[phenixbb] what to do with disordered side chains

Ed Pozharski epozh001 at umaryland.edu
Tue Mar 29 14:43:49 PDT 2011

The results of the online survey on what to do with disordered side
chains (from total of 240 responses):

Delete the atoms                                         43%
Let refinement take care of it by inflating B-factors    41%
Set occupancy to zero                                    12%
Other                                                     4%

"Other" suggestions were:

- Place atoms in most likely spot based on rotomer and contacts and
indicate high positional sigmas on ATMSIG records
- To invent refinement that will spread this residues over many rotamers
as this is what actually happened
- Delet the atoms but retain the original amino acid name
- choose the most common rotamer (B-factors don't "inflate", they just
rise slightly)
- Depends. if the disordered region is unteresting, delete atoms.
Otherwise, try to model it in one or more disordered model (and then
state it clearly in the pdb file)
- In case that no density is in the map, model several conformations of
the missing segment and insert it into the PDB file with zero
occupancies. It is equivalent what the NMR people do. 
- Model it in and compare the MD simulations with SAXS
- I would assumne Dale Tronrod suggestion the best. Sigatm labels.
- Let the refinement inflate B-factors, then set occupancy to zero in
the last round.

Thanks to all for participation,


"I'd jump in myself, if I weren't so good at whistling."
                               Julian, King of Lemurs

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