February 2024 - ChimeraX-users - RBVI Mailing Lists

Save PDB relative to map - does not store relative postion
by Dennis Dannecker 02 Feb '24

02 Feb '24

Hello, I am running into an issue with saving pdb coordinates and their relative postioning. I am fitting an atomic model into a map model, explicitly the atomic model is rotated and translated into the map using fitmap (local optimization, rigid body fitting). Once the fit is complete, the atomic model is saved as a PDB file with the checkmark set on "Save relative to model...", here I have chosen the map the atomic model has just been fit to. This is, I think, in accordance with what is adviced in the doc of the "Fit in Map" Tool. However, when I reopen said atomic model and map in a new chimerax session (loading the map and loading the pdb file just saved relative to this map), none of the rotational and translational information is kept and the map and atomic model are in no meaning full spatial relationship. I wanted to use this procedure to prepare for cryofit and/or real space refinement in phenix, so I would like to use map and pdb for another software. As is mentioned in the doc of the "Fit in Map" Tool, volume files generally do not store rotation, thus the pdb file should be chosen to capture the rotational and translation information. Am I understanding something wrongly here or how come that the postioning is completely off when I reload map and model? Thank you for your help. Best regards, Dennis --------------------------------------------- Dennis Dannecker Master Student of Biochemistry Department of Chemistry Faculty of Mathematics and Natural Sciences University of Cologne Albertus-Magnus-Platz 50923 Cologne, Germany

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Display volume default threshold level
by Chenwei Zhang 02 Feb '24

02 Feb '24

Dear UCSF ChimeraX developers, I am Chenwei Zhang, a PhD student from UBC, Canada. I am currently using ChimeraX for cryoEM density map visualization, which did a really nice job. There's one question I would like to seek answers from you. When I show a density map in ChimeraX GUI, it show automatically show a threshold level. Here's a quick example when I open emd_6272.map file: _Opened emd_6272.map as #1, grid size 108,108,108, pixel 1.02, shown at level 0.0555, step 1, values float32_ May I ask how does ChimeraX get this threshold? Or more generally, how does ChimeraX calculate the density values to get this final threshold value? Is there any command I could use in ChimeraX to extract this value? I tried to find answers in your documentation but failed so I am writing this email for help. Thank you in advance and look forward to your reply. Best, Chenwei

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Using GPU in chimerax
by Sharif, Omar 01 Feb '24

01 Feb '24

Hello, I am using Chimerax with a tool called DeepSSETracer, a model that performs segmentation on the secondary structure of 3d cryo density maps. I need GPUs and CUDA enabled to test the tool. When I run the model, I have a message in the log that says Cuda is not available although I am running on a machine where relevant Nvidia GPU drivers and Cuda are already installed and working properly. I am attaching the screenshot [cid:d821ceae-9b2c-4a88-a7ba-c45b2935bee2] Is there any way to enable GPU usage within the ChimeraX? Is there any way to check if ChimeraX is using GPU and CUDA? I will be waiting for your reply. Thanks in advance, Omar Omar Sharif Ph.D. student Department of Computer Science Old Dominion University Email: osharif(a)cs.odu.edu https://odu.zoom.us/my/omarsharif786

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Center atom
by Cygler, Miroslaw 31 Jan '24

31 Jan '24

Hi, I just started using ChimeraX and am confronted with how to do a simple task, namely, to placer a specific atom at the centre of the screen. What is the replacement for the command “centre” in Chimera? Thanks, Mirek

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ChimeraX-users February 2024