April 2017 - Chimera-users - RBVI Mailing Lists

Hidden water molecules
by Michael Sharkey 11 Apr '19

11 Apr '19

Hi I'm trying to visualise water molecules associated with the crystal structure of an enzyme (specifically PDB ID: 1C1D). They're listed when I open the pdb as a text file using WordPad, but I can't for the life of me get them to appear on the screen when I try to visualise the structure in Chimera (v. 1.10.2). What am I missing? Thanks in advance Mike --

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Constrainted fitting
by Christoph Wigge 22 Mar '19

22 Mar '19

Dear all, I would like to fit two protein monomers that form a dimer into an em density map. I know from previous mutagenesis studies that the binding takes place with two tryptophan residues and the counterpart binding pocket. How can I set this interaction as fixed so that chimera fits the rest of the molecule according to the density map without continuously changing this part of the essential protein protein interaction? I would like to fit that interaction manually and then exclude it from the automatic procedure. Thank you very much in advance. Bests Christoph Wigge

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translation and rotation in MATLAB using transformation matrices from chimera
by Oleksiy Kovtun 10 May '17

10 May '17

Dear all, I need to merge two maps in MATLAB using alignment data from chimera. Inputs: two maps of the same box size, origin. I use matrixget - to report translation and rotation matrices for the aligned map . Translation operation works well when transferred into MATLAB (briefly, translation matrix gets converted in eulers and pased on to tom_rotate command in MATLAB, TOM package). However the x y z translation coordinates (the fourth column top to bottom in matrixget - output) are way off the real translation when using tom_shift command in MATLAB, TOM. I found out that if I open the rotated map and fit it again, it gives close to correct translation matrix. What's going wrong here? Does anyone have a solution how to overlay 3D arrays in MATLAB using chimera-reported transformation matrices? Many thanks, Oleksiy Dr Oleksiy Kovtun Research Fellow Briggs group MRC Laboratory of Molecular Biology Francis Crick Avenue Cambridge CB2 0QH UK Tel: + 44 1223 267551 Email: okovtun(a)mrc-lmb.cam.ac.uk Dr Oleksiy Kovtun Research Fellow Briggs group MRC Laboratory of Molecular Biology Francis Crick Avenue Cambridge CB2 0QH UK Tel: + 44 1223 267551 Email: okovtun(a)mrc-lmb.cam.ac.uk

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calculate FSC curve between experimental cryo EM map and model
by #AHMED TOFAYEL# 08 May '17

08 May '17

Dear all, If I want to calculate FSC curve between experimental cryo EM map and model, what is the correct procedure to do so? I will explain what I have tried so far. Although I have variable local resolution in my map, according to FSC=0.143 criterion I have a 4 Ang map (say 1.mrc), I have used 'molmap' command in Chimera to generate a simulated map at 4 Ang. Then I used "vop resample" to take care of the pixel and box values ( then saved as 2.mrc). Thereafter, I have used "e2proc3d.py 1.mrc fsc.txt --calcfsc=2.mrc and plotted the fsc.txt file to get the curve. I am not sure if I am on the right track. My pixel size is 1.28. Best regards, Tofayel

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Contact Maps (RRdistance Maps) questions:
by Nicole Persky 03 May '17

03 May '17

Hi All, I've just found the RRdistance Map function on Chimera and would like to compare between structures. I would like to: 1- make contact map of protein 1 to protein 1 with a cutoff of about 6 angstroms 2- make a contact map of protein 2 to protein 2 with a cutoff of about 6 angstroms 3- compare these two contact maps using the colors available for the whole contact map. I can only seem to compare the ENTIRE contact map of protein 1 to the ENTIRE map of protein 2, whereas I'd like to mask any contacts over 6 angstroms. Alternatively, if anyone knows of a way to export residue lists of contacts from the contact map site I could just compare them that way. ALSO: Anyone know of a way to map defined attributes onto a contact map? Thanks so much! Sincerely, Nicky

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assistance
by Arthur Szabo 01 May '17

01 May '17

I asked this question several months ago, but rarely have applied the answer. I have a structure that has a long stretch that is disordered. In the structure it appears as a dashed line. If I highlight this section of the total sequence and then apply a color (red) the whole structure is then colored red. So how can I make the dashes slightly larger, and secondly color that stretch of dashes with a particular color without coloring the rest of the molecule? Thank you Arthur G. Szabo

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Re: [Chimera-users] [chimerax-users] animations
by Elaine Meng 01 May '17

01 May '17

> On Mar 6, 2017, at 6:21 AM, Giorgio Luciano <giorgio.luciano(a)gmail.com> wrote: > > Hello ! In the effort to create a more integrated pipeline with vastly used 3d software (I use mainly C4D and modo) is there a way to export animation from chimera in a format that other software can interpret. To make an example. If I wiggle a molecule in chimera, can I export the animation in a format that does not lot this info ? And eventually are there plan to create this feature in chimeraX ? > Giorgio Hi Giorgio, Chimera supports several export formats, see “File… Export Scene” in the menu or the “export” command. <http://www.rbvi.ucsf.edu/chimera/docs/UsersGuide/export.html> <http://www.rbvi.ucsf.edu/chimera/docs/UsersGuide/midas/export.html> However, these are for individual conformations, not for a whole animation, so you’d have to export at each step. Although ChimeraX is in early development, currently the “save” command formats include STL and X3D. The command “save formats” lists all the formats that can be saved. <http://rbvi.ucsf.edu/chimerax/docs/user/commands/save.html> These may be subject to the same limitations mentioned in the Chimera manual links above. 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

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independent rotation of multiple models
by Stefano Luciano Ciurli 01 May '17

01 May '17

Hello, if I have more than one structure in the same session, is there a way to rotate all models together along their respective axes (for example their intrinsic y-axis) without having to do so after selecting each individual model from the model panel? Regards and thanks, Stefano Ciurli

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coloumbic coloring when surface can't be calculated?
by Oliver Clarke 29 Apr '17

29 Apr '17

Hi, I have a structure (well, lots of structures) for which surface calculation fails in Chimera. I can rescue surface calculation using the ‘grid’ option (e.g. surf #0 grid 1), but then I can’t figure out how to apply coulombic coloring to that surface. I could use APBS, but PDB2PQR seems to choke on especially large/complicated structures. Is there any way around this? Would it be possible to export the coloumbic potential as a .dx file and use that for electrostatic surface coloring? Cheers Oli

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Pipes and Planks
by chemocev marker 27 Apr '17

27 Apr '17

Hi Chimera users I am wondering if its possible to assign 2 different color to 2 different helix when use the pipes and planks option in depiction. best Jiri

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