Re: [o-info] peptide connectivity

From: Joe Krahn (krahn@niehs.nih.gov)
Date: Wed Feb 14 2007 - 10:06:13 CST


Karen Champagne wrote:
> Hi All,
> 
> I am having some trouble with a peptide ligand bound
> to my protein.  It is an 8-residue ligand and one of
> the residues is post-translationally modified. 
> Because of this, when I load the model into O none of
> the residues in the ligand are connected (i.e. no
> peptide bonds).  I am wondering how I can tell O to
> connect all the residues?  If I do 'make bond' between
> them all it is fine at first, but after a round of
> refinement the bonds are lost again when I load the
> new model.
> 
> Thanks in advance!
> 
> kc
> 

Try out our automatic atom reconnection tool (by myself and Tom Transue)
here:
http://spdbv.niehs.nih.gov/resources/
(note: The dials stuff there needs updating)

It uses a perl script encapsulated in an O text database object. It has
a list of covalent radii to detect bonds between all atoms. It is not
advanced enough to deal with alternate conformations, but it does a good
job otherwise.

Oh, it also assumes that O's ATOM_Z property is correct. Since RCSB has
dropped the element-aligned atom naming rule, many elements are
mis-detected for ligands in newer PDB files. Maybe Alwyn can implement
the new element column. (Or maybe it's in the latest version which I'm
not using yet?)

Also: I noticed that the listinfo/o-info like that comes with this list
email has links for Alwyn's O pages that are out of date.

Joe

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