April 2004 - Chimera-users - RBVI Mailing Lists

correction re sessions
by Elaine Meng 31 Mar '04

31 Mar '04

Hello, in my previous message about saving parts of PDB files, I included some text from older replies to users, and this part about sessions is no longer true: >The command "save" (or File... Save Session As... ) doesn't save coordinates, >only how they are positioned/colored/displayed, etc. In fact, restarting >a saved session will use the original input file(s) for coordinates. Actually in the last few versions, the session files do include coordinates and do not look for the original input files. Sorry about that, Elaine

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writing out part of a PDB
by Elaine Meng 31 Mar '04

31 Mar '04

Hi Shuanghong, Question (1), surface problem: I don't think the problem where nothing happens when you type the command "surface" has been reported. Sometimes there is a delay while the surface is being calculated, but it shouldn't be terribly long. Problems have been reported in some cases, but they generally cause some sort of error message. To register a problem more formally, you could send mail to chimera-bugs(a)cgl.ucsf.edu and be sure to include what version of Chimera and what kind of computer you are using, and what structure(s) cause the problem. Question (2), writing out part of a PDB file: If you are on a **non-Windows** system, you can use the command "pdbrun" to save just the atoms that are displayed. You could display only the atoms you want by first selecting what you want to measure the distance to. Then, use Select...Zone... to select all the atoms in the region you want to write out. Then the command "show sel" will undisplay the rest of the stuff. (Or, instead of selecting you could do it all in one command, for example show :212.a za<4.5 for all atoms within 4.5 A of any atom in residue 212 of chain A. Specifying zones in the command line is described in the manual page on atom specification, which is listed in the Basic Functions index.) Next, use pdbrun (see man page using the command "help pdbrun"), for example: pdbrun nouser cat > myzone.pdb Pdbrun literally sends the information for only the displayed atoms in their displayed positions to another command, in this case "cat" to send the information to the file myzone.pdb. If you want the coordinates to be the same as in the original file, first use the command "reset." The command "save" (or File... Save Session As... ) doesn't save coordinates, only how they are positioned/colored/displayed, etc. In fact, restarting a saved session will use the original input file(s) for coordinates. The command "write" (same as the function "write PDB" in the Model Panel) saves coordinates into a file. However, these will save the entire coordinates whether displayed or not. If you are on **Windows** the only way I can think of is to actually delete the atoms/bonds you don't want to write out ("delete" command or Actions... Atoms/Bonds... delete). For example, when only what you want to write out is displayed, delete @/!display actually deletes the other stuff. Subsequently, a file created with "write" would only contain the atoms/bonds that had not been deleted. I hope this helps, Elaine =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-= Elaine C. Meng, Ph.D. Computer Graphics Lab and Babbitt Lab meng(a)cgl.ucsf.edu http://www.cgl.ucsf.edu/home/meng/index.html =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=

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crashing when calculating larger surfaces
by Elaine Meng 31 Mar '04

31 Mar '04

>From eperozo(a)virginia.edu Wed Mar 31 15:15:53 2004 >Sorry to bother you, but I'm having terrible problems with the generation of >surfaces. The program crashes as soon as I request a surface to be built (a >tetramer with ~250 residues/monomer). Interestingly, I don't seem to have >problems with a smaller protein (120 residues). When it crashes it gives me >exit code - 1073741819. Tried two versions of chimera in two different >computers. Same result. >Is this a known bug? >Thanks in advance. >Eduardo Hi Eduardo, It is a known problem that the surface routine is a memory hog. If you are on a unix-type machine it might help to type "unlimit" in the shell before starting Chimera. Otherwise, it might just be trying to use more memory than your machines have. We have been using code developed elsewhere, MSMS, for these surfaces. Due to memory/robustness problems, we are generating some code in-house which will eventually replace MSMS. However, this is still in progress, and has not been incorporated into any Chimera release. You could try deleting extra monomers before using surface or instead show the low-resolution surface generated by the Multiscale Models tool (although it builds multimers with matrix info, even if there is no matrix info, it will still show the low-res surface for the structure you have open). Tools...Multiscale... Multiscale Models, click the "Make models" button. Then if you select All chains (button near the top) you can change the Resolution value and then click Resurface to see different levels of detail. There is a man page for this tool in the Tools section of the User's Guide if you want more info. If you want to register the problem more formally, please send a message to chimera-bugs(a)cgl.ucsf.edu including version, platform, and an example or few of which structures (e.g. their PDB IDs) cause the problem. Best, Elaine

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