February 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

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

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

4 3

Determining Chirality
by steffen＠sthomas.de 20 Jun '25

20 Jun '25

4 5

What is the .exe file for ChimeraX Toolbox?
by m.i.bashir＠bham.ac.uk 11 Mar '25

11 Mar '25

Hi all, First time posting here. I'm looking to find the name and location of the file/folder that manages the ChimeraX in-app browser. The way I launch the browser is to go to 'tools' in the top bar, then press 'more tools', and then it brings up the ChimeraX Toolshed Where is the .exe file that controls this in app browser? I am attempting to find the .exe file and black list it, so we can use ChimeraX for an exam Thanks,

4 3

define integer attributes for multiple individual pseudobonds
by hannes.ludewig＠googlemail.com 28 Feb '25

28 Feb '25

Dear developers, I am trying to color pseudobonds by an individual (per-bond) attribute value (integer). I seem to be unable to use .pb files to create individual pseudobonds. And when I am using the pbond command several times providing an individual name for each pseudobond thus creating individual models (#1.1, #1.2, etc) I am unable to assign an attribute and color all pseudobonds according to the corresponding attribute value. What I want to create is similar to the alphafold contacts colored by PAE. Only that the values I am providing aren't PAE and I would like to determine the residue pairs that form each pseudobond. I apologize in case I am overlooking something obvious, but your help and/or clarification would be very much appreciated. Thank you. Best wishes, Hannes

3 2

Disulphide bridges in ISOLDE
by Guillaume Gaullier 28 Feb '25

28 Feb '25

Hello ISOLDE users and Tristan, Is there a distance threshold at which ISOLDE won't let me close a disulphide bridge? I am puzzled, because it seems I can close a disulphide between two Cys about 10 residues apart in sequence and quite far from each other in space. In fact much further apart than a bond length, so the resulting bond looks ridiculously stretched. But it is quickly fixed when running a local simulation, even if it needs to pull the backbone out of density to achieve a reasonable S-S bond length. In the same model, I have two other Cys that follow each other in sequence. When loading the AlphaFold prediction, the two S atoms are close enough (for some reason) that ISOLDE offers to make the disulphide, so I say yes. Later on, wanting to test both options to assess which one is best supported by the map, I can break this disulphide, but once I do there is no way to close it again. In this case, the two S atoms settle about 3.4 Å apart when removing the bond, which is longer than an ideal disulphide, but much shorter than the distance over which ISOLDE still allowed me to form a disulphide in the first case. The documentation doesn't say anything about disulphides (or somehow I missed it). In fact, there seems to be no command to operate on disulphides? Using the menu item does not write anything to the Log, so if there is a command I cannot find what it is and what options it might accept. If someone can help with this, I would appreciate it! Thank you, Guillaume --- Guillaume Gaullier, PhD Researcher, Blikstad group Molecular Biomimetics / Microbial Chemistry Department of Chemistry - Ångström Uppsala University Lägerhyddsvägen 1 752 37 Uppsala Sweden När du har kontakt med oss på Uppsala universitet med e-post så innebär det att vi behandlar dina personuppgifter. För att läsa mer om hur vi gör det kan du läsa här: http://www.uu.se/om-uu/dataskydd-personuppgifter/ E-mailing Uppsala University means that we will process your personal data. For more information on how this is performed, please read here: http://www.uu.se/en/about-uu/data-protection-policy

3 6

Assistance Required: Extracting List of Interacting Residues within 4 Å in UCSF Chimera
by Rashmi Aggarwal 27 Feb '25

27 Feb '25

Dear UCSF Chimera Support Team, I hope this message finds you well. I am currently working on analyzing interactions between two molecular structures using UCSF Chimera. I have successfully identified residues that are within a 4 Å distance between the two molecules. However, I am encountering difficulties in obtaining a clear, textual list of these interacting residues, as reading them directly from the visual representation is challenging. Could you please provide guidance on the specific commands or procedures within Chimera that would allow me to: 1. *Select residues* in one molecule that are within 4 Å of the other molecule. 2. *Generate and export a list* of these selected residues for further analysis. I have attempted various selection and reporting commands but have not yet achieved the desired outcome. Detailed instructions or references to relevant documentation would be greatly appreciated. Thank you very much for your assistance. Best regards, Rashmi

2 2