March 2026 - ChimeraX-users - RBVI Mailing Lists

Tools for clustering conformational ensembles?
by Oliver Clarke 13 Mar '26

13 Mar '26

Hi, Are there any tools in ChimeraX suitable for clustering/analyzing conformational ensembles, e.g. as generated by AFSAMPLE2 (https://www.nature.com/articles/s42003-025-07791-9) or similar approaches? The closest I could find was this: https://www.rbvi.ucsf.edu/chimerax/data/simstruct-doc-oct2024/simstruct.html The similarstructures interface looks great, but it seems like this can only analyze sets of structures generated in the tool - is there any way to use it to analyze an arbitrary set of structures? Basically I would like a way to (for a set of say 200 input structures of the same sequence) quickly align them and then cluster them, to identify and group representative conformational states in the ensemble of predictions. Cheers Oli

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Interface between A and B chain in 4WW1.pdb
by Rosaleen Calvert 11 Mar '26

11 Mar '26

Hi Chimerax interfaces select<help:user/commands/interfaces.html#select> #1/A contacting #1/B [bothSides true][probeRadius 1.4][area Cutoff 3500] Expected a keyword What keyword is required? Have I supplied enough info? Kind Regards Rosy Calvert

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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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Question about scale bar for segmented tomograms
by Choy, Jon 11 Mar '26

11 Mar '26

To whom it may concern: I hope this email finds you well! I am currently working with tomograms and had a question about scale bars and how they are determined. I've looked through the chimearx help dialog and it seems that the scale bar is default set to 100 angstroms, is this true? Does chimerax somehow know to pull from the metadata of the tomogram to determine the scale size? In my case I am working with segmented mrc files and am using the volume setting in the volume viewer to display the rudimentary 3D model. However, I am not sure how to verify that the 100 angstrom scale bar is correct? Any assistance would be greatly appreciated! Best, Jon

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MatchMaps difference map appears split in ChimeraX
by Francisco Murphy Pérez 10 Mar '26

10 Mar '26

Hi, I generated a difference map using MatchMaps ( https://github.com/rs-station/matchmaps) However, when I load the map in ChimeraX, the density appears split into two distinct regions. Interestingly, this does not occur when the same map is opened in Coot, where it displays as expected. I have attached a screenshot for reference. Any ideas on how to “unsplit” the map or what might be causing this behavior? Thanks in advance.

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cxc residue coloring?
by Francisco Murphy Pérez 10 Mar '26

10 Mar '26

Hi Got this cxc script (basically from copy/pasting from the log) ``` open a.pdb open b.pdb open a.mtz structureModel #1 open b.mtz structureModel #2 mm #2.2 to #1.2 bring #2.1,3 show true color byattribute r:seq_rmsd #2.2 target scab palette 0.0237942,#0fc7cf:0.258516,white:0.493237,#9e205e key cyan-white-maroon :0.024 :0.259 :0.493 showTool false select #2.2::seq_rmsd>=0.2 & ::seq_rmsd<=0.5 ``` Everything seems to work, except for the coloring. Am I missing something? Thanks

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clip
by Timothy Springer 10 Mar '26

10 Mar '26

Can you translate this into a clip command I can use in a .cxc file? clip list Using 2 clip planes: near offset -3.0783, axis -0.462,-0.880,0.109, point on plane 218.1,184.5,202.4) far offset 12.676, axis 0.462,0.880,-0.109, point on plane 210.8,170.6,204.1) - Tim *Timothy A. Springer, Ph.D.* Latham Family Professor, Harvard Medical School and Boston Children's Hospital Founder, Institute for Protein Innovation

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ChimeraX Help: Selective residue labeling for peptide/Protein interface !
by Arun Gupta 09 Mar '26

09 Mar '26

Dear ChimeraX Team, I am currently working on visualizing peptide/Protein complexes and I’m having some trouble maintaining specific residue labels while clearing others. My Goal: I want to label: 1. Protein (Chain A) residues that are within 5.0Å of the Peptide (Chain C) residue 1. 2. The Peptide (Chain C) P1 residue itself. 3. I want to ensure residues P2–P9 remain unlabeled. Below is the script I am currently using: set bg white graphics silhouettes t lighting depthCue f size #1 ballScale 0.20 stickRadius 0.2 select /A & (/C:1 :<5.0) show sel style sel ball color byhet view sel label sel text "{0.label_one_letter_code}{0.number}" label @@display residues bgColor white label height 1.0 sel #1/C: 2-9 label delete The issue I am encountering is that when I execute: sel #1/C: 2-9 label delete it deletes not only the labels for peptide residues P2–P9, but also the labels for the protein interface residues that were previously defined and labeled. Question: * Should I be using a more specific selector in the label command itself to avoid using select and label delete sequentially? Any advice on the cleanest syntax to achieve this would be greatly appreciated! Best regards, Arun Arun Gupta PhD, MRSC Sr. Post Doctoral Research Assistant Gillespie/McMichael Group Nuffield Dept. of Clinical Medicine, University of Oxford, Centre for Immuno-Oncology Old Road Campus Research Building, Roosevelt Drive, Oxford OX3 7DQ Tel: + 44 (0)1865 2612913

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Question about changes in alphafold contacts command
by Rowan Cain 09 Mar '26

09 Mar '26

Hello, I am an undergraduate doing research involving protein protein interactions in C. elegans, and I have recently been having some issues with the alphafold contacts command when measuring buried area in protein-protein interfaces. I am running the same batch of dimers that was measured a few years ago with AF2 data, and now with current AF3 data I am seeing vastly different results with the same maxPae, distance values. The main change I noticed with ChimeraX is that the argument in the alphafold contacts command has been changed from “toResidues” to “toAtoms” - is there any reason why this change took place, and would it cause the amount of interacting residues to be measured differently? Thank you, Rowan Cain

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What is the best way to visualize the impact of mutations on the interaction between two proteins?
by jar636＠pitt.edu 06 Mar '26

06 Mar '26

I am working on a project regarding evolution and want to be able to make the necessary mutations on the proteins and then be able to visually see the impact the mutation has on the interaction of the proteins. Specifically, I want to be able to use this information to create a hypothesis as to why these proteins evolved based on the change in interaction. I have tried measuring the distance between the two proteins, but I was wondering what would be the best way to see the biological relevance and overall structural impact of the mutations? Thanks!

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