Re: [ccp4bb]: origin definition

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

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On Thu, 6 Feb 2003, Bernard Santarsiero wrote:

> I have a set of phases from an MIR run in SOLVE and a potential molecular
> replacment solution of about half the structure in space group P3.  They
> have different origins in Z since it's either defined by the set of heavy
> atom positions in SOLVE, or the set of coords in the MR search model.  I
> want to compare the SOLVE phased map and the MR sfall/2Fo-Fc map.  I see
> at least two possibilities:
> 1.  mask a map region around the model of the MR solution and move it
> around the phased map; the highest CC should indicate the best overlap of
> the two maps. I think I can use RAVE to do this.
> 2.  calculate a series of phases and list the 00l's with phases. Each set
> is from a set of coords that have been translated in Z. At some point,
> these phases should match those from the SOLVE solution. 
> 
> As for point #2, I can't seem to get sfall or sigmaa to output the
> Hendrickson-Lattman coefficients, which would be useful.  Suggestions?

You could use the MR phases to make a difference map from your MIR data, 
thus locating the heavy atom sites.  That should enable you to place your 
MIR solution on the same origin.

Cheers,

=======================================================================
"Reductionism is one of those words that makes me want
    to reach for my revolver." - Richard Dawkins 
=======================================================================
                        David J. Schuller
                        modern man in a post-modern world
                        MacCHESS, Cornell University
                        djs63@cornell.edu