April 2014 - Chimera-users - RBVI Mailing Lists

Structure editing: addH
by George Tzotzos 10 Apr '14

10 Apr '14

Hi everybody, I’ve been trying to add hydrogens to a ligand (7-octenoic acid) obtained from docking. Hydrogens are added but not on the carboxyl group. I’m attaching the ligand.pdb for easy reference. I’d appreciate any suggestions regarding this behavior Best regards George

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Request for guidance
by MUHAMMAD RAMZAN MANWAR 08 Apr '14

08 Apr '14

Dear Dr. Ferrin, Hope this email finds you the best of your health. First of all, I did appreciate the effort that You and Your team did in the form of UCSF Chimera. Being the part of academic/government university, I have used Chimera tool for protein modeling and cited in my two articles: one published in JCB-Wiley and other in Hundawi in 2014. Current email I am sending to request for guidance about how can I substitute an amino acid (wild type to mutant residue) within protein 3D model by using Chimera. I will be thankful for your guidance, if possible. With regards Hussain MR PACER-HD, KAU, KSA

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Surprising "measure symmetry" result
by ingvar 08 Apr '14

08 Apr '14

Hello, I fetched entry EMD-2463 from EMDB and issued: measure symmetry #0 nMax 24 and got the result "Symmetry emd_2463.map: C13, center 64 64 37" Increasing the number of sampling points does not change the result, but if I increase the correlation criteria a little, to say 0.992, I get the expected C12 symmetry. Also if I change the contour level to 0.05, the author recommended level, I get C12 again. Looking at the volume at several different contour levels, it is difficult to see how it could be considered C13, and also how it would go from C13 to C12. Kind Regards, Ingvar Lagerstedt -- Ingvar Lagerstedt European Bioinformatics Institute (EMBL-EBI) European Molecular Biology Laboratory Wellcome Trust Genome Campus Hinxton Cambridge CB10 1SD Tel: +44 (0)1223 492533

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Docking ligands and protein using Chimera
by Sook Wong 08 Apr '14

08 Apr '14

Good morning, I am currently doing research with a professor for protein-ligand structure and would like to dock the receptor molecule (pdb file of the protein) and ligands (pdb file of the sugars). Since I have both the structure files from Chimera, how would I predict and assume which orientation bound to each other forming a stable complex? Looking forward to hear from you. Thank you so much! Sincerely, Sook Y Wong Chemical and Biomolecular Engineering '14 A. James Clark School of Engineering University of Maryland, College Park, MD 20742 swong18(a)terpmail.umd.edu

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Calculating SAS and SES with Chimera-MSMS wrap
by Jaime Rodríguez-Guerra 07 Apr '14

07 Apr '14

Dear Chimera dev team, I am trying to use your MSMS wrapper to compute some SAS/SES values for a given set of atoms. As suggested in a previous post in this list, I've taken a look into Measure.measure.buried_area() and I think I've got it, but just wanted to make sure. Here is my current procedure: ``` import chimera, Measure, MoleculeSurface atoms = chimera.selection.currentAtoms() xyzr_data = Measure.measure.atom_xyzr(atoms) surfaces = MoleculeSurface.xyzr_surface_geometry(xyzr_data) for i, a in enumerate(atoms): print "Atom: {0}, SAS: {1}, SES: {2}".format(a.name, surfaces[3][i,0], surfaces[3][i,1]) ``` Is this OK? I don't know how to handle all that output that MSMS is giving back! Thanks in advance, Jaime.

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Re: [Chimera-users] Reaction Mechanism Movie
by Eric Pettersen 07 Apr '14

07 Apr '14

On Apr 5, 2014, at 1:06 PM, Moses Adenaike wrote: > Dear Dr. Pettersen, > I am wondering how I would go about making a moive detailing a biochemical reaction. For example, I want to show a DNA polymerase reaction, essentially a ligation between the backbone of two nucleotides. How would I go about doing so? I know chimera has a make new bond function but I haven't been too successful at getting that to work. Hi Moses, It is typically better to send questions like this to the chimera-users mailing list than to me directly so that others can benefit from the answer and in case others on the list have more expertise on the topic than I do. The simplest method is to decide which frame# you want the bond to start existing and use the "Define script…" entry in MD Movie's Per-Frame menu to define a one-command script to execute at that frame. For example, if you wanted a bond between :337.A@P and :338.A@O3' to exist starting with frame 53, in the Per-Frame dialog you would set "Interpret script as" to "Chimera commands" and enter as your script: #53 bond :337.A@P :338.A@O3' There is also a hidden capability in Chimera to compute all bonds on a per-frame basis. I can tell you how to access that if it turns out you really need it. However, for the purpose of making a movie it might be nice to have a more "continuous" representation of the bond forming than just the binary on/off that the above approaches give you. I have attached a Python script that you can use the Per-Frame dialog (with "Interpret script as" set to Python, and reading in the script with the "Insert text file…" button) to have a bond form (by starting out very thin and becoming thicker) as two designated atoms approach each other. There are some values at the top of the script that you can edit to make it work best in your situation. There is a distance value for when the bond begins to exist (noBond, default 3.5) and when it reaches full size (fullBond, default 2.0). There is a two-member list of residue IDs (resIDs) for the atoms involved in the bond, and a list of atom names (atomNames). Let me know if you need more help than this. Hmmm, this all assumes you have a trajectory of the reaction. You may have to use the Morph Conformations tool to create such a trajectory if you don't have one already. --Eric Eric Pettersen UCSF Computer Graphics Lab http://www.cgl.ucsf.edu

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presets-interactive 3-hydrophobicity surface- those water molecules stay!
by Ying-Chieh Sun 06 Apr '14

06 Apr '14

Hi, I did a simulation using Amber package and saved a snapshot into its pdb file, and use Chimera to open it. The pdb file contains a protein-ligand complex plus a box of about 20000 TIP3P water molecules. When I pressed presets-interactive 3-hydrophobicity surface, there are 8 water molecules stayed close to the ligand binding site. I am wondering how these 8 water molecules were determined? The reason I ask is because we are trying to find a way to determine 'crystal (or say, ordered) water molecules'. This presets-interactive 3-hydrophobicity surface seems to perform this function in some way. Thank you for your help. Ying-chieh Ying-Chieh Sun, Professor of Computational Chemistry Chemistry Department National Taiwan Normal University Taipei, Taiwan 11617 Tel: +886-2-7734-6215 Fax: +886-2-2932-4249

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Resolution of .stl file of ribbon representatiom
by Gavin Whittaker 04 Apr '14

04 Apr '14

Dear all, I'm in the process of 3d printing a large protein in ribbon format; I've generated the .stl file, but the resolution of the mesh that Chimera creates means that the resulting file is too large to use easily. I've managed to use other software to reduce the resolution of the mesh, so I /can/ now get around the problem, but can anyone tell me if it's possible to reduce the resolution of the mesh in Chimera to save me a step for future models? I know how to reduce the resolution of a surface mesh, but files of ribbon representations remain obstinately large. One method I've used that gives limited results is to simplify the cross-sectional form of the ribbon, but I wonder, am I missing something obvious and more effective? thanks! Gavin

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query
by Bhaskar Bagchi 04 Apr '14

04 Apr '14

Respected Sir I want to calculate surface area of different atoms in a molecule. Is it possible in chimera? Please help me. Thanking you Yours faithfully, Bhaskar Bagchi Research Scholar Raiganj University College Email: bhaskarbagchi(a)gmail.com

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ellipsoid main axis alignment ?
by Hugo J Bohorquez 03 Apr '14

03 Apr '14

Hi, I am writing a script in python for generating a series of ellipses linking the nuclei a molecule. Every ellipsoid should be positioned at a specific location *P* = (X,Y,Z) and should be aligned with the orthonormal vectors describing its main directions-*A*, *B*, *C*. However, when I create an ellipsoid with shape_command it gets located correctly at *P* but it is aligned with the global axis. I can't find a general way to reorient an object so its original axes point along the vectors *A*, *B*, and *C*. I will appreciate any suggestion how to do it. -- Hugo J Bohórquez <https://sites.google.com/site/hugojbohorquez/home>, PhD *Investigador* Grupo de Biofísica Fundación Instituto de Inmunología de Colombia TEL. +57 +1 -3158920 Ext. 122 CEL. +57 315-6169069 *The Pauli energy grows exponentially with the electronic localisation <http://dx.doi.org/10.1080/00268976.2013.836605>*

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Chimera-users April 2014