October 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

4 6

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

3 6

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

6 9

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

3 2

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

3 4

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

4 9

ChimeraX VR (specifically LookSee)
by jrj.healey＠gmail.com 02 Nov '25

02 Nov '25

Hi all, I'm trying to get ChimeraX VR standalone working on a Quest 3. Trying to follow the instruction online, but I fall at pretty much the first hurdle trying to subscribe to the release candidate channel on Meta AppLab - I get an error saying the channel is out of date or can no longer be found (or something to that effect). Do you have any more information on this, and does this mean side-loading is my only option potentially? Thanks Joe

3 2

Further help
by Emily Cioppa 29 Oct '25

29 Oct '25

Good evening, In addition to my previous question, I am also having difficulty appending chains. If I import molecular models into Chimera/ChimeraX that each have individual model names and singular Chain IDs, is there a way to combine these into a singular model and renumber the residues as one continuous sequence throughout the combined model? For example, I have three molecular models that are each components of a single RNA molecule, and each have their own pdb file and a singular Chain ID. I know how to physically orient all of them spatially and renumber the residues of each such that when hovering over the molecular model moving from 5’ to 3’ the sequence numbering is continuous and correct across all chains. However, even when I combine the three individual models into one at the beginning and change the chain IDs of all three to be the same ID at the end, when I view the combination model in sequence viewer, it has just appended all three chains together with no regard to residue order. Since each of the three models is a chunk of double helix, I would need the numbering to be in 5’ to 3’ order throughout the entire combination model sequence viewer, in the way that I have renumbered it and in the way that it is in the visible combined model/structure. Thank you for your help.

2 1

Help with Chain ID commands
by Emily Cioppa 29 Oct '25

29 Oct '25

Good evening, I have a quick question regarding the changechains command in Chimera/ChimeraX. If I have a single model open that inherently has one single chain, is there a way to select a continuous strand of residues in the sequence and change the Chain ID of only the selected residues to something else? It seemed from my online research that this is possible, however, I cannot get it to work. Any advice would be appreciated as soon as possible. Thank you. Best, Emily Cioppa Research Assistant The Rockefeller University

2 1

Average attribute
by Reza Khayat 29 Oct '25

29 Oct '25

Hi, How do I average atom attributes to residue attributes? Let's assume the attributes name is mapvalues. Thanks. Best wishes, Reza Reza Khayat, PhD City College of New York Department of Chemistry and Biochemistry

3 3