[phenixbb] Split Occupancy of a ligand and water
Pavel Afonine
pafonine at lbl.gov
Mon Mar 28 14:42:25 PDT 2011
Hi,
> Use different altloc tags in the PDB (Column 18). For example:
>
> HETATM 2142 O AHOH 1009 1.332 -11.668 14.957 0.50 6.57 O
> HETATM 2143 O BLIG 1010 7.403 -7.755 -0.773 1.00 29.28 O
>
> Then it will know they don't occupy the same space at the same time.
> As a word of warning the occupancy refinement of two proximal atom
> that don't have the same residue number can sometimes add up to more
> than 1 so check to make sure the model makes physical sense.
if you assign them the same residue number, in the example above that
would be
HETATM 2142 O AHOH 1009 1.332 -11.668 14.957 0.50 6.57 O
HETATM 2143 O BLIG 1009 7.403 -7.755 -0.773 1.00 29.28 O
then the sum of occupancies occupancy(AHOH) + occupancy(BLIG) will be 1
exactly. Please let me know if it is not the case.
An example of similar thing is:
http://www.rcsb.org/pdb/files/1EJG.pdb
see residue number 22 for example. Although that software didn't do it
quite right (I mean occupancy grouping and constraining).
Pavel.
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