Re: [ccp4bb]: cns to mtz conversion

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

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On Tue, 26 Feb 2002, Tom Lee wrote:

> I solved MAD phases by CNS.  The output reflection file contains
> amplitudes, centoid phases, FOM, and HL coefficients of the reference
> wavelength (low remote) data set.  The map produced by density modification
> in CNS showed clear features of secondary structure.  However, most of the
> side chains are missing.  I'd like to try other refinement/modification
> programs outside CNS -- Resolve, SHARP, wARP, etc.  All of these
> softwares require F, PHIB, FOM, sometimes HL's.  I have no problem
> converting the reflection file into mtz format using f2mtz.  However,
> unlike ccp4, CNS keeps F(+) and F(-) in separate HKL records, and the
> phases, FOM, and HL's are also different between the mates.  Therefore, I
> need to find a way to merge the friedel pairs.  I can probably average the
> F(+) and F(-).  But how to deal with the rest parameters?  To make it
> harder, CNS actually stores the reflections in a sorted way where the pairs
> are not next to each other and the distances between the pairs vary too!
> I believe many of you have met this problem.  What is the best way to solve
> it?  Does anybody have a script for doing this?  My spacegroup is p21.

you mentioned SHARP.  SHARP does not require the phases, you could just 
feed it the MAD atom sites you found in CNS.  so you could input your 
intensity or amplitude data straight into CCP4 from whatever 
processing/scaling programs you used, and have SHARP generate the phases 
for you.

=======================================================================
"Supernaturalism is not, on the whole, friendly to science and technology,
 and there is no use in pretending that it is."  -  L. Sprague de Camp
=======================================================================
                        David J. Schuller
                        modern man in a post-modern world
                        MacCHESS, Cornell University
                        djs63@cornell.edu