- ChimeraX-users - RBVI Mailing Lists

RMSD for all frames in a trajectory
by Alexandra Zahradnikova 01 May '25

01 May '25

Dear All, I am working with a trajectory of a tetramer. I would like to align the A chains in all frame of the trajectory and then calculate the rmsd of all chains in all frames relative to the respective chain of the first frame (i.e., align only chains A but calculate for all chains), and write the results to a text file. Is that possible? I can do a similar calculation with a script in old Chimera but don’t know how to do it in ChimeraX. I attach the zipped script for old Chimera. Best regards Sasha

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Morphing of structures with different chain numbers
by Enrico Martinez 01 May '25

01 May '25

Dear ChimeraX Users, I am trying to perform a morphing between two cryo-EM structures of the same complex, where one structure has twice the number of chains as the other (PDBs 3J9K and 8Y6Q). However, the larger structure causes an error during morphing. I have attempted to write a script that aligns the two structures and deletes the unmatched chains from the larger structure. Unfortunately, the script is not working as expected. from chimerax.core.commands import run def delete_unmatched_chains(session): # Get models #1 and #2 m1 = next((m for m in session.models if m.id == (1,)), None) m2 = next((m for m in session.models if m.id == (2,)), None) if m1 is None or m2 is None: session.logger.info("Model #1 or #2 not found.") return chains1 = {chain.chain_id for chain in m1.chains} chains2 = {chain.chain_id for chain in m2.chains} unmatched = chains1 - chains2 if unmatched: chain_ids = ",".join(unmatched) # Deleting unmatched chains run(session, f"delete /{chain_ids}") session.logger.info(f"Deleted chains: {', '.join(unmatched)}") else: session.logger.info("No unmatched chains found.") Could you please help me or alternatively propose another solution? Any suggestions would be greatly appreciated. Thank you in advance ! Enrico

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Saving Images with Specific Dimensions and DPI in ChimeraX
by svle＠tiscali.it 30 Apr '25

30 Apr '25

Hi, In Chimera, when saving an image, it's possible to specify the output size in centimeters and the resolution in DPI. This feature is very useful for preparing figures for theses and publications. Is it possible to do the same in ChimeraX? I've read the documentation for the save command, but it's not entirely clear to me how to achieve this. Do you have any suggestions? Best regards, Saverio

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Reproducing the Chimera Preset Publication 5 ( flat ribbon ) in ChimeraX
by svle＠tiscali.it 29 Apr '25

29 Apr '25

Hi, it is possible to reproduce the Chimera Preset Publication 5 ( flat ribbon ) in ChimeraX? What are the commands to use in order to have this type of preset in ChimeraX? This is a very nice preset. Thanks. Saverio

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How can I overlay the 2Fo-Fc density map onto the amino acid residues I specified?
by 1025049892＠qq.com 29 Apr '25

29 Apr '25

Every time I open the map file in ChimeraX, I find that it doesn't overlap with my PDB structure. Why is this the case, and how can I make them match? Thank you for your attention. I'm looking forward to your reply.

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How to apply symmetry I to generate an icosahedron model
by 唐延婷 29 Apr '25

29 Apr '25

Hi doctor, when I open a map (ID 1) and a model (ID 2), the map is the whole icosahedron while the model is the protomer of the icosahedron. I want to apply symmetry I to generate an icosahedron model. I have rotated and translated the model into a reasonable position inside the map and then done a “fit in map” to get the initial placement for sym. Then I enter a command ''measure center #1''，center of mass xyz coordinates for map_sharp.mrc = (238.08, 238.08, 238.08)，enter another command ''sym #2 I,222 center 238.08, 238.08, 238.08'' I can see an icosahedron model fit in map. But when I save the icosahedron model.pdb, I found the icosahedron model actually is the model of the protomer. How can I apply symmetry I to generate a true icosahedron model, used for subsequent model refine in coot and real_space_refine in Phenix. Thank you very much. Best wishes! yanting 延婷 yanting.tang(a)mail.nankai.edu.cn

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Issues with find cavities tool
by Marino, Claudia 28 Apr '25

28 Apr '25

Greetings, I am not sure why I recently cannot longer use the tool “find cavities”. My ChimeraX version is 1.9 and my MacOS is Sequoia 15.4. Please, find below the screenshot of the Error message. [cid:image001.png@01DBA7F0.57B85750] Thank you very much in advance for your help. Sincerely, Claudia.

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reduce gridpoints on the cryoEM map (640 x 640 x 640 ) to ( 320 x 320 x 320)
by arangarajan＠initialtx.com 28 Apr '25

28 Apr '25

hi, i need to reduce the grid points to make the map work with MOE. I am not sure if this is possible in chimerax and i would appreciate some suggestions for creating a mrc file with reduced grid points. please let me know your thoughts. best amith

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VR on ubuntu workstation
by arangarajan＠initialtx.com 24 Apr '25

24 Apr '25

Hi, i got steam VR installed but later found out that Oculus does not support linux. Is there a work around for using chimerax VR on latest ubuntu machine with oculus rift s headset? i can get other headset also if it will fit this purpose. thanks in advance, best amith

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Labeling chains in MD simulation trajectories of a multimer
by Alexandra Zahradnikova 24 Apr '25

24 Apr '25

Hi All, I am interested in MD simulations of homomultimeric ion channels, which I do in GROMACS. I would like to analyze my output files with ChimeraX but I run into the following problem: The .gro output of the simulation consists of a single chain named /? in ChimeraX. When I open the file in old Chimera, it shows every chain of the original protein separately but with the same name ()

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Effect of clearing ChimeraX cache from Mac?
by Radford, Katelyn M. (Kate) 23 Apr '25

23 Apr '25

Hi there! I'm in the throes of a memory-expensive project and my computer is running out of space. A little bit of googling led me to conclude that it would probably make sense for me to clear my system's cache, as my system files take up about a third of my disk space. ChimeraX cache files account for a substantial portion of that memory usage. As I make figures, I save .cxs files of each figure so that it's easy to go back and edit things that need to be changed. My ChimeraX also has a bunch of plug-ins installed (e.g. ISOLDE). I'm wondering: how much damage will I do to my installation and to my .cxs files if I delete the ChimeraX cache? System and software details: ChimeraX version: 1.9 MacOS: Ventura 13.0 Chip: Apple M2 Max Thank you all so much for the excellent work you do, Best wishes, Kate Kate Radford (she/they) PhD candidate, Biochemistry and Molecular Biophysics California Institute of Technology 1200 E California Blvd Pasadena, CA 91125

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Re: cartoon not displaying in ChimeraX despite complete backbone
by amith ranga 22 Apr '25

22 Apr '25

Dear ChimeraX users, I'm unable to display the cartoon representation for pdb file in ChimeraX, even though the residues and atoms appear complete. The structure contains standard RNA residues (A, G, U) , Each residue includes all expected backbone atoms (P, O5', C5', C4', C3', O3', C1', O4', etc.) as well as complete base atoms and hydrogens. The file was written out from MOE software and I am not sure if this is an issue. Some tips on how to edit the pdb file would be helpful Thanks, amith

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[ISOLDE] Handling Lys-Asp iso-peptide bonds and D-amino acids
by Yang Lee 22 Apr '25

22 Apr '25

Addressing this to Tristan, in all likelihood. Is there a way of parameterising KD isopeptide bonds and D-amino acids? Perhaps a secret three letter code I can rename the residues to make them play nice? Unfortunately, I'm trying to model a peptide that has both of these exotic elements. Cheers, Yang

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Color of unrolled density maps
by Sen, Anindito 21 Apr '25

21 Apr '25

Dear ChimeraX Team, Is there a way we can keep/restore the color of the unrolled helical density maps ? Regards Anindito Sen. Ph.D Microscopy and Imaging Center Texas A&M University 301 Old Main Dr College Station, TX 77843-2257 Office: ILSB Room 1133 <http://microscopy.tamu.edu/>Tel. 979-458-9881 fax: 979-847-8933 http://microscopy.tamu.edu<http://microscopy.tamu.edu/>

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Re: Regarding peptide bond formation using chimeraX
by Tom Goddard 21 Apr '25

21 Apr '25

Hi Harpreet, I'm not sure how you deleted the bond. If you deleted a peptide bond with delete bonds /A:102@C /A:103@N or the equivalent menu Actions / Atoms and Bonds / delete then you could just recreate it with bond /A:102@C /A:103@N I'm not sure why you would do that since there is no need to delete a bond to move the two pieces of the structure. Instead maybe you split the protein into two separate models. In that case you can't simply add a bond between different models, instead you have to combine the models (e.g. command "combine #1,2"). You might get better answers on the ChimeraX mailing list, so I have CC'ed that list. Tom > On Apr 21, 2025, at 4:06 PM, Singh, Harpreet <harpreet.singh2(a)ucsf.edu> wrote: > > Dear Professor Goddard, > > I hope you are doing well. > > I am a Postdoctoral scholar from the Robert M. Stroud lab. I recently deleted a peptide bond from our protein structure to adjust the model for cryo-electron microscopy (cryo-EM) mapping. I am now attempting to reconstruct the peptide bond using the Build Structure tool. However, I am encountering an error message indicating that there are no chain-terminal carbons in the atoms. > > I would appreciate your assistance in resolving this issue. > > Thank you for your time and consideration. > > Best regards, > Harpreet Singh > Postdoctoral Fellow, Stroud lab > Department of Biochemistry and Biophysics > UCSF

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Color of unrolled density maps
by Eric Pettersen 21 Apr '25

21 Apr '25

The original was sent to the wrong address (chimerax-users-bounces)… Dear ChimeraX Team, Is there a way we can keep/restore the color of the unrolled helical density maps ? Regards Anindito Sen. Ph.D Microscopy and Imaging Center Texas A&M University 301 Old Main Dr College Station, TX 77843-2257 Office: ILSB Room 1133 <http://microscopy.tamu.edu/>Tel. 979-458-9881 fax: 979-847-8933 http://microscopy.tamu.edu <http://microscopy.tamu.edu/>

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Quality of sphere representation
by Enrico Martinez 21 Apr '25

21 Apr '25

Dear ChimeraX users! I wonder if there is a special option which would allow me to increase the quality of sphere representation (which are displayed by default for big cryo-em protein complexes loaded in chimeraX) in the same way as it can be done for surfaces using gridSpacing ? Many thanks in advance Enrico

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Concatenating trajectories in ChimeraX
by Alexandra Zahradnikova 20 Apr '25

20 Apr '25

Dear All, I am new in molecular simulation and not very much experienced with ChimeraX. I did not find an easy way to concatenate trajectories (in my case, .xtc files from gromacs). Any suggestions would be welcome. Thanks in advance Sasha ________________________________________________________________________ Alexandra Zahradníková, PhD Department of Cell Cardiology Institute of Experimental Endocrinology Biomedical Research Centre SAS Dúbravská cesta 9 845 05 Bratislava Slovakia Mobile: +421 908 069 796

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seeking help
by 张可依 20 Apr '25

20 Apr '25

Dear chimerax, hello, I would like to know if chimerax can draw protein secondary structure topology maps, and if so, can you tell me how to do the drawing?Something like the picture below Your help is of great importance to me and I, with my most sincere hope, look forward to your reply. All the best keyi [cid:494273c0-4f59-4f19-bd4d-5ac989d92136]

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Question about morphing trajectory
by Enrico Martinez 20 Apr '25

20 Apr '25

Dear ChimeraX users ! Using the following command, I generated a 200-frame trajectory that morphs through three selected conformations: morph #2,3,4 core 0.1 frames 200 wrap f rate linear Would it be possible to have the morphing trajectory end on the starting structure (so the full transition path ends on the first snapshot in the morphin trajectory), so that I can create a smoothly looped GIF animation? Many thanks in advance ! Enrico

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Combine PDBs in models instead of changing chainId ?
by Vincent CHAPTAL 17 Apr '25

17 Apr '25

Hi, using "combine #1-3" with 3 models having chain A only, it changes the chain Id to B and C for models #2-3, as described in the doc. Is it possible to combine PDBs as a multimodel PDB, seperated by MODEL keywords in the PDB file? Thank you. Vincent -- Vincent Chaptal, PhD Director of GdR APPICOM Drug Resistance and Membrane Proteins Lab MMSB -UMR5086 7 passage du Vercors 69007 LYON FRANCE +33 4 37 65 29 01 http://www.appicom.cnrs.fr http://mmsb.cnrs.fr/en/

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Request for Academic Use Confirmation Document – ChimeraX Demonstration Class
by Coordenação Farmácia_ 17 Apr '25

17 Apr '25

Dear UCSF ChimeraX Team, My name is Emanuell Santos, I am a pharmacist, Ph.D. in Drug Development Technology, and the coordinator of the Pharmacy program at a private Brazilian college. I also teach Medicinal Chemistry for both Pharmacy and Medical students. I am reaching out to respectfully request your support in including UCSF ChimeraX in a practical session of my Medicinal Chemistry course. The goal is to introduce students to molecular modeling approaches through a demonstrative class where they can also explore some of the software’s functionalities directly. This initiative is aligned with national educational guidelines from our Ministry of Education, which emphasize the inclusion of innovative and technological methodologies in undergraduate teaching. I plan to use the free academic version of ChimeraX solely for educational purposes and without any commercial intent. I kindly ask whether it would be possible to obtain a brief statement or document from UCSF (even if generic) confirming that such use falls within the allowed academic scope. This would be helpful in documenting compliance with institutional and governmental regulations. I greatly appreciate your attention and support, and I look forward to your response. Warm regards, Emanuell Santos Coordinator – Pharmacy Program FACENE/RN -- Prof. Dr. Emanuell dos Santos Silva *Coordenação de Farmácia - FACENE/RN* Por favor, confirmar o recebimento deste e-mail.

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Re: Unable to display GLY in Chimera
by Elaine Meng 15 Apr '25

15 Apr '25

Hello Qiang, I guess you are talking about ChimeraX, not Chimera. They are two different programs. You can just hide all the other glycine atoms. This is not a bug. The suppressBackboneDisplay *allows* you to show both cartoon and backbone atoms at the same time, but you can still hide all the atoms you don't want to show. cartoon suppress false hide :gly show :93 I hope this helps, Elaine ----- Elaine C. Meng, Ph.D. UCSF Chimera(X) team Resource for Biocomputing, Visualization, and Informatics Department of Pharmaceutical Chemistry University of California, San Francisco > On Apr 15, 2025, at 9:16 AM, Qiang Liu <liu01301(a)umn.edu> wrote: > > Hi Chimera > > I am a Chimera user and unable to display single GLY as stick and cartoon. I found commend "suppressBackboneDisplay", however this command makes all the GLYs displayed as stick and cartoon. I only want to display GLY93 as stick and cartoon and could you please let me know how to make it happen? Thank you. > > Qiang. > > -- > Qiang Liu, Aldrich Lab > Medicinal Chemistry, College of Pharmacy > University of Minnesota > > 8-115 Weaver-Densford Hall > 308 Harvard St SE > Minneapolis, MN 55455

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How to save the PAE plot as an image in ChimeraX using command line ?
by picasa1983＠gmail.com 14 Apr '25

14 Apr '25

Hi, I am using ChimeraX to visualize AlphaFold models and display the PAE plot with: alphafold pae #1 /path/to/confidences.json I would like to save only the PAE plot (not the 3D structure view) as a .png or .pdf file. What is the correct command to save the PAE plot image in ChimeraX? Thanks a lot!

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B-strand arrowheads
by Lee Bardwell 13 Apr '25

13 Apr '25

Hi Elaine and team, I’ve noticed an issue that sometimes happens when I change some residues to a beta strand, e.g. setattr /A:149-151 res ss_type 1. Sometimes an arrowhead is not placed at the end of the strand. Am I doing something wrong? Or is there a way to force an arrowhead? Thank you! _________________________________ Lee Bardwell, Ph.D. Professor and Vice-Chair, Dept. of Developmental & Cell Biology Charlie Dunlop School of Biological Sciences University of California, Irvine __________________________________

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