solvent flattening

[Gerard Kleijwegt]

In article <1994Mar8.212215.4300 at cs.yale.edu>, johnk at loglady.ninds.nih.gov (John Kuszewski) writes:
|> Could anyone give me a quick explanation of what 
|> solvent flattening is?
|> 
|> -- 
|> John Kuszewski
|> johnk at spasm.niddk.nih.gov
|> I'm not an idiot, but I play one on USENET.

the application of the idea that the solvent region
is featureless (flat) in the electron density

this can be used to improve maps (in particular
initial MIR maps):

- generate a mask (molecular envelope)
- keep the density inside the mask as it
  is, but set all points outside (solvent)
  to a density value which makes the average
  of the map zero
- calc new structure factors
- scale SFs & phase-combine with MIR phases
- calculate a new map

this is an iterative procedure

--Gerard

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               Gerard J. Kleywegt              ___  
  Department of Molecular Biology              | |  /\
                Biomedical Centre             /\ -- ||
               Uppsala University             || || ||
                Box 590, S-751 24             || || ||
                  Uppsala, SWEDEN             || \/ --
                                              --  |__|
    E-mail: gerard at xray.bmc.uu.se
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