mar '08

Hi Bala, This is an expected behavior of Chimera: the ribbon is a smoothed path that does not go exactly through the atom positions. When ribbon is shown, the default is to simply draw the longer or shorter bonds where the ribbon is farther from or closer to the displayed atoms (ribose/base or amino acid side chain) than are the backbone atoms that the ribbon represents. However, there are ways to change the behavior: (A) use the command "ribbackbone" to allow display of both backbone atoms and ribbon. This will not make any bonds look longer or shorter, but it is usually ugly because the ribbon is not in the same place as the backbone atoms. http://www.cgl.ucsf.edu/chimera/docs/UsersGuide/midas/ribbackbone.html (B) with Ribbon Style Editor, "Residue Class" section, you can set which atoms control the ribbon path and which are hidden automatically (by default, without using "ribbackbone") when ribbon is shown: http://www.cgl.ucsf.edu/chimera/docs/ContributedSoftware/ribbonstyle/ ribbonstyle.html I hope this helps, 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 P.S. you can send attachments such as images to chimera-users, but the message will not appear until the moderator has a chance to approve it... just be patient and it will be sent! On Mar 2, 2008, at 9:00 PM, bala wrote: > -----Original Message----- > From: bala > Sent: Fri 2/29/2008 12:13 PM > To: chimera-users(a)cgl.ucsf.edu > Subject: longer bonds in image > > Hi all, > > Thank you for the suggestions for my previous query. > > When the ribbons are displayed for the backbone of a RNA molecule. > Some of the bonds look longer than usual. Herewith i have attached > the image of a RNA molecule in which residues colored in cyan have > some bonds longer in appearance. Kindly help me to get this of this. > > Thanks, > Bala

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Chimera-users March 2008