Re: [ccp4bb]: Solvent Flattened Data

["Eleanor J. Dodson" <ccp4@ysbl.york.ac.uk>]

***  For details on how to be removed from this list visit the  ***
***          CCP4 home page http://www.ccp4.ac.uk         ***

Paul Hubbard wrote:
> 
> ***  For details on how to be removed from this list visit the  ***
> ***          CCP4 home page http://www.ccp4.ac.uk         ***
> 
> Hello all,
> 
> I am having trouble using SIGMAA on solvent flattened data, and I can't
> figure out why.
> 
> I have a reasonable model which is about 70% complete, built using
> solvent flattened experimental data to 3.7 Angstroms (no phase
> extension). However when I use this data with the model in SIGMAA, the
> map looks awful. However, when I use the un-flattened data things look
> peachy. I tried swapping FP's with the native data, but no improvement.
> Am I missing something here?
> 
> By the way, just out of curiosity, would it be okay to use FWT and PHFWT
> (WCMB) for solvent flattening? Supposedly this is an unbiased 2Fo-Fc, so
> I would suspect flattening would tidy things up. Just wondering.
> 
> Thanks
> 
> AGS
> 

 I am not quite clear what you mean - I dont think you "solvent flatten"
data - it is a technique to improve phases - the data stays the same..

Two points: 
We find that solvent flattening can often over estimate the FOMs and
that you need to use HL copefficients with SAD data.. 

 
If you have a model and exptl  phases before or after dens. modification
you can get combined FOMS from Refmac5 too.

 Eleanor