September 2025 - ChimeraX-users - RBVI Mailing Lists

An error opening chimerax seesion
by Yehuda Halfon 11 Mar '26

11 Mar '26

Hi all, I'm using chimeraX 0.8 (2018-12-17) on centos 7 (can't remember the build). Sometimes when I load a session that was saved using this version of chimeraX it gives me this error: Unable to restore session, resetting. Traceback (most recent call last): File "/software/graphics/chimerax/lib/python3.6/site-packages/chimerax/core/ session.py", line 593, in restore obj = sm.restore_snapshot(self, data) File "/software/graphics/chimerax/lib/python3.6/site-packages/chimerax/ std_commands/view.py", line 214, in restore_snapshot for k,v in data ['view attrs'].items(): TypeError: 'NoneType' object is not subscriptable After that I can't open the session again, so I need to remake it. Help, Yehuda Halfon

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VR on ubuntu workstation
by arangarajan＠initialtx.com 04 Mar '26

04 Mar '26

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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ISOLDE and secondary structure restraints
by Guido Hansen 02 Mar '26

02 Mar '26

Hi all, I just started model building in cryoEM maps and get great results using ISOLDE on AlphaFold2-derived initial models. I have a question which is mainly directed to Tristan I guess: Is is possible to use the command line/script to apply secondary structure restraints in ISOLDE? I would like to restrain the initial secondary structure assignment from Alphafold especially at resolution worse than 3.5 A. At the moment I select each and every residue range assigned to helix, parallel or antiparallel beta-strand one after the other and turn on the corresponding restrains in the ISOLDE GUI. Is there a better way via command line of script? Cheers, Guido -- PD Dr. Guido Hansen Group Leader UNIVERSITÄT ZU LÜBECK INSTITUT FÜR BIOCHEMIE Tel +49 451 3101 3122 Fax +49 451 3101 3104 E-Mail hansen(a)biochem.uni-luebeck.de www.biochem.uni-luebeck.de [1] Ratzeburger Allee 160 23562 Lübeck Links: ------ [1] http://www.biochem.uni-luebeck.de

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Volume eraser as cube?
by Oliver Clarke 25 Feb '26

25 Feb '26

Hi all, Hope the chimeraX team & community are having a great start to 2025! There are often situations (in single particle cryo-EM) where I would like to erase using a plane rather than a sphere - e.g., when I want to chop off density protruding from a nanodisc or micelle in order to make a mask. There are various workaround ways to do this (e.g. just making the sphere enormous, making a cubic/rectangular mask and multiplying/substracting, etc), but I was wondering if this is a common enough scenario (perhaps other users can chime in?) that it might be worth adding the option of erasing using a cube rather than a sphere? Cheers Oli

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ChimeraX version 1.9 has been released
by Elaine Meng 23 Jan '26

23 Jan '26

UCSF ChimeraX version 1.9 has been released! ChimeraX includes user documentation and is free for noncommercial use. Download for Windows, Linux, and MacOS from: https://www.rbvi.ucsf.edu/chimerax/download.html Updates since version 1.8 (June 2024) include: - Foldseek search and analysis of large sets of similar structures - Find Cavities tool and "kvfinder" command to identify pockets and channels in macromolecules - optional residue-level summaries of H-bond and contact calculations - "mutationscores" command for analysis and plotting of results from deep mutational scanning - "surface hidefarblobs" command for colocalization analysis of light microscopy channels - raycasting option for medical images or other maps displayed as transparent volumes - selection can be expanded to all residues associated with the same column(s) in a sequence alignment - protein structure metadata can be updated with full chain sequences - missing-structure pseudobonds are labeled with the number of missing residues (default, can be turned off in preferences) For details, please see the ChimeraX change log: https://www.rbvi.ucsf.edu/trac/ChimeraX/wiki/ChangeLog On behalf of the team, 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

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Predicting and modeling post-translationally modified C-terminal endings
by Parks, Ryssa 21 Nov '25

21 Nov '25

Hello, I am trying to predict and model a peptide docking to a receptor protein using ChimeraX's AlphaFold interface, and I was wondering if there is any way to specify post-translational modifications in the AlphaFold input function in ChimeraX? Our peptide has an amidated C-terminus, and my searches online have not yielded much success. Thank you, Ryssa Parks

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Chimera and ChimerX issues after update to MacOS Tahoe
by Rechiche, Othman 14 Oct '25

14 Oct '25

Hi everyone, I recently updated to MacOS Tahoe, Since then I encountered several issues with Chimera, ChmieraX and python. I installed and removed and reinstalled the apps but I still get the same error. For chimera I get this error: [Screenshot 2025-09-24 at 12.08.51 AM.png] FOr ChimeraX, when I try to open a session, it complains that the session was created with another version of python. I opened that session successfully several times before to the update of MacOS and I have never seen this error before. Failed opening file /Users/x/x/x/x/x/x/x/x.pyc: Python code was compiled for a different version of Python Can you please help me fix this? Best Regards, Othman Dr. Othman Rechiche Herbert Irving Comprehensive Cancer Center Columbia University Medical Center Columbia University New York, NY 10032 email: or2296(a)cumc.columbia.edu phone: +1 (814) 880-5554

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Focus in ChimeraX
by Luca Pellegrini 10 Oct '25

10 Oct '25

Hi, What is the ChimeraX equivalent to the Focus command in Chimera? I have selected a portion of a structure, and would like to bring it into focus without dragging it into view. Also Focus would automatically set the selection as the pivot point. Best wishes, Luca Luca Pellegrini, PhD Department of Biochemistry University of Cambridge Cambridge CB2 1GA lp212(a)cam.ac.uk

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Defining pdb chain ontologies
by Pranav Shah 30 Sep '25

30 Sep '25

Hi Team, I am writing to inquire about the functionality of ChimeraX, specifically concerning multi-subunit complexes with multiple chains of a single protein (e.g., PDB 4v7q). I am wondering if there is a feature that allows for manipulating chains by assigning them to functional ontologies. For instance, with the 4v7q example, I would like to be able to execute commands such as: color #1 "vp4" red `mm #1/"vp4" to #2/"vp4" These ontologies could be grabbed from the cif file and if the user decides define their pwn ontologies/groupings. If such a feature does not exist, would you consider exposing such a feature to the user? 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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Orient many tetramers
by Alexandra Zahradnikova 30 Sep '25

30 Sep '25

Hi I have a set of tetramers created by AlphaFold. They are randomly oriented. In order to measure their pore size in a third-party program, I need to orient them with their z axis pointing in the z direction. I can orient them with respect to the screen, but I don't know how to save this view orientation (i.e. so that the z axis in the pdb file goes vertically). Is there any way how to do it? The switch in the "save" command specifying whether to use transformed or untransformed coordinates does not make any difference, and the file is always saved in the original orientation. Best Sasha

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