- ChimeraX-users - RBVI Mailing Lists

Re: Advice on handling cofactor-protein electrostatic interactions
by Boaz Shaanan 08 Aug '23

08 Aug '23

Thanks Elaine, I'll do just that. Cheers, Boaz Boaz Shaanan, Ph.D. Dept. of Life Sciences Ben-Gurion University of the Negev Beer-Sheva 84105 Israel E-mail: bshaanan(a)bgu.ac.il Phone: 972-8-647-2220 Fax: 972-8-647-2992 or 972-8-646-1710 ________________________________ From: Elaine Meng <meng(a)cgl.ucsf.edu> Sent: Tuesday, August 8, 2023 11:57 AM To: �� <bshaanan(a)bgu.ac.il> Cc: ChimeraX Users Help <chimerax-users(a)cgl.ucsf.edu> Subject: Re: [chimerax-users] Advice on handling cofactor-protein electrostatic interactions Hi Boaz, If you use Coulombic it will automatically calculate the charges, as in my example of 1qs0 with the TPP residue. I.e. you don't have to do it in a separate step first, and in fact it may be better if you do not: if you use Add Charge first, it will also add hydrogens and make the surface a lot bumpier. If you just use Coulombic the hydrogens are added only on a temporary copy that is in memory, not on your model, and the coloring will be applied to the smoother molecular surface without hydrogens. You just need to substitute the cofactor residue name for ":tpp" in my example, if it is not TPP. I hope this helps, Elaine ----- Elaine C. Meng, Ph.D. UCSF Chimera(X) team Department of Pharmaceutical Chemistry University of California, San Francisco > On Aug 8, 2023, at 7:09 AM, Boaz Shaanan via ChimeraX-users <chimerax-users(a)cgl.ucsf.edu> wrote: > > Hi Elaine, > > Thanks a lot for the detailed reply and (as always) very helpful suggestions. I'll experiment first with the Chimerax coulombic surfaces and trick to include the cofactor. This sounds attractive, certainly for the TDP case as a starting point. As for derivatives of TDP, which are already included in the pdb, I guess I should follow the 'Add Charges' guide, right? > > Thanks again. > > Boaz > > > Boaz Shaanan, Ph.D. > Dept. of Life Sciences > Ben-Gurion University of the Negev > Beer-Sheva 84105 > Israel > > E-mail: bshaanan(a)bgu.ac.il > Phone: 972-8-647-2220 > Fax: 972-8-647-2992 or 972-8-646-1710 > > > > > From: Elaine Meng <meng(a)cgl.ucsf.edu> > Sent: Monday, August 7, 2023 10:17 PM > To: �� <bshaanan(a)bgu.ac.il> > Cc: chimerax-users(a)cgl.ucsf.edu <chimerax-users(a)cgl.ucsf.edu> > Subject: Re: [chimerax-users] Advice on handling cofactor-protein electrostatic interactions > > Hi Boaz, > This answer addresses coloring by electrostatic potential (ESP). Calculating the electrostatic interaction per se (energy?) is somewhat different and not something that ChimeraX does. > > ChimeraX can color some surface, which could be a molecular surface, by the values in a 3D map, which could be electrostatic potential (ESP). See "color electrostatic" > <https://imsva91-ctp.trendmicro.com:443/wis/clicktime/v1/query?url=https%3a%…> > > The ESP map can come from a Poisson-Boltzmann calculation (APBS, DelPhi, others) or from a more simplistic Coulombic calculation which can be done directly in ChimeraX. > > Poisson-Boltzmann calculations require atomic coordinates, partial charges, and radii, but the different programs differ in how you input these values. > > If I recall correctly, APBS takes as input a pqr file (q means charge, r means radii) which would usually be generated by PDB2PQR, but you said PDB2PQR throws out the nonstandard residues like cofactors, I guess because it doesn't have charges for them. ChimeraX assigns radii and can assign atomic partial charges (via lookup table for standard residues and Antechamber calculation for nonstandard residues like cofactors). However, ChimeraX does not write pqr format. Also in ChimeraX, these partial atomic charges are for all atoms (i.e. all hydrogens explicit) and not a united-atom model (in which hydrogens on carbons are merged with those carbons so that they become implicit) which is often used for Poisson-Boltzmann calculations. So if you wanted to go the APBS route, in ChimeraX you would add hydrogens and charges, then save the cofactor radii and atomic partial charges (atom attributes "radius" and "charge") in the attribute file format, and if you were using a united-atom charge model, manually generate united atoms from CH, CH2, and CH3 groups in the cofactor by adding the hydrogen charges to those of the carbons where they are attached and figuring out the appropriate united-atom radii, then reformat the cofactor atom coordinates, radii and charge values into pqr format and then add these lines to your protein pqr file from PDB2PQR, then use the resulting combined pqr file as input to APBS to get the ESP map that includes cofactor contributions. > > Actually I don't even know if APBS would accept that pqr file or not, but that is what I imagine you would try. So let's assume the APBS calculation will run using that pqr file. > > Then you would open the APBS ESP map that includes cofactor contributions in ChimeraX and color the molecular surface. If the cofactor is covalently attached to the protein then the protein molecular surface may already include it. However, if the cofactor is not covalently attached, you would need to tell ChimeraX specifically to lump it inside of the same surface as the protein with the "include" option of "surface" when you are calculating and displaying the molecular surface. > > The "coulombic" approach wil do more of these steps for you, given the "include" trick as well as the "surfaces" option of the "coulombic" command, but calculating ESP with the relatively simplistic Coulomb's law method. For example, 1qs0 chain A includes a noncovalently bound TPP residue and I could show the surface including the TPP and colored including its potential contribution: > > open 1qs0 > surf include :tpp > coulombic surfaces #1.2 > > <https://imsva91-ctp.trendmicro.com:443/wis/clicktime/v1/query?url=https%3a%…> > <https://imsva91-ctp.trendmicro.com:443/wis/clicktime/v1/query?url=https%3a%…> > > See first image attached with :tpp selected (green outline surface patch) > > If you don't use the "include" and "surfaces" options in these commands, the surface will be redrawn to include only the protein part with the TPP outside of it, like other ligands and the Coulombic ESP will not include the TPP contribution. See second image attached. > > I hope this helps, > Elaine > ----- > Elaine C. Meng, Ph.D. > UCSF Chimera(X) team > Department of Pharmaceutical Chemistry > University of California, San Francisco > > <Screen Shot 2023-08-07 at 7.08.37 PM.png><Screen Shot 2023-08-07 at 7.12.43 PM.png> > > >> On Aug 7, 2023, at 4:10 PM, Boaz Shaanan via ChimeraX-users <chimerax-users(a)cgl.ucsf.edu> wrote: >> >> Hi, >> >> I would like to present effects of mutations around cofactors (TDP derivatives) on the protein - cofactors electrostatic interactions. I use APBS and chimerax to display the electrostatic surface potential of the protein, but since PDB2PQR eliminates the cofactor from the pqr file I need a tool for the cofactor surface potential. I'm wondering what tool I should use for this. Is it Antechamber+chimerax or something else? >> Is there by chance a demo for such scenario? >> I'd appreciate your advice. >> Cheers, >> >> Boaz >> >> >> Boaz Shaanan, Ph.D. >> Dept. of Life Sciences >> Ben-Gurion University of the Negev >> Beer-Sheva 84105 >> Israel >> >> E-mail: bshaanan(a)bgu.ac.il >> Phone: 972-8-647-2220 >> Fax: 972-8-647-2992 or 972-8-646-1710 >> >> >> >> >> _______________________________________________ >> 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://imsva91-ctp.trendmicro.com:443/wis/clicktime/v1/query?url=https%3a%… > > _______________________________________________ > 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://imsva91-ctp.trendmicro.com:443/wis/clicktime/v1/query?url=https%3a%…

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Re: [Chimera-users] Saving phi psi values to a text file
by Elaine Meng 07 Aug '23

07 Aug '23

Hi Prathvi, In Chimera there is no command to save attributes. Instead you have to use the Render by Attribute dialog's File menu as described in the bottom section of this page: <https://www.rbvi.ucsf.edu/chimera/docs/ContributedSoftware/render/render.ht…> In ChimeraX, as far as I know you can only save one attribute to a file at a time with the "save" command. However, it would probably work just to use the "save" command several times and then (outside of ChimeraX) concatenate the multiple files into one file afterward. <https://rbvi.ucsf.edu/chimerax/docs/user/commands/save.html#attributes> Another idea is that in ChimeraX you can list attribute values in the Log with the "info" command, e.g. info residues protein attribute phi So an alternative approach if you don't need the file to be in the attribute-file format is to use "info" multiple times and then save the Log contents to an HTML file with "log save" -- see help pages for those commands: <https://rbvi.ucsf.edu/chimerax/docs/user/commands/info.html#residues> <https://rbvi.ucsf.edu/chimerax/docs/user/commands/log.html#save> I hope this helps, Elaine ----- Elaine C. Meng, Ph.D. UCSF Chimera(X) team Department of Pharmaceutical Chemistry University of California, San Francisco > On Aug 5, 2023, at 10:14 AM, Prathvi Singh via Chimera-users <chimera-users(a)cgl.ucsf.edu> wrote: > > Hi Elaine, > > Is there a command to save the phi and psi angle values of each residue of a PDB file in a text file using UCSF chimera? > > I know we can do this in chimeraX using the command: save C:\myphi.defattr attrName phi format defattr model #1 > > Also, can we use chimeraX to save the phi and psi values in a single file? > > Thanks in advance >

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Query regarding selection
by Prathvi Singh 04 Aug '23

04 Aug '23

Hi Elaine, I want to select all the atoms except the backbone oxygen and nitrogen atom of residues 100.A to 120.A . Is there a command to do this in either chimera or chimeraX? -- Prathvi Singh, Research Fellow, Department of Biological Sciences & Bioengineering, Indian Institute of Technology, Kanpur-208016

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Pseudobonds question
by Aleksei Solomonov 02 Aug '23

02 Aug '23

Dear ChimeraX Developers, I apologize for disturbing you, I have a question, how can I make pseudobonds in ChimeraX similar to Chimera? I mean when I try to create hydrogen bonds, by default, in Chimera (Tools->structure analysis->findHbonds) they appear as lines (or sticks), connected to the structure (left image). But if I export the model and import it in ChimeraX bonds become "disconnected". The same appeared if I place H-bonds directly in ChimeraX (right image). If I select pesudobond, an option of changing its length manually is unavailable. The structure is attached if needed. [cid:image002.png@01D9C590.A8D2F3A0] Thank you in advance! Best regards, Aleksei

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Missing functions for scripting
by Vincent Mallet 28 Jul '23

28 Jul '23

Hello, Thanks a lot for the awesome tool ! I have a question about how to use some commands that are not yet included in the python API : for instance "measure volume". I can run it using a cxc with : */usr/bin/chimerax --script measure.cxc --nogui --exit* Where *measure.cxc *contains looks like : *open test.mrc volume #1 level 0.42 measure volume #1* I don't understand how to do the same with a python script. Is there some way to use chimerax.tools(measure area/volume) to get this tool to work from within a python script ? My use case is that I am running this measurement for different thresholds, and I would like those thresholds to depend on the value of previous thresholds, hence I need looping. For now, I am calling subprocess on the .cxc command above from a python script, but this means that I need to load the mrc every time... Thanks in advance for your help ! Best, Vincent

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Determining Chirality
by steffen＠sthomas.de 27 Jul '23

27 Jul '23

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Download ChimeraX
by songlu 26 Jul '23

26 Jul '23

Dear ChimeraX developers, Thank you for taking the time to read my email. I have a question about downloading ChimeraX and I hope you can help me. When I downloaded the MacOS version of the ChimeraX1.6 on the official website, I found that the download always failed. After trying to switch the browser and the network, it still doesn't work. Perhaps you can help me solve the problem or send me the installation package for the MacOs version of the ChimeraX1.6. I would greatly appreciate it. Looking forward to your reply. Sorry again for the delay in your valuable time. Wishing you a pleasant day. Yours respectfully, Songlu

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transparency for different selection
by Enrico Martinez 26 Jul '23

26 Jul '23

Dear ChimeraX users! I am dealing with the visualization of protein embedded into the plasmatic membrane (composed of water and lipids). Here is my script preset publication 1 rainbow protein palette $palette # for protein surface protein #color protein cornflower blue transparency 95 target s # for lipids surface :OL,PA,PE color :OL coral target s color :PA coral target s color :PE orangered target s hide bonds; hide atoms transparency 55 target s 1) I would like to set different values of the transparency for the surface of lipids and protein. For the moment I found only one possibility to set the transparency for the whole surface indicated above. Would it be possible to selectively apply a transparency command on the particular selection of the system ? 2) how would it be better to visualize the water in the same system in order to maintain the visibility of the protein ? Many thanks in advance Enrico

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How do you refine a structure with a new (or modified) amino acid residue in Isolde
by Trevor Sewell 25 Jul '23

25 Jul '23

Hi Everyone, I am adding residues (essentially modified cysteines ) to the polypeptide chain. e.g. HETATM 1 N2 PGR 0 1.743 -1.624 -0.731 1.00 0.00 N HETATM 2 C1 PGR 0 -0.077 -0.207 -0.018 1.00 0.00 C HETATM 3 C2 PGR 0 1.394 -0.544 0.203 1.00 0.00 C HETATM 4 C3 PGR 0 -0.485 0.927 -0.717 1.00 0.00 C HETATM 5 C4 PGR 0 -1.034 -1.073 0.503 1.00 0.00 C HETATM 6 C5 PGR 0 -1.840 1.189 -0.887 1.00 0.00 C HETATM 7 C6 PGR 0 -2.389 -0.810 0.331 1.00 0.00 C HETATM 8 C7 PGR 0 -2.794 0.323 -0.364 1.00 0.00 C HETATM 9 C8 PGR 0 2.379 0.585 -0.085 1.00 0.00 C HETATM 10 H1 PGR 0 1.529 -0.961 1.213 1.00 0.00 H HETATM 11 H2 PGR 0 0.232 1.599 -1.120 1.00 0.00 H HETATM 12 H3 PGR 0 -0.727 -1.940 1.035 1.00 0.00 H HETATM 13 H4 PGR 0 -2.145 2.053 -1.418 1.00 0.00 H HETATM 14 H5 PGR 0 -3.116 -1.477 0.733 1.00 0.00 H HETATM 15 H6 PGR 0 -3.837 0.527 -0.497 1.00 0.00 H HETATM 16 H7 PGR 0 1.655 -1.298 -1.705 1.00 0.00 H HETATM 17 H8 PGR 0 1.143 -2.449 -0.581 1.00 0.00 H HETATM 18 O18 PGR 0 3.393 0.026 -0.528 1.00 0.00 O HETATM 19 SG PGR 0 2.777 1.511 1.356 1.00 0.00 S HETATM 20 CB PGR 0 1.349 2.524 1.801 1.00 0.00 C HETATM 21 CA PGR 0 1.698 3.446 2.926 1.00 0.00 C HETATM 22 N PGR 0 0.565 4.254 3.182 1.00 0.00 N HETATM 23 C PGR 0 2.646 4.407 2.450 1.00 0.00 C HETATM 24 O24 PGR 0 2.145 5.309 1.717 1.00 0.00 O HETATM 25 O25 PGR 0 3.976 4.409 2.828 1.00 0.00 O HETATM 26 H9 PGR 0 1.980 1.252 -0.806 1.00 0.00 H HETATM 27 H11 PGR 0 1.044 3.140 0.942 1.00 0.00 H HETATM 28 H12 PGR 0 0.527 1.867 2.099 1.00 0.00 H HETATM 29 H13 PGR 0 2.043 2.881 3.803 1.00 0.00 H HETATM 30 H14 PGR 0 -0.245 3.721 3.480 1.00 0.00 H HETATM 31 H15 PGR 0 0.359 4.821 2.336 1.00 0.00 H TER My question is: How do I set up Isolde so that it can refine the structure? Many thanks, Trevor Sewell Disclaimer - University of Cape Town This email is subject to UCT policies and email disclaimer published on our website at http://www.uct.ac.za/main/email-disclaimer or obtainable from +27 21 650 9111. If this email is not related to the business of UCT, it is sent by the sender in an individual capacity. Please report security incidents or abuse via https://csirt.uct.ac.za/report-incident

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Regarding replacing Aspartate with Isoaspartate
by Protya, Satirtha 24 Jul '23

24 Jul '23

Hi Everyone, Hope this email finds you well. I am Satirtha Saha, an undergrad research assistant at UIUC. I am facing a new issue. In one of my peptide PDB file, I need to change the Aspartate Amino Acid with Iso Aspartate Amino Acid. I have been trying to do so, but not sure how to do that. Is there any way or package that can do that? Please let me know. Hope to hear from you soon. Have a great day. -- Yours sincerely Satirtha Saha He/Him/His Beloit College | Class of 2025 Triple Major | Biochemistry, Cognitive Science and Data Analytics Research Assistant | Sweedler Lab | UIUC Admissions Ambassador | Office of Admissions, Beloit College Funding Board Member | Beloit Student Government (BSG) +1(608) 473-6615<tel:+16084736615> Schedule an Appointment<https://admissions.beloit.edu/portal/chat?utm_source=www.beloit.edu&utm_med…> sahass(a)beloit.edu<mailto:sahass@beloit.edu> [Image][Image]

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