Thanks Juegen, 

On Wed, May 09, 2007 at 08:45:16AM -0700, Juergen Bosch wrote:
> Hi James,
> 
> start Coot, and read in your cif file plus a coordinate file containing 
> your ligand. Read in your structure and read in your mtz file as Auto, 
> then you end up with two maps FWTxPHWT and DELFWTxPHDELWT.
> Next go to Calculate / Other Modelling Tools and select Fit Ligand. 
> Since you should have some nice extra density in you difference map 
> select this map to search your ligand in that map. Let Coot do the rest. 
> You can also select flexible ligand docking etc.

I would also add that for a difference map, I'd notch up the signigicance
level to 3 sigmas or so.  And that should reduce spurious hits.
 
> Should work as advertised. Once your ligand is in the position you 
> expect it to be you can run real space refinement using the difference 
> density map at this point. Then go to Calculate/Merge Molecules and 
> select which one you want to merge, save the new coordinates including 
> your found ligand.
> 
> Good luck,
> 
> Juergen
> 
> P.S. this is assuming Coot 0.31, and there's also a Coot BB :-)

                             0.3.1 (and not to be confused with 0.0.31)

> 
> James Pauff wrote:
> 
> >Good day all,
> >
> >I have what may be a very simple question.  I am
> >trying to insert a substrate/ligand into the active
> >site of my enzyme using COOT, into electron density
> >that I have already utilized in "O" for this purpose. 
> >I've created the substrate library file (*.cif) using
> >a pdb file from PRODRG in the ccp4 sketcher.  In COOT,
> >I went to File->Get Monomer..., but when I type the 3
> >letter code, I get nothing.  

OK, Coot should be more informative about what kind of nothing 
you get.

> >Further, I have imported the substrate as a separate
> >pdb file, and can move it close to the active site,
> >but I have no idea how to orient/manipulate the ligand
> >into the electron density.  If I can eventually get
> >the ligand as a monomer into the screen, I still don't
> >know how to manipulate its orientation prior to
> >writing it into the enzyme's pdb, so I guess that I'm
> >just generally stuck here.  

If all else fails, there's alway Rotate/Translate Zone
(in the Model/Fit/Refine dialog). Using that you can drag
and rotate the fragment.

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