Hi Elaine: LEaP does not understand capping, with a pdb file that Chimera understands perfectly. I have asked for light at both the Amber and Dock sites. Even Dock uses LEaP for amber score. LEaP adds and exta H to the terminal/beginning and OXT to the terminal/last. Moreover, it tries to join the first ACE with last NME. I have not tried separating the capping residue with TER. francesco ---------- Forwarded message ---------- From: Francesco Pietra <chiendarret@gmail.com> Date: Tue, Oct 21, 2008 at 10:34 AM Subject: Re: [Chimera-users] Pruning pdb graphically To: Elaine Meng <meng@cgl.ucsf.edu> Hi Elaine: I had fully protonated histidine and left the chain amino group of lysine in basic form! No excuse for that. Now the charge is 5.0000 so that I expect that dockprep (avoiding add-h!) will work. In my (brief) experience, Chimera is an excellent tool also for capping, especially if Add-H is revised for the cases of capped residues. In some cases (12 residues capped in my case) that is important. Also because I want to run MD under various pH conditions, so that capping will change (constant pH MD is not possible with Amber under explicit medium conditions). That Amber has updated to PDB rules is good news. Perhaps I was so suspicious because a few days ago I found a bug with the latest version of ambpdb (Amber's tool to get a pdb file from inpcr/prmtop): the N-hydrogen names for LEU as first residue are written incorrectly. A revised ambpdb is forthcoming. Regards francesco On Tue, Oct 21, 2008 at 12:49 AM, Elaine Meng <meng@cgl.ucsf.edu> wrote:
After looking at more parameter files, I now believe that Amber and PDB atom names in standard residues, including hydrogens, are the same. My previous information was old (I haven't run Amber for 10 years!), sorry about that. You would still need to worry about correctly naming any atoms changed or added with Build Structure, though.
Besides the Amber *lib files mentioned before, you can also look up the standard atom names in the links from this PDB page: http://remediation.wwpdb.org/downloads.html
Elaine
On Oct 20, 2008, at 2:39 PM, Elaine Meng wrote:
I forgot to mention that usually you don't need to worry about the atom names, as Add Charge knows which PDB names go with which Amber names/charges, and AddH uses the standard names.
I think you only have to worry about the names of atoms that were changed or added "manually" in Build Structure, and if the nonhydrogen atoms have the standard names (PDB = Amber for nonhydrogen atoms in standard residues), AddH will use correct names for the hydrogens later added to those atoms. If you use hydrogens added by Build Structure, however, you have to fix their names.
Elaine