January 2024 - ChimeraX-users - RBVI Mailing Lists

Re: Question regarding gaussian filtering
by Tom Goddard 13 Jan '24

13 Jan '24

Hi Dennis, You need to be clearer about what you are trying to achieve "So I guess my question is whether there is a good way to mimick/visualize a lower resolution experimental map using a higher resolution experimental map without considering a sophisticated noise model." If you wanted to mimic a low resolution map for purposes of testing an algorithm (e.g. fitting, segmentation, ...) then the signal to noise at various frequencies would be important. If you just want it to look like a low resolution map to the human eye (why?), well I don't know how much having very different signal-to-noise as a function of frequency will visually alter the appearance. The effects of Gaussian smoothing or simply truncating beyond a certain frequency will create a map that has much higher signal-to-noise then a real low resolution map. You won't see the low resolution noise characteristic of an actual low resolution map. I don't know if that would be visually apparent. Tom > On Jan 10, 2024, at 12:40 AM, Guillaume Gaullier <guillaume.gaullier(a)kemi.uu.se> wrote: > > Hi Dennis, > > A low-pass filter is what you want then: this doesn't dampen signal and noise, simply discards everything past a certain spatial frequency you choose. Just like the low-pass filter applied on-the-fly when using a map as a reference for a 3D refinement or classification job. > I don't know how this can be done in ChimeraX though. > > Guillaume > > From: Dennis Dannecker via ChimeraX-users <chimerax-users(a)cgl.ucsf.edu> > Sent: Wednesday, January 10, 2024 7:15:09 AM > To: Tom Goddard > Cc: chimerax-users(a)cgl.ucsf.edu > Subject: [chimerax-users] Re: Question regarding gaussian filtering > > Hi Tom, > > thank you vey rmuch for the fast and elaborate response. > > I believe I understand it much better now and see why the resolution > per se is not what I am after. > > My intention is to visualize/model the appearance of a lower > resolution map using a higher resolution map. While this should in > principal be possible (the other way around not) but would then > require an appropriate noise model. > > So the gaussian filtering only dampens the amplitudes of the > frequencies in Fourier space. The dampening can be controlled by the > standard deviation of the used gaussian function. The dampening > affects signal and noise equally. > > Does this correspond to a gaussian lowpass filter? Because I was > thinking about removing the high frequencies and setting the cutoff at > different frequencies then corresponding to different "resolutions". > While the resulting map probably has a higher signal-to-noise ratio at > lower frequencies (lower than the cutoff) than an experimental map of > a resolution that this map tries to depict it may still be a good > visual approximation. > > So I guess my question is whether there is a good way to > mimick/visualize a lower resolution experimental map using a higher > resolution experimental map without considering a sophisticated noise > model. > > Thanks again for your help. > > Best > Dennis > > > > Quoting Tom Goddard <goddard(a)sonic.net>: > > > Hi Dennis, > > > > I don't know the answer to your question, but here are some > > thoughts about it. The Gaussian convolution filter just scales the > > Fourier space coefficients by a Gaussian making the higher > > frequencies have lower amplitudes. That is reversible, the high > > frequencies can be scaled back up. So although the real-space > > smoothed map looks lower resolution, it still has the same high > > resolution content. The noise and the signal have both been scaled > > down at high resolutions so the signal-to-noise is just as good at > > those high resolutions. If you did this smoothing on two half-maps > > used to compute the resolution by Fourier shell correlation it would > > still give 2 Angstroms, the smoothing did not change the FSC > > resolution! If you were for example testing a fitting method it > > could easily extract that high resolution information and use it. > > In order to really lower the resolution you would need to add noise > > at high frequencies so the high-frequency signal is lost. > > > > That said you could ask if the noise at high frequencies was not > > scaled down, only the signal, then what would the reduced resolution > > be. We know at the FSC resolution the signal-to-noise ratio is some > > specific value that gives the cutoff correlation. But you would > > need a model of the noise amplitude at other lower frequencies to > > know how attenuating just the signal but not the noise would change > > the resolution. Maybe there is a pretty reliable noise model for > > these cryoEM maps, I'm not sure. > > > > Tom > > > > > >> On Jan 9, 2024, at 2:41 PM, Dennis Dannecker via ChimeraX-users > >> <chimerax-users(a)cgl.ucsf.edu> wrote: > >> > >> > >> Hello, > >> > >> I would like to ask a question regarding the gaussian filtering. > >> > >> I filtered a given map (downloaded from the emdb with the "open" > >> command from chimerax) in chimerax using the following command: > >> > >> vop gaussian #1 sDev X > >> > >> with X taking different values ranging from 0.25 to 20 with different steps. > >> > >> Now I would like to know the resolutions these maps actually > >> correspond to after this gaussian filtering. The originally loaded > >> map is stated to have nominal resolution of 2 Angstroms (GSFSC). > >> sDev defines the standard deviation in Angstrom of the 3D Gaussian > >> function that is used for the filtering. How can one now calculate > >> the resolution these filtered maps correspond to? Is it possible to > >> calculate or state a resolution for these maps that is related to > >> the resolution given for the original map (here 2 Angstroms). > >> > >> Thank you very much. > >> > >> Kind 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 > >> _______________________________________________ > >> ChimeraX-users mailing list -- chimerax-users(a)cgl.ucsf.edu > >> To unsubscribe send an email to chimerax-users-leave(a)cgl.ucsf.edu > >> Archives: > >> https://mail.cgl.ucsf.edu/mailman/archives/list/chimerax-users@cgl.ucsf.edu/ > > > -- > Dennis Dannecker > Master Student of Biochemistry > Department of Chemistry > Faculty of Mathematics and Natural Sciences > University of Cologne > Albertus-Magnus-Platz > 50923 Cologne, Germany > > _______________________________________________ > ChimeraX-users mailing list -- chimerax-users(a)cgl.ucsf.edu <mailto:chimerax-users@cgl.ucsf.edu> > To unsubscribe send an email to chimerax-users-leave(a)cgl.ucsf.edu <mailto:chimerax-users-leave@cgl.ucsf.edu> > Archives: https://mail.cgl.ucsf.edu/mailman/archives/list/chimerax-users@cgl.ucsf.edu/ > > VARNING: Klicka inte på länkar och öppna inte bilagor om du inte känner igen avsändaren och vet att innehållet är säkert. > CAUTION: Do not click on links or open attachments unless you recognise the sender and know the content is safe. > > > > > > > > > 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

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Chimerax background color gradient
by hu.qi＠mayo.edu 12 Jan '24

12 Jan '24

Hello, Is there a way to set a gradient for the Chimerax background color, or use an image? I know Chimerax can do that but not sure how to do it in Chimerax. Any information is appreciated. QH

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Chimerax background color gradient
by hu.qi＠mayo.edu 12 Jan '24

12 Jan '24

Hello, Is there a way to set a gradient for the Chimerax background color, or use an image? I know Chimerax can do that but not sure how to do it in Chimerax. Any information is appreciated. QH

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Re: [Chimera-users] how to play trajectory frames ?
by Elaine Meng 11 Jan '24

11 Jan '24

Hi Mitch, What program are you using? It looks like you may be reading the ChimeraX help, but ChimeraX is a different program than Chimera. If you are using ChimeraX, you may want to ask questions on the chimerax-users(a)cgl.ucsf.edu list and not chimera-users(a)cgl.ucsf.edu ... We try to keep them separate so that people don't get confused. Also if you are actually using ChimeraX, the "coordsets" option of "open" is only for opening PDB or mmCIF files, not XTC. Just leave it out, and simply open both the PSF and XTC with the "coords" option similar to the third example in the ChimeraX help section linked below, except that your trajectory file is XTC and not DCD: <https://rbvi.ucsf.edu/chimerax/docs/user/commands/open.html#traj-options> That just opens the trajectory, it does not play it. To play the trajectory in ChimeraX, you would use the slider GUI and/or the "coordset" command, as mentioned in the help section linked above. I hope this helps, 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 > On Jan 11, 2024, at 3:57 PM, Mitch Murphy via Chimera-users <chimera-users(a)cgl.ucsf.edu> wrote: > > i tried "open 3ft6.psf coordsets true coords 3ft6.xtc" > but i get "'coordsets' has no suffix" error message. > > and with "open 3ft6.psf coords 3ft6.xtc coordsets true" i get "Expected a keyword". > > how do i play frames of a trajectory. i have the psf and xtc or dcd trajectory files available.

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Angular distribution plot in ChimeraX
by Rayees Mattoo 10 Jan '24

10 Jan '24

Hi, I was trying to make an angular distribution plot using .bild file. I want to show the map inside the plot as in the attachment. Few questions: -My map needs to be flipped to get the correct handedness, I think I need to flip the angular distribution plot as well, how to do that? or do I have to go back and get the .bild file for the flipped map? -How can I change the colors and transparency of the angular distribution plot? -Can I get the particle count for each cylinder in the plot? Wanted to show a scale bar for particle distribution around the sphere of the plot. Best Rayees

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Question regarding gaussian filtering
by Dennis Dannecker 09 Jan '24

09 Jan '24

Hello, I would like to ask a question regarding the gaussian filtering. I filtered a given map (downloaded from the emdb with the "open" command from chimerax) in chimerax using the following command: vop gaussian #1 sDev X with X taking different values ranging from 0.25 to 20 with different steps. Now I would like to know the resolutions these maps actually correspond to after this gaussian filtering. The originally loaded map is stated to have nominal resolution of 2 Angstroms (GSFSC). sDev defines the standard deviation in Angstrom of the 3D Gaussian function that is used for the filtering. How can one now calculate the resolution these filtered maps correspond to? Is it possible to calculate or state a resolution for these maps that is related to the resolution given for the original map (here 2 Angstroms). Thank you very much. Kind 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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Question about Cylinder Representation
by Bi, Maxine 09 Jan '24

09 Jan '24

Hi there, I've been stuck trying to make my cylinder representation straight instead of curved as the default. I've tried many commands that I can find in the documentation. Could you please guide me if there is a way to just make the cylinders straight? There is a command like that in Pymol as an example (see link: https://urldefense.proofpoint.com/v2/url?u=https-3A__urldefense.com_v3_-5F-… ). Thank you so much, Maxine

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retrieve the sequence of an atom selection
by Engeholm, Maik 09 Jan '24

09 Jan '24

Hi there, I'm looking for a neat way to retrieve the sequence of an atom selection (in this case part of a double-stranded DNA molecule) from within a python script. I've been playing around with: selection = run (session, 'select #1/A:2-4|#1/B:6-9') for a in selection.atoms.unique_residues: print(a) which gives me: 151 atoms, 169 bonds, 7 residues, 1 model selected /A DG 2 /A DG 3 /A DG 4 /B G 6 /B G 7 /B A 8 /B T 9 This is a good start, but ideally I'd like to get back a contiguous sequence string for each chain (like (('A', 'GGG'), ('B', GGAT'))). Also, I do not really understand, why residue names are reported as 'DG' for strand A, but 'G' for strand B, which makes extracting a sequence string from the above output quite difficult. I've also tried: selection = run (session, 'select #1/A:2-4|#1/B:6-9') for a in selection.atoms.by_chain: print(a[1]) print(a[2].unique_residues.unique_sequences[0][1]) which gives me: 151 atoms, 169 bonds, 7 residues, 1 model selected A AGGGAGTAATCCCCTTG B CAAGGGGATTACTCCCT This is obviously also not what I want since it returns the entire sequence of each chain. I guess I could take the residue numbers from the first command and use those to slice the strings returned by the second, but that feels a little awkward, and so I was wondering if there was a better, more direct way to achieve this seemingly simple task. Your help would be much appreciated. Cheers, Maik

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ChimeraX : Cannot recommend to my class until minimization with vital cofactors such as FAD, NADH is built in. Returning to Chimera.
by Anne-Frances Miller 09 Jan '24

09 Jan '24

Dear Sir or Madam, After devoting several days to updating three weeks of my course to use ChimeraX instead of Chimera, I am returning to Chimera. ChimeraX may be a great cutting-edge tool, but it is not ready for a wider audience until it can make ‘common’ tasks easy. Please do not distance research from science. We desperately need science to be exciting and accessible to a wide audience. Chimera does that. ChimeraX does the opposite, sending the clear message that only an elite few are deemed worthy. Please please please, open the door to wider use, for the sake of science, and for the sake of the citizens of our country (who fund your agencies via taxes). Very Helpful - To make images with transparent backgrounds, members of my class as not going to type out ’transparentbackground true’ (even my emailer wants to spell the first string as two words). CRUCIAL - in-program minimization that includes critical cofactors (present in >40% of all enzymes and the actual source of their activities often!!) FAD, FMN, NAD(H), how is this anything more than structural biology if the sources of activity are not included? (‘biology’ implies life. Life REQUIRES chemical reactivity.) CRUCIAL - in-program trajectory analysis that can tabulate (for example) a distance, frame-by-frame and allow export in tabular form. Very Helpful - worms with thicknesses that can represent an attribute. These provide a critical orthogonal way to add a second attribute when color is already in use for a first. Very Helpful - Lighting/effects/side view GUI that allows easy optimization of figure reflectivity, special effects, all in one place and does not require users to remember what Cartesian coordinates they gave their first light. It is so much faster and delivers much better results than ChimeraX. This email records the current worst applicability gaps only, I see others have reported more. I would like to like ChimeraX, but as a person trying to bring science to wide audiences, ChimeraX is the best argument for Pymol I have seen in a while. Do not stop supporting Chimera until ChimeraX can serve real humans, please! Sincerely, and thanks to the team, Anne-Frances Novel Meritorious Research (and teaching) —•—•—•—•—•—•—•—•—•—•—•—•—•— A.-F. Miller, Ph. D. (she/elle/sie) University Research Professor Professor of Chemistry University of Kentucky https://www.uky.edu/~afm/ Visiting Fellow, Einstein Foundation of Berlin

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Depth cueing
by Paul Miller 09 Jan '24

09 Jan '24

Hi How do I depth cue in ChimeraX? In Chimera I used to be able to precisely control this from the side view window but I cannot find any way of controlling depth cueing in ChimeraX. Thank you. Cheers, Paul Paul Miller (he/him), PhD University Lecturer in Pharmacology Department of Pharmacology University of Cambridge Tennis Court Road Cambridge CB2 1PD +44 1223 761267 https://www.phar.cam.ac.uk/research/miller

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