- ChimeraX-users - RBVI Mailing Lists

Re: [chimerax-users] Placing a ligand in a protein structure from PDB
by Elaine Meng 30 Nov '22

30 Nov '22

> On Nov 30, 2022, at 7:41 AM, Amit Kugler <amit.kugler(a)kemi.uu.se> wrote: > > Hej Elaine, > > I found you on the ChimeraX website, and I have a question. > > I have a PDB file of my protein, but not showing a ligand. > > I am wondering if there a way I can add a ligand to the active site of the protein and write out the new PDB file on ChimeraX? > > Best regards, > Amit > Hi Amit, We recommend sending questions to chimerax-users(a)cgl.ucsf.edu (CC'd here) to make it more likely you get a response. Not sure what you mean by add a ligand. Sure you can open a file of a ligand and open a file of the protein, and then combine them into one model, and then save. But probably you want to put the ligand in some sensible position, which could be done by moving it individually by hand, or by using some docking program. ChimeraX does not do docking. You would have to use some docking program (Glide, DOCK, Gold, Autodock, Autodock Vina, etc.) and then open the output from that docking program in ChimeraX. Moving models by hand, see this previous post: <https://www.rbvi.ucsf.edu/pipermail/chimerax-users/2017-November/000157.html> There is a "combine" command to combine the two separate models into a new single model, and "save" (or menu File... Save) to save the resulting combined model as a PDB file. <https://rbvi.ucsf.edu/chimerax/docs/user/commands/combine.html> <https://rbvi.ucsf.edu/chimerax/docs/user/commands/save.html#pdb> Or maybe you don't have a structure of the ligand. If there is some other PDB structure that contains it you can open that structure and delete all the rest of the atoms, or if you can find it in PubChem you can try fetching by PubChem ID into ChimeraX, e.g. command open pubchem:12120 <https://rbvi.ucsf.edu/chimerax/docs/user/commands/open.html#fetch> I hope this helps, Elaine ----- Elaine C. Meng, Ph.D. UCSF Chimera(X) team Department of Pharmaceutical Chemistry University of California, San Francisco

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font size on the task bar
by Krishnan Raman 30 Nov '22

30 Nov '22

Is it possible to change the font size(larger) on the first line of the of the taskbar file…edit select etc… For viewing at from a distance on a big screen? Thanks Krish Sent from Mail<https://go.microsoft.com/fwlink/?LinkId=550986> for Windows CONFIDENTIALITY NOTICE This email, including any attachments, may contain confidential or legally privileged information that is intended only for the individual or entity to whom it is addressed. If you are not the intended recipient, please be advised that any dissemination, distribution or copying of this email and any attachment is strictly prohibited. If you have received this email in error, please reply to the sender so that BioCryst Pharmaceuticals, Inc. can take corrective measures and then permanently delete this email and any attachment, including any printed copies. Thank you.

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tile and 2dlabels
by Krishnan Raman 29 Nov '22

29 Nov '22

Hi guys, Trying to show multiple binding protein sites on a large protein. Could successfully make footprints on the protein in different colors on the protein for different binding sites. Was trying to include binding constants as 2dlabels with each model protein. How to associate these labels with models to tile them along with the models? Combining the models (combine on (2dlabel model and structure models did not work.) Trying to use tile command with the 2dlabels to show IC50’s with the individual proteins. What is best way to do this… May be use the label command? Thanks Krish Sent from Mail<https://go.microsoft.com/fwlink/?LinkId=550986> for Windows CONFIDENTIALITY NOTICE This email, including any attachments, may contain confidential or legally privileged information that is intended only for the individual or entity to whom it is addressed. If you are not the intended recipient, please be advised that any dissemination, distribution or copying of this email and any attachment is strictly prohibited. If you have received this email in error, please reply to the sender so that BioCryst Pharmaceuticals, Inc. can take corrective measures and then permanently delete this email and any attachment, including any printed copies. Thank you.

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chimerax hbonds batch analysis
by Visvaldas K. 29 Nov '22

29 Nov '22

Dear ChimeraX wizards, I was trying to generate hbond analysis via nogui, by issuing "chimerax --nogui --script "myscript.cxc", where in the script I put the following commands: open /Users/visvaldas/temp0000.pdbselect /B hbonds sel saveFile /Users/visvaldas/temp00.hbonds restrict cross batch true quit However, something is wrong with hbonds line since I am getting this error:Executing: runscript myscript.cxc Traceback (most recent call last): File "/Applications/ChimeraX-1.4.app/Contents/Library/Frameworks/Python.framework/Versions/3.9/lib/python3.9/site-packages/chimerax/core/scripting.py", line 83, in open_python_script code = compile(data, stream.name, 'exec') File "myscript.cxc", line 4 hbonds sel saveFile /Users/visvaldas/temp00.hbonds restrict cross batch true ^ SyntaxError: invalid syntax What I am doing wrong? (Also, when using GUI, the hbonds line was much longer, so I deleted those reveal, color, etc entities to make it more relevant to batch. (The "long" line hbonds sel saveFile /Users/visvaldas/temp00.hbonds color #fffb00 dashes 5 restrict cross reveal true retainCurrent truefrom the GUI does not work either) Best wishes, Visvaldas

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Cα distance per residue in alignment
by Michael Habeck 29 Nov '22

29 Nov '22

Dear ChimeraX forum, I'm interested in getting the distance between Cα for all residues in an alignment. I've noticed that the Cα RMSD values in the txt file obtained from the header of the sequence alignment created by matchmaker via sequence header rmsd save are different from the distances measured using the rmsd or distance command. The Cα distance measured is approx. 41% higher across the entire alignment than in the saved output. When selecting a pair of aligned residues from the alignment viewer, the distance shown does not match the one in the output file but the distance measurement. I've attached a file with the respective distances for the alignment of chains A in 3c4f and 3gqi as an example. Not sure if this is a misunderstanding from my side or a bug, yet I'd greatly appreciate a clarification of the differences. With thanks in advance and best regards, Michael

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Align with specific atoms (but against all other molecules)
by Kim, Doo Nam 28 Nov '22

28 Nov '22

Hi, I’ve used align #2/X:1 @CA,O,C,N to #1/X:1 @CA,O,C,N align #3/X:1 @CA,O,C,N to #1/X:1 @CA,O,C,N align #4/X:1 @CA,O,C,N to #1/X:1 @CA,O,C,N … to align #2 molecule against #1 molecule with backbone atoms #3 molecule against #1 molecule with backbone atoms #4 molecule against #1 molecule with backbone atoms etc… However, how can I align all rest molecules (e.g. #2~#100) against #1 molecule with backbone atoms at once in chimeraX? I’ve used align all toAtoms #1 matchAtomNames true align all toAtoms #1 matchNumbering true to align all molecules to #1 molecule at once. However, with this command, I cannot specify to use backbone atoms (e.g. CA,O,C,N) only when aligning. I think that there should a 1 line command that aligns all molecules with specific atoms only or there is chimeraX equivalent python script as from chimera import runCommand as rc # use 'rc' as shorthand for runCommand from chimera import replyobj # for emitting status messages Best, Doo Nam

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input delay on one computer and only for ChimeraX
by Barbara S Holme 28 Nov '22

28 Nov '22

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Re: [chimerax-users] [Chimera-users] Writesel command in chimeraX
by Elaine Meng 28 Nov '22

28 Nov '22

Hi Prathvi, Please use the chimerax-users(a)cgl.ucsf.edu address to ask ChimeraX questions (instead of chimera-users(a)cgl.ucsf.edu) so that users will not be confused about which program we are discussing. In ChimeraX you can use the "info" command to report the selection to the Log, as detailed in this previous post. <https://www.rbvi.ucsf.edu/pipermail/chimerax-users/2022-July/003963.html> "info" help <https://rbvi.ucsf.edu/chimerax/docs/user/commands/info.html> It does not have an option to save a file. Instead you have to save the ChimeraX Log in another step. You can use "log clear" before you use "info" and then "log save" to save to HTML file. "log" help <https://rbvi.ucsf.edu/chimerax/docs/user/commands/log.html> I hope this helps, Elaine ----- Elaine C. Meng, Ph.D. UCSF Chimera(X) team Department of Pharmaceutical Chemistry University of California, San Francisco > On Nov 26, 2022, at 5:04 AM, Prathvi Singh via Chimera-users <chimera-users(a)cgl.ucsf.edu> wrote: > > Hi Elaine, > > Is the writesel command available in chimeraX because I could not find it in the Actions menu? > If not, then is any equivalent available apart from the command which saves selection as a new PDB file? > > Thanks once again in advance

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how to remove axes?
by Francisco Murphy Pérez 26 Nov '22

26 Nov '22

After loading a mtz file, 3 axes appear in the middle of the screen. How do I remove them? Thanks

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Display sequence alignment from structure alignment
by James H Naismith 25 Nov '22

25 Nov '22

In Chimera I can sort of print out a sequence alignment based on structural superposition. (Match-align) I can make a very nice structural superposition of very unrelated proteins with matchmaker, all I want to do is print out the resulting sequence alignment (where residues are with y A of each other) Any help gratefully received. With best wishes Jim Division of Structural Biology, Roosevelt Drive, Oxford, OX3 7BN james.naismith(a)strubi.ox.ac.uk Pronouns: he, him, his

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Opening .xyz file in ChimeraX
by Carina Luo 23 Nov '22

23 Nov '22

Hello, I am trying to open an .xyz file in ChimeraX. I installed SEQCROW (1.5.9) as prompted, but ChimeraX still says "Opener for format 'XYZ file' is not installed; see log for more info." Here is the output I got when I installed SEQCROW (1.5.9): Downloading bundle SEQCROW-1.5.9-py3-none-any.whl Errors may have occurred when running pip: pip standard error: --- [notice] A new release of pip available: 22.2.2 -> 22.3.1 [notice] To update, run: C:\Program Files\ChimeraX\bin\ChimeraX.exe -m pip install --upgrade pip --- pip standard output: --- Looking in indexes: https://pypi.org/simple, https://cxtoolshed.rbvi.ucsf.edu/pypi/ Processing c:\users\user\downloads\seqcrow-1.5.9-py3-none-any.whl Requirement already satisfied: jinja2 in c:\program files\chimerax\bin\lib\site-packages (from SEQCROW==1.5.9) (3.1.2) Collecting Send2Trash Downloading Send2Trash-1.8.0-py3-none-any.whl (18 kB) Requirement already satisfied: ChimeraX-Core<=1.5,>=1.2 in c:\program files\chimerax\bin\lib\site-packages (from SEQCROW==1.5.9) (1.5rc202210312311) Requirement already satisfied: scipy in c:\program files\chimerax\bin\lib\site-packages (from SEQCROW==1.5.9) (1.9.0) Requirement already satisfied: psutil in c:\program files\chimerax\bin\lib\site-packages (from SEQCROW==1.5.9) (5.9.1) Requirement already satisfied: MarkupSafe>=2.0 in c:\program files\chimerax\bin\lib\site-packages (from jinja2->SEQCROW==1.5.9) (2.1.1) Requirement already satisfied: numpy<1.25.0,>=1.18.5 in c:\program files\chimerax\bin\lib\site-packages (from scipy->SEQCROW==1.5.9) (1.23.1) Installing collected packages: Send2Trash, SEQCROW Successfully installed SEQCROW-1.5.9 Send2Trash-1.8.0 Could you please help me figure out what I still need to do in order to successfully open .xyz files in ChimeraX? Sincerely, Carina

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How do you submit a sequence text file to BLAST/Modeller in ChimeraX?
by Ralph Loring 23 Nov '22

23 Nov '22

Hi, When I was using Chimera and wanted to use Modeller, I would go to sequence/Blast, paste in my sequence text file, Blast and then pick homologous structures and then connect to Modeller. Both Blast and Modeller appear to be present in ChimeraX, but I can't see how to enter my text file. Is everything supposed to go to AlphaFold now? Are there any tutorials on how to use Modeller in ChimeraX? Thanks! P.S. Hope you have a Happy Thanksgiving! I'm not planning on doing anything with this until after the holidays, so don't rush in answering. Ralph Lorini Ralph H. Loring Associate Professor of Pharmacology Department of Pharmaceutical Sciences 166 TF Northeastern University 360 Huntington Avenue Boston, MA 02115 USA 617-373-3216 office 617-373-8886 fax r.loring(a)northeastern.edu

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Developing a ChimeraX bundle - accessing programmatically ChimeraX(GUI open) session
by Stylianos Iliadis 23 Nov '22

23 Nov '22

Hello, I would like to develop a small bundle-plugin for automatically annotating residue labels in protein structures. I tried to access ChimeraX via command line when ChimeraX was running (GUI open) with an opened protein structure in order to study the structure objects hierarchy( chain ->residue ->atoms). This would help me understand it better and code accordingly. Unfortunately, I didn’t manage to do so. Could you please suggest me a way, a page or terminal where I could read more about the internal structure of ChimeraX and if possible to programmatically access a session when it’s running in ChimeraX. Kind regards, Stel Iliadis

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suggestion
by Hassan, Sergio (NIH/NIAID) [E] 22 Nov '22

22 Nov '22

Hello, I recently requested via Phil Cruz the 'tile' command, which I learned it was recently introduced. I have been using it successfully. However, there are two points I would like to bring to your attention (I asked Phil to ask you, but not sure he reached out) 1) when a session is saved as .cxs and I quit the program, after opening it again, the most important feature of the 'tile' command (rotations around each own axis) is lost. The tile distribution is still there, but now the entire thing rotates around a common axis. I need to apply 'tile' again to make it work, but this resets all the modifications I made in the saved session (these modifications include those in point 2 below). 2) any chance to add an argument to the 'tile' command so that the default spatial distribution, which assigns a 'distance' between near neighbors, can be adjusted with, say, 'zoom in" or "zoom out" or crowd in/out? I noticed the default puts each panel too far away from its neighbors for my taste, so I need to "move" them to make them look closer to one another. thanks s _____________________________________ Sergio A. Hassan https://bioinformatics.niaid.nih.gov/cmm/ BCBB/NIAID/NIH/DHHS 301 761 7221 (office) 301 741 5579 (mobile)

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Re: [chimerax-users] Export pLDDT scores
by Tom Goddard 22 Nov '22

22 Nov '22

Hi Asmahan, The pLDDT scores for an AlphaFold prediction are in the bfactor column of the PDB atomic model file. Here is an example of lines from such a file where the value 85.53 is the pLDDT for residue 1. ATOM 1 N ASP B 1 -0.818 -36.026 -12.912 1.00 85.53 N ATOM 2 CA ASP B 1 0.545 -35.783 -13.373 1.00 85.53 C ATOM 3 C ASP B 1 0.706 -34.352 -13.882 1.00 85.53 C The bfactor is assigned to every atom. But pLDDT is only assigned for each residue and measures CA position so you might want to look at only the CA lines. $ grep CA ~/Downloads/ChimeraX/AlphaFold/prediction_14/af252_unrelaxed_rank_1_model_2.pdb ATOM 2 CA ASP B 1 0.545 -35.783 -13.373 1.00 85.53 C ATOM 10 CA CYS B 2 1.983 -32.130 -13.721 1.00 95.45 C ATOM 16 CA PRO B 3 3.029 -30.770 -17.151 1.00 93.20 C ATOM 23 CA SER B 4 6.629 -31.094 -18.066 1.00 93.36 C You can also write the values into a ChimeraX attribute file using ChimeraX commands select #1@CA save ~/Desktop/plddt.defattr attrName bfactor models #1 selectedOnly true and that file looks like the following attribute: bfactor recipient: atoms match mode: 1-to-1 /A:1@CA 56.150001525878906 /A:2@CA 53.33000183105469 /A:3@CA 53.59000015258789 /A:4@CA 59.380001068115234 documentation here https://www.cgl.ucsf.edu/chimerax/docs/user/commands/save.html#attributes Tom > On Nov 22, 2022, at 7:08 AM, Asmahan Alghamdi <Asmahan.Alghamdi(a)nottingham.ac.uk> wrote: > > Dear Tom, > I hope you are well. I was wondering if there is away to export pLDDT scores of the best predicted model of a protein using ChimeraX e.g. 1.5 (which I am using in my investigations)? > > Thank you very much. > Asmahan

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Zoom over frames
by Krishnan Raman 21 Nov '22

21 Nov '22

Hi , Can I have the zoom command execute over several frames? Thanks Krish

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Re: [chimerax-users] [Chimera-users] Coloring the unit cell box
by Elaine Meng 21 Nov '22

21 Nov '22

(switching to chimerax-users address since this is all about ChimeraX, not Chimera) Sorry no, there is no linewidth setting on the unit cell outline box. However, you can "fake it" by selecting that model so that there are green outlines to show the selection, and then changing the selection-outline color and width: (1) select the outline box model, e.g. as described in the previous message by checking the selection box in the Model Panel (2) use "graphics selection" command to change the selection-outline color and thickness <https://rbvi.ucsf.edu/chimerax/docs/user/commands/graphics.html#selection> I hope this helps, Elaine ----- Elaine C. Meng, Ph.D. UCSF Chimera(X) team Department of Pharmaceutical Chemistry University of California, San Francisco > On Nov 18, 2022, at 9:12 AM, F.Xavier Gomis-Rüth via Chimera-users <chimera-users(a)cgl.ucsf.edu> wrote: > > Thanks a lot, Elaine, this worked indeed! > Just one final point: how can I make the linewidth larger? When I make a picture, the thin lines of the box disappear. > I understand ChimeraX interpretes these lines as a surface, I can change the colour when choosing surface in the colour blow up. > > On 18/11/22 17:49, Elaine Meng wrote: >> Hi Xavier, >> As far as I can tell, it is exactly the same in ChimeraX as in Chimera. First, make sure you aren't using a very old version of ChimeraX. I tried it in ChimeraX 1.5 release candidate (2022-11-08) just now: >> >> - open your structure that has unit cell information, e.g. 1fav >> >> - in Unit Cell tool (menu: Tools... Higher-Order Structure... Unit Cell) click Outline to show unit cell box >> >> - if you want to change box outline color, can use the same method as described below for Chimera. I wasn't able to select it by Ctrl-click, however, so instead use the selection (hand with green dot) checkbox in the Model Panel to select it, then use Actions... Color... [...]. Or, you can just click the color square in the Model Panel and use the system color chooser to change the color interactively. Screenshot: >> >> <Screen Shot 2022-11-18 at 8.48.02 AM.png> >> >> >> I hope this helps, >> Elaine >> ----- >> Elaine C. Meng, Ph.D. >> UCSF Chimera(X) team >> Department of Pharmaceutical Chemistry >> University of California, San Francisco >> >> P.S. for ChimeraX questions specifically, you may want to use the other mailing list, chimerax-users(a)cgl.ucsf.edu >> >>> On Nov 18, 2022, at 7:03 AM, F.Xavier Gomis-Rüth via Chimera-users <chimera-users(a)cgl.ucsf.edu> wrote: >>> >>> Dear Elaine, >>> I am now trying to get this done in ChimeraX where there is indeed a similar option. Unfortunately, if I proceed as in the instructions >>> I do not get the cell box, in contrast with old Chimera. I also tried through the command line but unsuccessfully. >>> Am I missing something? >>> Thanks a lot in advance, >>> Xavier >>> >>> On 26/10/22 17:45, Elaine Meng wrote: >>>> Hi Xavier, >>>> You can select the box (Ctrl-click on it) and then use menu: Actions... Color... [choose color], then clear selection by Ctrl-click on blank area of window or menu Select... Clear Selection. >>>> I hope this helps, >>>> Elaine >>>> ----- >>>> Elaine C. Meng, Ph.D. >>>> UCSF Chimera(X) team >>>> Department of Pharmaceutical Chemistry >>>> University of California, San Francisco >>>> >>>> >>>>> On Oct 26, 2022, at 1:56 AM, F.Xavier Gomis-Rüth via Chimera-users <chimera-users(a)cgl.ucsf.edu> >>>>> wrote: >>>>> >>>>> Dear all, >>>>> is there a way in Chimera or ChimeraX to get the unit-cell box being drawn in another colour than white? >>>>> This forces the background to be dark.... >>>>> Thanks a lot in advance, >>>>> Xavier >>>>> >>> >> > > -- > <fxgr_signanew.jpg> > _______________________________________________ > Chimera-users mailing list: Chimera-users(a)cgl.ucsf.edu > Manage subscription: https://www.rbvi.ucsf.edu/mailman/listinfo/chimera-users

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Re: [chimerax-users] [Chimera-users] Alphafold
by Tom Goddard 20 Nov '22

20 Nov '22

AlphaFold prediction is running fine in ChimeraX, just tested a monomer and heterodimer prediction in the ChimeraX release candidate. AlphaFold prediction is not available in the old Chimera software. You would have to give details such as the exact pasted error, the input you were running on, the ChimeraX version, and best to do that with ChimeraX menu Help / Report a Bug.... Tom > On Nov 19, 2022, at 11:38 PM, Kornelius Zeth via Chimera-users <chimera-users(a)cgl.ucsf.edu> wrote: > > Dear all – > > I’m using Alphafold in Chimera and I have a problem to run this properly on Colab. The people from Colab say that the error messages I get since recently are related to Alphafold developers having installed a new version. Could you please let me know what I could do to get the program running again? > > Thanks and have a nice day > > Kornelius > _______________________________________________ > Chimera-users mailing list: Chimera-users(a)cgl.ucsf.edu <mailto:Chimera-users@cgl.ucsf.edu> > Manage subscription: https://www.rbvi.ucsf.edu/mailman/listinfo/chimera-users <https://www.rbvi.ucsf.edu/mailman/listinfo/chimera-users>

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Chimerax Error
by Natalie Loui 20 Nov '22

20 Nov '22

Hi all, I’m trying to visualize a capsid by using the sym command but I keep getting this error ”Assembly "1" not found, have" If you have any advice, please let me know. Natalie Loui PhD Student | Skaggs Graduate School of Chemical and Biological Sciences Email: nloui(a)scripps.edu | Phone #: (808)221-8270 Scripps Research Institute | 130 Scripps Way, Jupiter, FL 33458 | https://education.scripps.edu

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ChimeraX Render by Attribute tool
by Elaine Meng 19 Nov '22

19 Nov '22

Hi Prathvi, There is a different address for ChimeraX questions, chimerax-users(a)cgl.ucsf.edu CC'd here. You can see the currently available tools listed in the ChimeraX User Guide, and links to their pages: <https://rbvi.ucsf.edu/chimerax/docs/user/index.html> <https://www.rbvi.ucsf.edu/chimerax/docs/user/tools/render.html> ... and the dates that they were added in the ChimeraX Change Log <https://www.rbvi.ucsf.edu/trac/ChimeraX/wiki/ChangeLog> ... so yes, we just started adding Render by Attribute to ChimeraX, but you have to get a recent daily build of version 1.6, and it does not have many options yet. Only ChimeraX (not Chimera) has a command to save attributes to a file. In Chimera you have to use the GUI. In ChimeraX we are specifically trying to make commands for all or nearly all actions you can perform with the GUI. I hope this helps, Elaine ----- Elaine C. Meng, Ph.D. UCSF Chimera(X) team Department of Pharmaceutical Chemistry University of California, San Francisco > On Nov 18, 2022, at 4:23 AM, Prathvi Singh via Chimera-users <chimera-users(a)cgl.ucsf.edu> wrote: > > Thanks once again Eric. > I have two more questions. > Is the "Render by Attribute" tool available in chimeraX because I get nothing when I run the command: ui tool show "Render by Attribute". If it isn't available, can I expect it to be added to chimeraX in the future? > Is there a command to save attributes of a residue in chimera (not chimeraX; that you covered in the previous reply) >

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cif writer broken in ChimeraX
by Pranav Shah 18 Nov '22

18 Nov '22

Hi Team, I am trying to save my coords in mmcif format to keep up with the times and I am running into the following error - ///////////////////////////////////////////////////////////////////////////////////////////////////////// AttributeError: 'SaveOptionsWidget' object has no attribute 'compute_sheets' File "/Users/ps/software/ChimeraX_Daily.app/Contents/Library/Frameworks/Python.framework/Versions/3.9/lib/python3.9/site-packages/chimerax/mmcif/gui.py", line 130, in options_string if self.compute_sheets.isChecked(): See log for complete Python traceback ////////////////////////////////////////////////////////////////////////////////////////////////////////// Admittedly I am on a nightly build of the program details of which are - version 1.6.dev202211090831 (2022-11-09) Best, Pranav -- Pranav Shah Postdoctoral Research Fellow. Division of Structural Biology, Wellcome Trust Centre for Human Genetics, University of Oxford, Roosevelt Drive, Oxford OX3 7BN, UK

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Distance between two atoms
by McClean, Phillip 17 Nov '22

17 Nov '22

Hi Everyone, I have a two chain model. I would like to determine the distance between the CD1 atom of residue 77 in chain B and the CD1 atom of residue Leu 150 in chain C. What would be the proper distance command. Thanks for the help again. Phil McClean

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Re: [chimerax-users] [Chimera-users] Finding SASA for individual residues
by Elaine Meng 17 Nov '22

17 Nov '22

On Nov 17, 2022, at 8:01 AM, Prathvi Singh via Chimera-users <chimera-users(a)cgl.ucsf.edu> wrote: > > Hi Elaine, > > The methods you suggested for calculating SASA for residues saved me so much time. Thank you once again for it. > But I have noticed an ambiguity. > When I calculate the SASA for the same residue using chimera and chimeraX, I am getting different values. > For ex: in the PDB file 1TY4, the SASA value for residue 174.a is 2.55 when calculated using chimera and it is 292.44 when calculated using chimeraX. The same is true for other amino acids in other PDB files as well. > Why is there such a difference? > On which of the two software should I rely on? > Also, what is the unit of SASA calculated by these two softwares? > > On Mon, Nov 14, 2022 at 9:42 PM Elaine Meng <meng(a)cgl.ucsf.edu> wrote: > [...] > In Chimera, they are automatically calculated when you show a molecular surface. It creates an attribute named areaSAS, as explained here: > <https://www.rbvi.ucsf.edu/chimera/docs/UsersGuide/representation.html#surfa…> > > See also this previous chimera-user post on using Chimera to get a list of residue SASA values > <http://www.cgl.ucsf.edu/pipermail/chimera-users/2018-June/014729.html> > > (If you use this page <https://www.rbvi.ucsf.edu/chimera/docs/feedback.html> to search chimera-users by "sasa", that was the top hit) > > In ChimeraX, you would use the command "measure sasa" > <https://rbvi.ucsf.edu/chimerax/docs/user/commands/measure.html#sasa> > ... then save attribute "area" to file > <https://rbvi.ucsf.edu/chimerax/docs/user/commands/save.html#attributes> > Hi Prathvi, The atomic coordinates are in angstroms so the surface areas are in angstroms squared. Since this answer is mostly about ChimeraX, I'm also CCing the chimerax-users list. Regarding the differences in value: The programs are both right but based on different surfaces. By default, Chimera encloses all of the protein chains together into one surface (and chain A residue 174 is buried by some interactions with chain C, which you can probably see if you look at the structure). In ChimeraX, the default for display is to make each chain a separate surface, but for SASA calculation, it only depends on what you wrote in the "measure sasa" command. <https://rbvi.ucsf.edu/chimerax/docs/user/commands/measure.html#sasa> As mentioned in my earlier answer, the important part of what you get from "measure sasa" is not (in your case) the total reported in the Log, but instead the "area" attribute value that you will get for each residue. If you just use this ChimeraX command: measure sasa /A:174 ... then it will make a surface that only encloses that one residue, with area 292 as you said. I'm pretty sure that is NOT what you want. Instead you want tthe surface of the whole protein (or maybe one chain) and then the area of the residue given that larger surface. If you wanted to enclose all the protein chains of a model in a single surface (like Chimera default), then measure sasa protein If you wanted to make a separate surface for chain A only, then something like measure sasa /A & protein (the & protein part is still needed so that it won't enclose ligands, water, etc. that also happen to have chain ID A) Using "measure sasa" gives the residue "area" attribute that you could save to file, show in labels, etc. as explained in the help: <https://rbvi.ucsf.edu/chimerax/docs/user/commands/save.html#attributes> <https://rbvi.ucsf.edu/chimerax/docs/user/attributes.html> For your example structure 1TY4, using these ChimeraX commands: measure sasa protein info residues attribute area ...gives 2.55 for residue 174 in chain A, the same as in Chimera. I hope this helps, Elaine ----- Elaine C. Meng, Ph.D. UCSF Chimera(X) team Department of Pharmaceutical Chemistry University of California, San Francisco

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Multiplying the model around the helical cryo-EM map
by Dmitry Semchonok 16 Nov '22

16 Nov '22

Dear colleagues, I am trying to multiply the model subunit into the helical density. I found some command for Chimera sym #1 group c2*h,4.328,23.27,120,1 center 191.99,191.99,191.99 coord #0. Probably I have to somehow find the centre - perhaps with this command, right? Measure center #1 But not for ChimeraX. So my question is, how to do that in ChimeraX? Could you please provide the usage - it would be most helpful. Thanks in advance! Kind regards, Dmitry

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Bond Rotation Questions
by FUNG Chun Po 16 Nov '22

16 Nov '22

Hello I have recently tried to use the bond rotation feature of Chimera X (Windows 10), and I have not been able to get it to work. I have tried the Bond rotation button on the toolbar, and the torsion command to no avail. The bond rotation button does not seem to do anything even when I click and drag with right click. The Torsion command states that my bond “is part of a ring/cycle and cannot be rotated” or “To set torsion, middle two atoms (/A ARG 543 N C) must be bonded;they aren't” I want to ask how do I use this function to rotate upon a simple amide bond. I am not sure am I just selecting the wrong atoms/bonds or is the function just locked for this PDB. The PDB file I am using is 7Y4P and I am trying to rotate about residues 543-544. I have also tried to do it in normal Chimera’s rotation command with no results. Thank you any advice would be welcome. Regards, Chun Po Fung

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