- Chimera-users - RBVI Mailing Lists

Data of Slice display
by Jason 19 Mar '08

19 Mar '08

Hi all I am using slice display to plot the profile of density map. That is the function that I want to exam the profile of virus density map without spherical average. Where can I get the data of each dot of profile, so I can plot profile at Excel for further use. Thank you for your help Kind regards Jason Chen -- Open WebMail Project (http://openwebmail.org)

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Average slab thickness
by Tom Goddard 19 Mar '08

19 Mar '08

Hi Jeff, The Chimera mask command code can be adapted to calculate the average thickness of a slab defined by two surfaces. I've attached the adapted Python code. You select the surfaces then open the script and it reports the mean thickness, standard deviation of thickness, min/max thickness and number of thickness samples used. The script contains a projection axis which should be perpendicular to the slab and a grid step which defines the grid spacing. The thickness is measured on a grid perpendicular to the axis and only grid points where the projection axis intersects the surfaces at least twice are used. You have to edit the script (at the bottom) to set the projection axis and grid step to appropriate values. Those values could be automatically set using the Python code of the inertia ellipsoid script I gave you earlier. Tested in Chimera version 1.2498 on a spherical surface. Tom Jeff wrote: > hi Tom, > > I'd like to compute the 'average distance' between two surfaces to > calculate the width of a cellular compartment (have attached an image, > the two surfaces delineating the compartment are colored blue). > > one way that has been suggested to me is to calculate the volume > between the two surfaces, and then just divide by a mean path length > along one of the surfaces. I know that chimera has a volume > calculation tool for an isosurface, and was wondering if I could use > the surfaces you see to do a volume calculation (and, if so, how I > would go about capping those surfaces to create a closed surface). If > able to calculate the volume that way, I could just use the path > length of a contour (which I have) that generated one of the two > surfaces to derive the "average width". > # ----------------------------------------------------------------------------- # Script to calculate average thickness of a slab defined by surfaces. # Adapted from mask command code for Jeff Triffo, March 18, 2008. # # Adapted version of masked_volume() from depthmask.py. # # Only uses first two surface layers along projection axis. # def average_thickness(projection_axis = (0,0,1), grid_step = 1.0, surfaces = None): # Use selected surfaces if none are passed in. if surfaces is None: from Surface import selected_surface_pieces plist = selected_surface_pieces() from Mask.depthmask import surface_geometry surfaces = surface_geometry(plist, tf = None, pad = None) # Determine transform from vertex coordinates to depth array indices from Mask.depthmask import orthonormal_frame fx,fy,fz = orthonormal_frame(projection_axis) from numpy import array, float32, intc, zeros tf = array(((fx[0], fx[1], fx[2], 0), (fy[0], fy[1], fy[2], 0), (fz[0], fz[1], fz[2], 0)), float32) / grid_step # Transform vertices to depth array coordinates. zsurf = [] tcount = 0 for vertices, triangles in surfaces: varray = vertices.copy() from Mask.depthmask import apply_transform apply_transform(tf, varray) zsurf.append((varray, triangles)) tcount += len(triangles) if tcount == 0: return 0,0,0,0,0 from Mask.depthmask import bounding_box vmin, vmax = bounding_box(zsurf) voffset = -(vmin - 0.5) tf[:,3] += voffset from _contour import shift_vertices for varray, triangles in zsurf: shift_vertices(varray, voffset) from math import ceil, floor dxsize = int(ceil(vmax[0] - vmin[0] + 1)) dysize = int(ceil(vmax[1] - vmin[1] + 1)) # Create depth arrays depth = zeros((dysize,dxsize), float32) tnum = zeros((dysize,dxsize), intc) depth2 = zeros((dysize,dxsize), float32) tnum2 = zeros((dysize,dxsize), intc) # Copy volume to masked volume at masked depth intervals. max_depth = 1e37 depth.fill(max_depth) tnum.fill(-1) from Mask.depthmask import surfaces_z_depth any = surfaces_z_depth(zsurf, depth, tnum, None, None) if not any: return 0,0,0,0,0 depth2.fill(max_depth) tnum2.fill(-1) surfaces_z_depth(zsurf, depth2, tnum2, depth, tnum) # Find thicknesses at grid points that intercept surfaces twice. dlist = [] for i in range(dysize): for j in range(dxsize): if tnum[i,j] != -1 and tnum2[i,j] != -1: d = (depth2[i,j] - depth[i,j]) * grid_step dlist.append(d) if len(dlist) == 0: return 0,0,0,0,0 from numpy import mean, std return mean(dlist), std(dlist), min(dlist), max(dlist), len(dlist) # ----------------------------------------------------------------------------- # projection_axis = (0,0,1) grid_step = 1.0 m, sd, mn, mx, n = average_thickness(projection_axis, grid_step) print ('Slab thickness along axis %s sampled at grid spacing %.3g' % (str(projection_axis), grid_step)) print 'Mean %.5g, sdev %.5g, min %.5g, max %.5g, samples %d' % (m,sd,mn,mx,n) from Accelerators.standard_accelerators import show_reply_log show_reply_log()

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Requesting to solve my poblem
by Bharat Yadav 19 Mar '08

19 Mar '08

Hello Sir / Madam Good Evening My name is Bharat Yadav and I am perusing Master's Degree in Bioinformatics from Chaudhary Charan Singh Haryana Agriculrual University - Hisar (India). I am working here on Molecular Modeling. With a long time I am using UCSF Chimera. It is the one of wonderful Molecular visiualization software haivng some very peculear features. Respected Sir / Madam, In my present work I am facing a bit problem. Hoping form you to help regarding this. My problem is as follows. I have generated five models of protein. when I open all these modles these were overlapping each other. I want to view all these five models in a single panel non overlapping. I mean I want to view these 3D models in panel as follows ----------------------------------------- | | | | | | | Model 1 | Model 2 | | | | ----------------------------------------- | | | | | | | Model 3 | Model 4 | | | | ----------------------------------------- | | | | | | | Model 5 | Model 6 | | | | ----------------------------------------- Hope that you now easily understand what actually I want. Please Help me regarding this and mail me its solution or steps or commands for this task. Please free to ask any question. Thanks in anticipation Warm regards from Bharat Yadav

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interface residues
by Francesco Malatesta 17 Mar '08

17 Mar '08

Hello, could anyone help me out with this problem. I would like to exclusively colour interface residues in a dimeric protein represented as spheres or surface. Is this possible? Thank you very much Francesco Malatesta

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preferences - povray - keep input files doesn't
by Klaas Decanniere 17 Mar '08

17 Mar '08

For at least some versions of Chimera, the "keep pov-ray input files" option in the Favorites - Preferences- Pov-ray tab does not work ( .pov files are deleted after rendering during animation) This is true e.g for build 2491 2008/02/11 (Platform: linux2 windowing system x11). Is there a way to force this option? I would like to do some post processing on the .pov files before rendering. An option to generate an animation series .pov files without doing the actual rendering would be even better - how can I do that? Thanks for the help and kind regards, Klaas Decanniere

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segmentation fault - surface rendering
by Michael DiMattia 13 Mar '08

13 Mar '08

Hello, I am trying to surface render a few different proteins within the same Chimera session and I keep encountering a segmentation faullt. I imagine this is due to a memory limit being reached, although I do not know if it is a Chimera parameter that can be increased/overriden. Instead of having the different macromolecules in the same pdb, I have actually split it up into many pdbs and opened them one at a time, surface rendering one at a time. This worked for awhile but it seems I can't even get that far now. Any advice or tips on what I can do? I realize surface rendering is very computationally intensive but I would love to get this to work! Thanks Mike DiMattia

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[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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