Hi Joe,
Nigel who wrote elbow+reel is traveling so I'll try to help until he gets a chance to respond.
I very simple suggestion is do manually edit the cif file generated by elbow before you
pass it to phenix.refine; The cif file format is meant to be human-readable.
Another option is to modify the dihedral definitions in reel and to save the file without
running the elbow optimizations again. There is nothing wrong with overriding the
elbow results with your chemical knowledge.
A third idea is to run elbow with the Glutathione from your PDB file as the input, instead
of using the smiles string. That may give elbow a better start.
If phenix.refine rejects your inputs I'd be interested to see the log file with the error messages.
If you send me the Glutathione residue from your PDB file (directly; not to list) I could help more.
Ralf


From: Joseph Brock <[email protected]>
To: [email protected]
Sent: Sat, September 18, 2010 1:09:23 AM
Subject: [phenixbb] Ligand restraints editing with REEL

Hi all,

I'm working on a 1.5A structure that contains a novel ligand within the active site, which is an Arsenic derivative of Glutathione, using the Phenix GUI, version 1.6.4-486.

I have been using the 'Molinspiration' webpage (http://www.molinspiration.com/docu/webme/) to generate a smiles string, which I then feed into ELBOW. Although the structure/chemical restraints of Glutathione should be unchanged by the covalent linkage to arsenic through the cysteinyl sulfur, the resulting restraints file consistently restricts one of the dihedrals to a value that is incompatible with the (quite clear) electron density. This occurs regardless of wether i use AM1 optimization, and is unresponsive to using native Glutathione (which refines into the corresponding density extremely well) as an input geometry file with any of the available 'Use geometry for' options (final geometry, initial geometry, etc).

I then tried opening the output file in REEL and manually changing the corresponding dihedrals to those of glutathione, however after running simple optimization, the resulting restraints file has the same problem, and upon choosing the 'transer geometry and restraints' option (or any option) midway through running the 'eLBOW optimization' or 'AM1 optimization' options, Phenix consistently crashes.

Any advice on how to transfer the origional geometry of native Glutathione to my new ligand effectively would be greatly appreciated. I'm a little confused as to the abilities of REEL, and how to affect them.

Thanks so much in advance.

Cheers,

-Joe.