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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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