- Chimera-users - RBVI Mailing Lists

Control of the volume viewer from the command line
by Lukas Palatinus 28 Nov '06

28 Nov '06

Hello all, I am trying to make a movie showing an evolution of an electron density map during an iterative optimization. For each optimization step I have one density map as volume data in xplor format. I depict the maps using the volume viewer, where I can set the number and level of the isosurface thresholds as well as their color. However, each newly opened map opens with default threshold setting, which is not suitable for my purposes. I make the movie using a command file of the type: open density1.xplor movie record wait 10 movie stop close 0 open density2.xplor movie record wait 10 movie stop ... I would need to be able to control the properties of the isosurfaces of the newly opened map from the command line or from the script file, or find a way to preserve the properties set for the first map in all subsequently opened maps. The search in Chimera manual did not lead me anywhere. Could anyone give me a hint how to proceed? With best regards Lukas Lukas Palatinus Laboratoire de Cristallographie EPFL Lausanne Tel.: +41 (0)21 693 0639 mailto: palat(a)fzu.cz

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Re: [Chimera-users] Get angles in degree out of Rotation matrix
by Thomas Goddard 27 Nov '06

27 Nov '06

Hi Michael, Perhaps you can compare the orientation between the exact symmetric placement of a chain and the actual position by measuring the translation and rotation angle needed to align the two. By rotation angle I mean that any rotation can be represented as a rotation about a single axis (which depends on the rotation). I do not understand what you mean by rotation angles about x, y and z axes. As I mentioned that depends on the order of the rotations and therefore is rarely used. In the Chimera match command or matchmaker tool the optimal rotation matrix is computed -- it is *not* decomposed into separate x, y and z rotations during that calculation. I suppose if your system has symmetry about the z axis you could ask what rotation about z best aligns a chain with the exact symmetric chain location. In other words, only a z-axis rotation rather then rotation about an arbitrary axis would be allowed. Chimera does not have code for that and I have never heard that number reported. If you spell out precisely what angle is needed I can give better advice on how to get it from Chimera. Tom > From: "Stohr, Michael" <stohr(a)uni-mainz.de> > To: "Thomas Goddard" <goddard(a)cgl.ucsf.edu> > Date: Mon, 27 Nov 2006 09:51:31 +0100 > Subject: AW: Get angles in degree out of Rotation matrix > > Hi Tom, > > Thanks a lot for your description. It does not fit completely my demand. I will rephrase my question, is there a simple way to determine the three angles between the two 3d-structures of two identical chains? The background is that my molecule is not absolutely symmetrical and I want to quantify the asymmetry. So, I want to be able to say, this angle between this two chains differs from ideal symmetry angle by X degrees for different directions (x, y, z). I thought the rotation matrix would be the way to do so, but it does not seem so. I've found a not very precise method by using the distance tool and trigonometric functions. Therefore, if there is no answer for my question it will be ok at first especially I have to finish my theses very soon. By the way, in which order does for example the tool match or matchmaker rotates a structure or is this not predictable? > > Thanks for your afford, > Michael

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Increase/decrease the sphere
by tuhin＠iitk.ac.in 27 Nov '06

27 Nov '06

Dear Chimera users, Could anybody tell me whether there is a way in chimera to increase/decrease the size of the spheres/ball-and-stick in atom display (Action-->Atoms/Bonds-->sphere...). The wireframe has an option in "wire width", is there something like that for the above two options ?? Waiting for yours suggestions. Thanks in advance. Best, TKP

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Re: [Chimera-users] DelPhi
by Elaine Meng 25 Nov '06

25 Nov '06

Hi Stefano, Oh I see - it appears to be a problem with the Mac DelPhi download. I tried getting this myself, and could not run the executable, with this error message (probably the same problem you had): meng% /Users/meng/Desktop/release1.1/exe/delphiMacOSX; exit dyld: /Users/meng/Desktop/release1.1/exe/delphiMacOSX can't open library: /opt/ibmcmp/lib/libxlf90.dylib (No such file or directory, errno = 2) Trace/BPT trap logout [Process completed] I'm not an expert at understanding these messages, but it looks like the executable is looking for some code library that is not there. If you could run the executable successfully, the next step would be to put it in your "path," so that just typing the name of the executable in a Mac Terminal window would run the program. That would allow DelPhiController to connect properly. You would also want to download the DelPhi "sample data" http://luna.bioc.columbia.edu/honiglab/software/DelPhi/data.tar.gz which has charge and radius parameter files that can be used with the program. Sadly, in our current situation, we cannot use the program. I do not have the programming expertise to fix this library problem, but if any of us figures it out, we will definitely let you know. If you do get a fix from the Honig lab, it would be great if you could let me (or chimera-users) know - probably several of us would like to use this software on a Mac. Sorry about the trouble, Best, 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

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DelPhi
by Stefano Ciurli 24 Nov '06

24 Nov '06

Hello, does anyone know how to implement the DelPhi algorithm into Chimera? I am using a Powerbook G4. Thanks a lot Stefano -- ____________________________________________ Stefano Ciurli Professor of Chemistry Laboratory of Bioinorganic Chemistry Department of Agro-Environmental Science and Technology University of Bologna Viale Giuseppe Fanin, 40 I-40127 Bologna Italy Phone: +39-051-209-6204 Fax: +39-051-209-6203 "Fatti non foste a viver come bruti, ma per seguir virtute e canoscenza" Dante Alighieri - Inferno - Canto XXVI "Ihr seid bestimmt, nicht Tieren gleich zu leben, Nein, Tugend zu erringen und Erkenntnis" "Ye were not form'd to live the life of brutes, But virtue to pursue and knowledge high"

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fitting map into map
by Gabor Papai 24 Nov '06

24 Nov '06

Hi, Does anybody know if there is a way to calculate fitting of EM density map into another EM density map? I know how it goes with PDBs, but couldn't figure out how I can do it with maps. Thanks for help in advance, Gabor -- Gabor Papai IGBMC Department of Structural Biology and Genomics 1, rue Laurent Fries, BP 10142 67404 Illkirch, France phone +33-3-90244796 Fax +33-3-88653201 E-mail: papai(a)igbmc.u-strasbg.fr

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question about using swapaa in Chimera
by Ng, David (NIH/NCI) [E] 22 Nov '06

22 Nov '06

Hi, I'm currently learning to use Chimera. I wish to look at specific amino acid mutations in CDKN2A for effects in conformational changes and changes in protein interactions with known partners. When I type the command "swapaa P #0:24" in chimera to mutate arginine 24 to proline in CDKN2A, I get an error message that says "Value error: No connectivity template for residue P" Can you help me with this issue? Thanks. David Ng, M.D. Staff Clinician

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Re: [Chimera-users] Get angles in degree out of Rotation matrix
by Thomas Goddard 20 Nov '06

20 Nov '06

Hi Michael, It is not very common to specify a 3-dimensional rotation in terms of a x-axis rotation, y-axis rotation and z-axis rotation because this decomposition depends on the order of the x, y, and z rotations. If you rotate 90 degrees about the x-axis, then 90 about the y-axis you get a different orientation than if you do the y-axis rotation first followed by the x-axis rotation. Chimera has a routine to produce the rotation axis (a unit vector in 3-dimensions) and rotation angle about that vector corresponding to a 3x3 rotation matrix. You could use that in Chimera with some Python code. If you just want the rotation angle and don't need the axis then the formula is simple Tr(R) = 1 + 2*cos(theta) where Tr(R) = sum of rotation matrix diagonal elements so the rotation angle theta = arccos((Tr(R) - 1)/2) Below I give the Chimera C++ code that also computes the axis. There are corner cases handled by this code for 0 degree and 180 degree rotations. Tom void Xform::getRotation(Vector *axis, Real *angle) const { Real cosTheta = (rot[0][0] + rot[1][1] + rot[2][2] - 1) / 2; if (fuzzyEqual(cosTheta, 1)) { *angle = 0; (*axis)[0] = (*axis)[1] = 0; (*axis)[2] = 1; return; } if (!fuzzyEqual(cosTheta, -1)) { *angle = degrees(acos(cosTheta)); Real sinTheta = sqrt(1 - cosTheta * cosTheta); (*axis)[0] = (rot[2][1] - rot[1][2]) / 2 / sinTheta; (*axis)[1] = (rot[0][2] - rot[2][0]) / 2 / sinTheta; (*axis)[2] = (rot[1][0] - rot[0][1]) / 2 / sinTheta; return; } *angle = 180; if (rot[0][0] >= rot[1][1]) { if (rot[0][0] >= rot[2][2]) { // rot00 is maximal diagonal term (*axis)[0] = sqrt(rot[0][0] - rot[1][1] - rot[2][2] + 1.0f) / 2; Real halfInverse = 1 / (2 * (*axis)[0]); (*axis)[1] = halfInverse * rot[0][1]; (*axis)[2] = halfInverse * rot[0][2]; } else { // rot22 is maximal diagonal term (*axis)[2] = sqrt(rot[2][2] - rot[0][0] - rot[1][1] + 1.0f) / 2; Real halfInverse = 1 / (2 * (*axis)[2]); (*axis)[0] = halfInverse * rot[0][2]; (*axis)[1] = halfInverse * rot[1][2]; } } else { if (rot[1][1] >= rot[2][2]) { // rot11 is maximal diagonal term (*axis)[1] = sqrt(rot[1][1] - rot[0][0] - rot[2][2] + 1.0f) / 2; Real halfInverse = 1 / (2 * (*axis)[1]); (*axis)[0] = halfInverse * rot[0][1]; (*axis)[2] = halfInverse * rot[1][2]; } else { // rot22 is maximal diagonal term (*axis)[2] = sqrt(rot[2][2] - rot[0][0] - rot[1][1] + 1.0f) / 2; Real halfInverse = 1 / (2 * (*axis)[2]); (*axis)[0] = halfInverse * rot[0][2]; (*axis)[1] = halfInverse * rot[1][2]; } } }

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Re: [Chimera-users] suggestion
by Thomas Goddard 20 Nov '06

20 Nov '06

Hi David, Thanks for your suggestion to add coloring of isosurfaces based on gradient magnitude to Chimera. I think I can add this to the Surface Color tool in an hour or two since the gradient calculation code is already in Chimera (for fitting atomic models in maps). I'll try to put it in soon and send you the code to test. Description of coloring from article: "OpenDX (www.opendx.org) module MAKROVIS was implemented to create masks of different shapes and to analyze disorder in the reconstructions (Figure 1B). For this, isosurface rendering of a given voxel was colored as a function of the maximum density difference between the voxel and its neighbors." Tom > From: "David G. Morgan" <dmorgan(a)ucdavis.edu> > To: goddard(a)cgl.ucsf.edu > Subject: suggestion > Date: Thu, 16 Nov 2006 19:03:50 -0800 > > Tom, > > I have a suggestion for the developers "list of ideas to implement," if > you think there would be enough interest from users and that it is > something that chimera should do. I realize that you get lots of > suggestions, and that some of them are simply outside the realm of what > the chimera developers think chimera is intended to do. But since you > do ask for suggestions, here's my most recent one. > > I'm attaching a recent journal article where the authors used a color > coding scheme to display "order/disorder" regions of an EM > reconstruction. The images are in Fig 1 B and the rather sparse > description of the "algorithm" is a single sentence in the "Image > Processing 3D Reconstruction" section (p 1046). The idea of color > coding some estimate of the better defined regions of a density map is > very nice (and clever), and would be extremely helpful in lots of > situations (my plug for wanting you guys to implement something > similar...). > > The idea behind this is that for any given region of iso-surface, the > density gradient normal to that surface should be a reasonable measure > of how well defined the density is. In other words, a very steep > gradient (e.g., a fast transition between protein and solvent) means > very well defined density and a flat gradient means weakly defined > density (disordered regions, partial occupancy, etc.). The authors > don't do such a complicated calculation, but it seems that what they > implemented at least captures most of this sort of character. > > I think the key to this is that the gradient is calculated "locally." > I've looked at gradients as a function of resolution with the idea of > using it to help chose a proper iso-surface. While it works well with > model data, real reconstructions aren't nearly so well behaved. I > hadn't thought about this in a while, but I think what the authors have > done both helps explain the behavior of my real data (the gradient is > simply too varied) and is a quite useful visualization tool. > > So please think about implementing something like this in the volume > handling tools of chimera. > > David Gene Morgan > Advanced Microscopy & Proteomics > Molecular & Cellular Biology > University of California at Davis > 530 752 2693 (lab) > 530 752 3085 (FAX) > ---- > removed PDF for > > Huiskonen JT, de Haas F, Bubeck D, Bamford DH, Fuller SD, Butcher SJ. > Structure of the bacteriophage phi6 nucleocapsid suggests a mechanism for sequential RNA packaging. > Structure. 2006 Jun;14(6):1039-48.

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Duplicate Atom Serial Numbers
by Albion Baucom 17 Nov '06

17 Nov '06

When I generate a PDB file, and generate symmetry related biological units, I frequently replicate the single structure. When I do this the atoms numbers get duplicated and when I open the structure in Chimera it prints to the screen warning: duplicate atom serial number found: NNNN where NNNN is the duplicate number. The problem with this is it slows down opening the file by a huge factor. I assume that the print statement to the terminal is adding a lot of time to the file reading process. Is there any way around this, or a way to simply turn this off? I am not concerned with the specifics of the duplicate atom numbers. A single error message to alert me the fact that there are duplicate atoms would be enough. Once Chimera is done reading the structure it works fine. Rotations are smooth. Displaying ribbons is quick, etc. This doesn't appear to be a slow down due to atom limitations, but simply the overhead of printing that error message over and over to the console. Of course I am aware that there are BIOMT records to generate symmetry related molecules using a single repeating unit, or I could generate separate PDB files for each repeating unit, but this is a lot more work and bookkeeping when I can use some existing simple programs to simply rotate and translate a single set of coordinates. Thanks Albion

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