Re: [ccp4bb]: Histogram matching for high solvent crystals

["David J. Schuller" <djs63@cornell.edu>]

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

On Mon, 24 Jun 2002, Byron DeLaBarre wrote:

> My question is with regards to histogram matching during phase improvement-
> 
> Is histogram matching valid when a crystal falls outside of the normal range
> of solvent/protein ratios?
> I have a crystal that appears to be ~70% solvent.
> 
> I am using 'dm' to do the phase modification.
> 
> I am unsure of the extent that histogram matching contributes to phase
> improvement, so maybe this is a non-issue.  Still, it would be nice to
> know...

histogram matching generally helps in DM, and at no extra charge!
i recommend it.

HM concerns the distribution of density within the protein region, so it 
should not be dependent on the amount of solvent and the histograms should 
be correct for your protein region. in your example the contribution will 
be somewhat limited because HM is improving only 30% of your asymmetric 
unit.

there have been a few papers on double histogram matching, you might look 
those up in your spare time.

cheers,

=======================================================================
A skeptic as to all ideas, including especially my own, I have never suffered
a pang when the ideas of some other imbecile prevailed. - H.L. Mencken
=======================================================================
                        David J. Schuller
                        modern man in a post-modern world
                        MacCHESS, Cornell University
                        djs63@cornell.edu