- Chimera-users - RBVI Mailing Lists

Re: [Chimera-users] a question relate to Chimera
by Elaine Meng 26 Aug '15

26 Aug '15

On Aug 25, 2015, at 6:16 PM, Smith Liu <smith_liu123(a)163.com> wrote: > Dear Elaine, > Here there is a sentence "a particle has a diameter of 100 pixels and the width of the reconstruction box is 256 pixels". Will you please tell me by Chimera how can I know the diameter of the particle and the width of the reconstruction box, as described in the cited sentence? > > I am looking forward to getting a reply from you. > Best regards. > Smith Dear Smith, It is recommended to send Chimera questions to chimera-users(a)cgl.ucsf.edu (CC’d here) instead of to me directly. I don’t know where that sentence came from, so I’m not even sure it is a Chimera question. By “pixels” maybe the authors mean grid units. They probably just knew this about their own data without trying to get it from Chimera, but at least for the width of the box, you can see the grid dimensions just to the right of the dataset name in the Volume Viewer dialog. <http://www.rbvi.ucsf.edu/chimera/docs/ContributedSoftware/volumeviewer/fram…> Best, Elaine ----- Elaine C. Meng, Ph.D. UCSF Computer Graphics Lab (Chimera team) and Babbitt Lab Department of Pharmaceutical Chemistry University of California, San Francisco

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on point-group symmetry used for the 3-D calculation
by Smith Liu 25 Aug '15

25 Aug '15

Dear All, By chimera, can we know the point-group symmetry used for the 3-D calculation? Best regards. Smith

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on voxel size measured in angstroms
by Smith Liu 25 Aug '15

25 Aug '15

Dear All, Will you please tell me by Chimera how can we know the voxel size measured in angstroms? Smith

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is the connection present?
by Dmitry 25 Aug '15

25 Aug '15

Dear Colleagues, I have 3d tetramer volume density where I fitted known x-ray structure of monomer (to each unit of tetramer). I want to check the inter-monomeric space, whether there is connections between 2 monomers. Is there a command or script that checks the presence of contacts between bounds of 2 structures? Thank you Sincerely, Dmitry

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Electrostatic Potential Visualization
by Chun, Minju 25 Aug '15

25 Aug '15

Hello, I am an intern working with Chimera, and I was wondering if I was missing a plug-in that calculated electrostatic potential. I attempted to load a dx and cube file to emulate electrostatic potential, but there seemed to be a problem finding/reading the files(perhaps I'm doing this wrong too). I thought that if I calculated electrostatic potential directly with Chimera, I could see electrostatic potential. It says on your website that Chimera can calculate the electrostatic potential with APBS: "electrostatic potential calculated with Adaptive Poisson-Boltzmann Solver<http://www.poissonboltzmann.org/apbs/> (APBS); the APBS<http://www.cgl.ucsf.edu/chimera/docs/ContributedSoftware/apbs/apbs.html> tool in Chimera runs this program via web service provided by the NBCR<http://nbcr.ucsd.edu/>" Do you have a tutorial that goes in more detail in how to calculate potential with APBS? Thank you, Minju Chun

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Flattening of coloured icosahedron
by R.I.Koning＠lumc.nl 24 Aug '15

24 Aug '15

Is it possible to flatten a coloured icosahedron surface? I have an electron density of a virus, and using shape icosahedron and colour icosahedron surface and surface colour I can colour it according to this density. I would really like to generate a flattened icosahedron (compared to the flatten icosahedron command) from the coloured icosahedron surface. In order to get a 2D map of the colours. Is this possible somehow in Chimera? Is it otherwise possible to export the icosahedron with the coloured surfaces and try in another program (like Maya of Cinema4D?). Best regards, Roman Koning

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layering problem
by Joseph Atherton 20 Aug '15

20 Aug '15

Hi! I'm trying to make videos at the moment but I have a problem with layering, as in the model seems to be 'hiding' behind the density even when the density is transparent. This occurs when I set transparency also in the model, even at low transparency (e.g command #19:transparency 5,a,r #0:259-271). See the example attached- the left hand most part of the model, and the ADP is hidden when their transparency is non-zero. Can I prevent this? Cheers, Joe

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Re: [Chimera-users] [chimera-dev] distance measurements
by Elaine Meng 19 Aug '15

19 Aug '15

Hi Feixia! Yes, you could use Chimera to measure all lysine CA-CA distances in many structures, but it would require some scripting to loop through the structures, find the lysines, and do the measurements. There is some information on looping through structures and running Chimera commands here: <http://www.rbvi.ucsf.edu/chimera/docs/ProgrammersGuide/basicPrimer.html> Now, for each structure, you might imagine the script should first find all the lysines and then use the “distance" command on each pairwise combination, substituting in the proper residue numbers. However, there is an easier way with the “findclash” command. You can use it for multiple distance measurement in a single command. For example: open 2gbp findclash :lys@ca test self overlap -1000 log true … will measure all distances among lysine CA atoms in structure 2gbp and list results in the Reply Log (open from Favorites menu). The -1000 in the command says to measure the distance even if the atoms are “overlapping” by -1000 (more than 1000 angstroms apart). The last column in the results is the atom-atom distance, and they are given in order of increasing distance, in this case: 464 contacts atom1 atom2 overlap distance LYS 191.A CA LYS 189.A CA -1.802 5.562 LYS 227.A CA LYS 223.A CA -2.137 5.897 LYS 300.A CA LYS 246.A CA -2.800 6.560 LYS 169.A CA LYS 164.A CA -4.676 8.436 LYS 270.A CA LYS 276.A CA -4.677 8.437 [… several lines removed …] LYS 276.A CA LYS 203.A CA -53.705 57.465 LYS 276.A CA LYS 137.A CA -56.756 60.516 LYS 61.A CA LYS 137.A CA -56.829 60.589 LYS 58.A CA LYS 137.A CA -59.598 63.358 464 contacts The log contents can be saved to a text file, for example see <http://plato.cgl.ucsf.edu/pipermail/chimera-users/2008-October/003184.html> However, your log would have a huge amount of results for all structures and it might be hard to tell which results go with which structures, so another possibility would be to save a separate file of results for each structure, and in that case your script would need to substitute in an output filename, e.g. findclash :lys@ca test self overlap -1000 saveFile ~/Desktop/2gbp.log See findclash documentation for all the options. Then you can embed the command in the python looping script as described in the first link above. <http://www.rbvi.ucsf.edu/chimera/docs/UsersGuide/midas/findclash.html> I hope this helps, Elaine ----- Elaine C. Meng, Ph.D. UCSF Computer Graphics Lab (Chimera team) and Babbitt Lab Department of Pharmaceutical Chemistry University of California, San Francisco On Aug 18, 2015, at 8:36 AM, Feixia <feixia.chu(a)unh.edu> wrote: > Hi there, > I am interested in retrieving distance information from large dataset in an automatic fashion. For instance, can we use Chimera to get the distances between lysine alpha-carbons of current PDB entries. Presumably, we can download all PDB structures on our local desktop, and just call functions one structure at a time. I wonder if we can do that with Chimera. Your advice will be highly appreciated. > Best, > Feixia

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measure the vertical distance between aromatic planes
by Wang, Bing 19 Aug '15

19 Aug '15

Hi Chimera, Is there a way to measure the vertical distance of two planes in the structure? I do know how to measure the angle between two planes or one line and one plane by the Axes/Planes/Centroids in Chimera. I don't need the distance of two centroid of two planes. I do need the vertical distance of two planes. Could you please show me in detail? Thanks a lot! Bing Wang

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How to select a plane from the command line
by JUAN PABLO REYES VALVERDE 17 Aug '15

17 Aug '15

Dear UCSF Chimera Team: Please, I would much appreciate your advice on the following: First issue: Given a number of planes - calculated/created through the 'define' command - I would like to select one of them, with some command entered at the command line .... How can I do it? The reason why I want to select it through the command line, and not by directly by clicking at it at the axes/planes/centroids table, is because later I would like to use the command inside a runCommand statement, in a Python/IDLE script (with *.py extension) ... Second issue: By the way, do you think this piece of code could work? Assume that the desired plane is already selected .... I want to internally handle the plane as 'p1' in my Python code: p1= chimera.Plane() from chimera import selection p1= selection or perhaps this single instruction ..... p1= chimera.selection Let me try to explain: Within my Python code, I want to have a way to make reference to a plane created by the 'define' command ( should I call it a ' handle'? ... not sure whether it is the correct term ...). Well, I hope that I managed to make it sufficiently clear ... Thanks in advance for your kind attention. Cheers, Juan Dr. Juan Pablo Reyes Valverde Laboratorio de Neurobiología Molecular y Celular (D15) Instituto de Neurobiología UNAM Campus UNAM Juriquilla Boulevard Juriquilla 3001 Querétaro, QRO CP 76230 MÉXICO Tel +52 (442) 2381064

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Charges for PTR+DT
by Amali Guruge 17 Aug '15

17 Aug '15

Dear all, I have to prepare the pdb structure 1K4T to my study. When I do the dock prep process, it gives net charges as, PTR+DT -2 TGP +0 I added charges for standard resides by AMBER ff12SB. For other residues, I added charges by Gasteiger method. My problem is why PTR+DT gives -2 charge? I am not familiar with this one. <http://www.google.lk/intl/en/options/> Can anyone help me? Thank you.

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Modification of ribbon scaling to intersect guide atoms at termini and chain breaks?
by Oliver Clarke 14 Aug '15

14 Aug '15

Suggestion - would it be possible at some point in the future to add a new ribbon scaling option (I guess in Chimera 2.0 or later) so that all internal residues behave like the current “Bspline” scaling, but residues at termini or chain breaks behave like “cardinal” - where the ribbon path exactly intersects the guide atoms? The attached image illustrates the kind of situation this would address - where one wants to show secondary structure in cartoon, but pick out a loop or structural feature of interest in backbone or CA+sidechains, with no ugly discontinuities between the all-atom and ribbon representations. This would allow seamless mixing of nice looking cartoon representation and nice looking backbone or C-alpha+sidechains representation, which I don’t believe is possible at the moment. Cheers, Oliver. Also, in case anyone finds it useful, the following alias applied to a selection or model will generate the CA+sidechains representation depicted below: #Show CA trace with sidechains #Usage: ca_and_sidechains #model_id (or selection/atom-spec) alias ^ca_and_sidechains sel $1; namesel tmp; ~ribbon tmp; ~disp tmp; sel tmp&@CA&protein; repr stick sel; disp sel; setattr m stickScale 1.00 tmp; sel side chain/base.without CA/C1'&tmp; repr stick sel; disp sel; setattr b radius 0.1 sel; color orange tmp; color byhet tmp; sel @CAA |@CB; namesel tmp2; sel tmp&tmp2; repr stick sel; setattr b radius 0.1 sel; sel @CD,N&:pro&tmp; disp sel; repr stick sel; setattr b radius 0.. 1 sel; ~sel

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~select doesn't work on axes?
by Oliver Clarke 14 Aug '15

14 Aug '15

The command "~sel” does not unselect selected axes/planes/centroids - is this intended, and/or is there another way to unselect these objects from the command line? Also, is there a command to undisplay selected axes/planes/centroids? I can only figure out how to do so from the GUI but I would like to do this from the command line, as when you have many axes defined and only want to hide a few it would be easier to have an equivalent of “~disp sel” rather than hunting for the specific axes in the Axes/Planes/Centroids list. Cheers, Oliver.

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odd chimera benchmark performance
by Dan Lin 13 Aug '15

13 Aug '15

Hello: I was wondering if anyone had any experience tracking down performance problems in chimera. I've noticed that I am getting really sluggish performance when managing a lot of atoms, even when everything is shown as backbone traces only. To take a look at the performance, I ran the benchmark and got the following numbers: Volume benchmark scores surface mesh contour solid recolor 981 1291 280 589 393 Null Wire Stick BStick Ribbon Sphere Ops 6249.5 158.7 1.5 0.9 27.4 0.4 89.3 compared to a benchmark posted on the website of the same graphics card: 2125 2026 302 512 491 213 492 452 3259 169 128 Apparently I'm getting awful benchmarks for most of the molecule benchmarks, while the volume performance is pretty comparable. I re-ran the molecule benchmarks to make sure they were reproducible and got pretty much the same numbers. Would anybody have any suggestions for figuring out what's going on? For reference, I'm running ubuntu 12.04 with up to date nvidia drivers for a GTX 560 Ti. Thanks, Dan

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axis-axis distance definition
by Oliver Clarke 13 Aug '15

13 Aug '15

Quick question - how is the distance between two axes (as reported by Axes/Planes/Centroids) calculated? Is it the minimum distance between two axes (I guess yes, because it does not seem to match the center to center distance)? And does it assume the axes are of infinite length, and calculate the displacement required for them to intersect, or does it measure the minimum distance between the axes with the length and end positions as displayed? Cheers, Oliver.

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place label at arbitrary position in 3D
by Oliver Clarke 13 Aug '15

13 Aug '15

In case it is useful to anyone else - I was trying to figure out a way to place a label at an arbitrary position in 3D, so that I can for example generate a chimera session of a protein with all helices labeled and annotated appropriately. I couldn’t figure out a way to easily do this with the built in tools (rlabel, labelopt etc all seem to require you to set an offset from an atom in the structure), so I made the following alias, which gets around this by placing an invisible marker atom at the center of rotation (which I mostly keep locked to the center of view), and attaching a label to that. Hope it is useful to somebody else too. #Place label here (at center of rotation). #Usage: label_here "label_text" (replace spaces in desired label text with _; they will be replaced by spaces in label) alias ^label_here ~sel; ac mc; color black sel; repr bs sel; vdwdefine 0.01 sel; setattr a label $1 sel; transparency 100,a sel; ~sel Cheers, Oliver.

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curved helices - cylinder representation?
by Oliver Clarke 12 Aug '15

12 Aug '15

Hi all, I’d like to have an extended version of the “Pipes and planks” representation, where helices are represented as cylinders, except as a regular, easily modifiable ribbon representation, and allowing for helix curvature rather than breaking up curved helices. I realize this is not currently implemented and is unlikely to be addressed until Chimera 2.0 due to the many other more important things on the drawing board, so I’m trying to figure out a way to hack something together that will generate acceptable results in the meantime. I figure that one way to do this might be to use a create a pdb file with guide atoms located on the helix axis, which one can approximate by placing a guide atom (P or CA) at the center of mass of a six residue sliding window of C-alpha atoms, and then use these guide atoms to create a thick, smoothed (with B-spline) licorice tube. This works quite well for an individual helix, as you can see in the attached pics, but I am a little at a loss as to how to automate this procedure across all the helices in a structure, or even for a given (selected) helix (and it’s only really the helices I care about - strands are fine as is, but having a curved cylinder representation for helices would be very handy). I guess I can do so using a python script of some sort, but if anyone has any pointers as to how to get started, they would be most appreciated. So I guess I need to loop through all the residues in a selection, calculating the center of mass in a sliding window and placing atoms as appropriate, then write out a pdb file with appropriate atom names. This shouldn’t be too hard, but if anyone can point me towards code that I can adapt for this purpose it would be most helpful. Cheers, Oliver.

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question
by A G Szabo 11 Aug '15

11 Aug '15

Today I was trying to Fetch a series of files from the PDB. Their accession codes are 3J7O, 3J7Q, 3J7R, and 3J7P. These are structures of the ribosome complexed with a trimeric translocon, Sec61. Each time Chimera responded with an error message indicating that there was no such file. The files come from a paper by R M Voorhees, (2014) Cell 157:1632. I went to the PDB website and was able to access each of the files. So they do exist. However, when I tried to visualize them using Protein Workshop the structure that appeared was a mixture of surfaces and ribbon structures. I was not able to do anything with any of the structures using Protein Workshop. I could not delete any of the several components, nor change them to ribbon structures. I have been able to fetch, using Chimera, other PDB files that have the entire ribosome complexed with proteins of interest. I sent a message to PDB relating what I have encountered and am waiting for a response. My question to Chimera is to determine if there is a work around to get at any of these files. Thank you Arthur G. Szabo Professor Emeritus Chemistry Wilfrid Laurier University

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is Chimera able to do spin albeling in silico
by Shu-Hao Liou 10 Aug '15

10 Aug '15

Hi, Thank you for reading this email. I'd like to have a rough protein structure with certain spin label on one of the cysteine. Is chimera be able to provide the reasonable structure for that? Sincerely, Shu-hao Liou UC Davis

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Attribute "distance" generated by shortcut "ac sd" not saved between sessions?
by Oliver Clarke 10 Aug '15

10 Aug '15

Hi all, I use the command “ac sd” to color dotted surfaces such as the attached by pore radius (I generate a molmap surface corresponding to the channel axis and then use "ac sd" to generate an attribute “distance", which in this case corresponds to the pore radius, which I can then use to color the dotted surface pdb using Render by Attribute). The dotted surface is generated using the program HOLE (http://www.smartsci.uk/hole/) along with the attached script to make it readable by chimera. This all works fine, however I have noted that the attribute generated by "ac sd” is not present when I reload the saved session, whereas other attributes (e.g. those created explicitly with defattr) are. I can just regenerate it of course, but it would be convenient if it were saved with the session, as it can take a while (~10 minutes) to calculate for large dotted surfaces. Cheers, Oliver.

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A video of 'view dock'
by Amali Guruge 10 Aug '15

10 Aug '15

Dear All, Can we save the movie play in 'view dock' option? Can anyone help me? Thank you.

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Re: [Chimera-users] PDB: 3NZ4 (Chimera vs Pmol Visualization)
by Elaine Meng 07 Aug '15

07 Aug '15

Hi Kevin, What you are seeing is weird-looking bonds between the ribbon and the residues named MDO. It is an artifact caused by the default smoothing of the ribbon path, the amino acid derivation of MDO, and the default hiding of “backbone” atoms in Chimera when the ribbon is displayed. More on that here, if anybody wants details... <http://www.rbvi.ucsf.edu/chimera/docs/ContributedSoftware/ribbonstyle/ribbo…> As you found, you could just show atoms without ribbons to solve the problem. However, if you really wanted to show ribbons at the same time, here are some choices as to what you could do in Chimera to make it look less deformed: (1) enable display of all atoms of the MDO at the same time as the ribbon, for example with command: ribbackbone .. however, side effects you may not like are that this will also show backbone atoms of the other residues that are displayed, and MDO and these other residues may be obviously detached (as if “floating” away) from the smoothed ribbon. You could try hiding the backbone atoms of the other residues with: ~disp @n,c,o & ~:mdo … or you could go back to the original behavior of disabling simultaneous backbone-atom and ribbon display with: ~ribbackbone (2) use a non-smoothed ribbon path that is forced to go through the CA atoms, for example with command: ribspline cardinal … however, this is still ugly because the ribbon makes a sharp turn near this derived residue, and the methyl group comes off of the ribbon at a strange angle. You can go back to the default ribbon path with: ribspline b Sorry, neither makes a beautiful picture. But I hope this helps to explain what is going on. Best, Elaine ----- Elaine C. Meng, Ph.D. UCSF Computer Graphics Lab (Chimera team) and Babbitt Lab Department of Pharmaceutical Chemistry University of California, San Francisco Pictures before and after using “ribbackbone” command:

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PDB: 3NZ4 (Chimera vs Pmol Visualization)
by Kevin D. Walker 07 Aug '15

07 Aug '15

A specialized prosthesis within the PDB 3NZ4 structure looks proper in Pmol but looks skewed in Chimera (my choice), and I wonder why the prosthesis is rendered as such in Chimera? Kevin ---------------------------------- Kevin D Walker Associate Professor Michigan State University Department of Chemistry and Department of Biochemistry & Molecular Biology 578 S Shaw Lane; Room 208 East Lansing, MI 48824 Phone: 517 355 9715 x 257 Fax: 517 353 1793 websites: 1) http://bmb.natsci.msu.edu/about/directory/faculty/kevin-d-walker/current-re…

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clipping and capping
by George Tzotzos 07 Aug '15

07 Aug '15

I’m a real novice in this kind of operation so I shall try in some detail what I’m trying to achieve. I’m dealing with a long serendipitous ligand that spans through a homodimer (2erb) (see screenshot1). I would like to generate something like the B-factor colouring feature (http://www.cgl.ucsf.edu/chimera/features.html <http://www.cgl.ucsf.edu/chimera/features.html>). I’ve opened the Depiction tool and tried surface clipping and capping to no avail. Reading the manual, I figured out that first I have to generate a volume and then use the sop clip command. If this is the routine, I’m seeking advice on how to generate the volume data and then pass it to the sop clip command. As always grateful for your kind help Regards George

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Changing license agreement email
by Flaherty, Daniel P 07 Aug '15

07 Aug '15

Hello, I am using the academic license agreement for Chimera from my previous position at the University of Kansas. However, I have now moved to Purdue and am starting my own laboratory. I would like to utilize Chimera in my lab. I sent an email earlier regarding generating spheres when preparing a protein for docking from my Purdue email and it told me I was not a registered user. I subsequently re-sent the email from my KU email since that is what I was licensed under. Long story short. How to I switch the license agreement to recognize my Purdue email as the registered user? Do I need to un-install Chimera and go through the steps to accept the academic licensing again using my new Purdue email account? Sorry for the confusing email. Thanks! Dan Daniel P. Flaherty, Ph.D. Assistant Professor Department of Medicinal Chemistry and Molecular Pharmacology Purdue University dflaher(a)purdue.edu Office - (765) 494-4761 [cid:8F36A2D2-6664-4FA0-B72D-D785C950B081]

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