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Re: [Chimera-users] Changing charge of protein
by Elaine Meng 22 Apr '11

22 Apr '11

Dear Monisha, If you get a Chimera daily build (version 1.6, whereas you probably have 1.5), there will be AddH options for all those residue types I mentioned. The options in AddH are for the side chains. The N-terminus of the backbone will already get a +1 charge, and the C-terminus -1. If the backbone N is not the N-terminus, it is in an amide group and will not be formally charged. However... There is a limit as to what total charge is reasonable for a given protein sequence. If you just arbitrarily increase positive charges everywhere to try to reach some value (why??), it will become less representative of reality. Another approach you might consider if you are trying to make your "system" more neutral is to add counterions (see Tools... Structure Editing... Add Ions). 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 Apr 22, 2011, at 11:47 AM, Monisha Hajra wrote: > Dear Elaine, > > Thank you for your reply. > > However I find in AddH option, its only Histidine specific, what should I do if I want to alter specific protonation state of Lys, Arg. > > Also, read from the link that you had send is that > "lysine positive or neutral > • charges for the neutral LYN residue are assigned if the atom named NZ has atom type N3 and thus two attached hydrogens rather than three" > Is that mean that I can't create +2 charge for Lys, by adding another H to N (which is attached to alpha C)? > > I tried even by command line " addh #0: 34@N", its showing error, though chain #0: 34@N is showing the N atom. > > Kindly provide some solution. Right now charge of my protein is -22, I have to bring it up to +10. Really appreciate on general comment of yours on how do do that? > > Regards > Monisha > > On Fri, Apr 22, 2011 at 9:38 PM, Elaine Meng <meng(a)cgl.ucsf.edu> wrote: > Dear Monisha, > The charge of the protein is the sum of the charges of its residues, but charges are not saved in PDB format. > > Maybe you mean you want to control the protonation state and thus the formal charges of certain residues (for example, specifying which histidines should be positive and which should be neutral)? That can be done when you are adding hydrogens. In the AddH tool (under Tools... Structure Editing) there is "Protonation states for" setting for controlling protonation states of histidine, glutamic acid, aspartic acid, lysine, and cysteine residues. You would have to decide yourself which residues should be in which states. You could indicate that by editing the input PDB file to contain special residue names, or just choose "specified individually" for it to go through and ask you about each one. Details: > <http://www.cgl.ucsf.edu/chimera/docs/ContributedSoftware/addh/addh.html> > > Then, you could save the PDB file including the hydrogens using "File... Save PDB" in the Chimera menu. > > Charges are a somewhat separate matter, and are not saved in PDB files. There would not be any charge assignments until after you used Add Charge (under Tools... Structure Editing). Then, you could see the atom and residue charges in histograms in Render by Attribute, or save them to a file using that tool. If you really meant you wanted to assign specific charges to specific atoms yourself, you could do that with Define Attribute or the command setattr. You can label atoms with their charges as described here > <http://www.cgl.ucsf.edu/chimera/docs/ContributedSoftware/addcharge/addcharg…> > but we don't have that for whole residues. > > 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 Apr 22, 2011, at 5:20 AM, Monisha Hajra wrote: > > > Dear User, > > Is there any way to increase or decrease total charge of the protein in Chimera? Can I see the residue wise (not atom wise) charge and modify, and should be able to save the modified protein in pdb. Trying to look to add charge / "render by attribute" section, but didn't get much help. > > Any help will really be appreciated. > > Regards > > Monisha > >

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Why sym # group h did't work
by Fang, Shunming (NIH/NIDDK) [C] 22 Apr '11

22 Apr '11

Hello, There, I tried several time to use the commend sym #1(or 2,3..), group h, 11.75, 101.32 to my em map, it always show errors saying unknown keyword 11.75, 101.32? Please help me, Thanks Shunming

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Changing charge of protein
by Monisha Hajra 22 Apr '11

22 Apr '11

Dear User, Is there any way to increase or decrease total charge of the protein in Chimera? Can I see the residue wise (not atom wise) charge and modify, and should be able to save the modified protein in pdb. Trying to look to add charge / "render by attribute" section, but didn't get much help. Any help will really be appreciated. Regards Monisha

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Command line
by Ryan Doherty 21 Apr '11

21 Apr '11

I searched the online documents and was unable to find out how to perform certain actions via the command line. Can you let me know how to perform the following commands via the command line: Color secondary structure (and set color for Helix, Strand & Coil) Create a text file with a summary of attributes (ie. # of ions, # of ligands, # of chains, areaSAS for each selected residue) Color surface based on hydrophobicity Thanks! Ryan

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help with command line selections
by Corey Fugate 21 Apr '11

21 Apr '11

I'm having a hard time figuring out how to select secondary structural elements from the command line. Can someone help me with this? Corey

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Command line
by Ryan Doherty 20 Apr '11

20 Apr '11

I searched the online documents and was unable to find out how to perform certain actions via the command line. Can you let me know how to perform the following commands via the command line: Color secondary structure (and set color for Helix, Strand & Coil) Create a text file with a summary of attributes (ie. # of ions, # of ligands, # of chains, areaSAS for each selected residue) Color surface based on hydrophobicity Thanks! Ryan

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dock prep error in chimera
by Daron Standley 20 Apr '11

20 Apr '11

Hi- I just submitted the following bug report to chimera. Sorry if this is a redundant report, but I thought perhaps an experienced chimera user could identify my problem, since I am new to using this tool. I am trying to prepare a ligand for docking. I want to prepare the 4 ribonucleotide monophosphates AMP, GMP, UMP, and CMP. First, I tried extracting these from the Zinc database, but I kept getting related but not quite correct molecules. So, I then tried preparing the molecules in Chimera. My procedure was: 1. Chop up an RNA molecule from the PDB (e.g., 2xnz.pdb) into 'residues' (that is, a single ribonucleotide monophosphate) using a simple perl script. 2. Optional step 2 (I tried both with and without this step): add an oxygen fromt the previous residue to the phosphate and name it ' OP3'. 3. Save each molecule as an individual pdb file (e.g., 2xnz-G-1.pdb for the first GMP) 4. Read one of the newly created pdb files into chimera 5. run Tools->Structure Editing-> AddH In either case (with or without step 2) I get the error below. I have attached both pdb files (bug.zip) for reference. ####################### Error Log ####################### Error in ':ALA': underlying C++ Selectable object is missing Traceback (most recent call last): File "/Applications/Chimera.app/Contents/Resources/lib/python2.7/site-packages/Pmw/Pmw_1_3/lib/PmwBase.py", line 1747, in __call__ return apply(self.func, args) File "/Applications/Chimera.app/Contents/Resources/share/chimera/baseDialog.py", line 346, in command getattr(s, buttonFuncName(txt))() File "/Applications/Chimera.app/Contents/Resources/share/chimera/baseDialog.py", line 564, in OK self.Apply() File "/Applications/Chimera.app/Contents/Resources/share/AddH/gui.py", line 265, in Apply hisScheme=hisScheme, okCB=self.cb) File "/Applications/Chimera.app/Contents/Resources/share/AddH/unknownsGUI.py", line 272, in initiateAddHyd okCB() File "/Applications/Chimera.app/Contents/Resources/share/DockPrep/__init__.py", line 194, in <lambda> cb=lambda pap=_postAddPrep, mols=mols, kw=kw: pap(mols, **kw)) File "/Applications/Chimera.app/Contents/Resources/share/DockPrep/__init__.py", line 259, in _postAddPrep method=method, cb=lambda ur, uc, m=mols, kw=kw: File "/Applications/Chimera.app/Contents/Resources/share/AddCharge/__init__.py", line 117, in initiateAddCharges chargeModel=chargeModel, nogui=nogui, showCharges=labelStandard) File "/Applications/Chimera.app/Contents/Resources/share/AddCharge/__init__.py", line 199, in addStandardCharges for r in m.residues: ValueError: underlying C++ Molecule object is missing ValueError: underlying C++ Molecule object is missing File "/Applications/Chimera.app/Contents/Resources/share/AddCharge/__init__.py", line 199, in addStandardCharges for r in m.residues: See reply log for Python traceback. ####################### End Error Log ####################### Best regards, Daron

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animation
by Jean-Paul Armache 20 Apr '11

20 Apr '11

hello, i would like to ask a question about animation. i would like to achieve the following: 1. i have 3 different volumes, so when i put them next to each other, i would like to have each of them to rotate around it's own axis. an additional feature would be to start the rotation of each of the volume at a different point of time. 2. i would like to make certain parts of pdb appear slowly, either through change of colors from transparency or nucleotide/aminoacid at a time. 3. i would like the colors of a specific volume/pdb to "pulsate", meaning to start up with color nr 1, through 2 or 3 different colors to color nr 2. at the present moment i don't really know how to do those, would you have any hints ? thank you best regards, JP Armache

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trajectories for movie making
by Justin Pahara 20 Apr '11

20 Apr '11

Hello All, I am interested in learning how to write and implement code that defines a pathway through a molecular model in chimera (I want to make movies this way rather than moving and rendering frame by frame through the scene. I'm far more biochemist than computer scientist, so I'm hoping to find material that will allow me to learn from the basics. Q's that I have: 1)how do I define a trajectory start point and end point in the chimeraff 3D viewing space 2)how do I define movement and/or velocity through the 3D space (how do I find define particular reference points in 3D space using chimera) 3)how do I define the incremental steps in in the trajectory (so I can achieve high frame rate or low frame rate videos) 4)can I use the utility function to make a movie/export pov files of the pathway? I greatly appreciate all suggestions! thanks, Justin.

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measure volume for protein subsections
by Anke Mulder 19 Apr '11

19 Apr '11

Hi, I have used segger to divide my reconstruction into protein monomers, and I know how to measure the volume and other attributes of the protein monomer, however, I would like to be able to measure subsections of the monomer so that I can have an idea of what the volume of protein is that, for example, is buried in the lipid bilayer, etc. I thought that I could use clipping planes to do this, but from what I can tell the volume measurement still takes into account the volume of the entire protein. Thanks so much. Anke M.

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