Re: [ccp4bb]: Q: how to convert CNS density modified file to mtz for arp/warp?

[Anastassis Perrakis <perrakis@nki.nl>]

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Hi -

The obvious answer would be 'use CCP4i' and the utility for importing
data from CNS. Alas, last time I tried it did not work, it is (was?) OK
only for CNS data without phase information.

My tactique is to use an 'awk' script to get an ASCII file with
'H K L Fobs SigFobs PHI FOM' which can then be imported as a formatted
ASCII file via CCP4i and 'f2mtz'. You can not directly import the CNS
file simply because the info extends over 2 lines and 'f2mtz' can not
handle that (at least I could never find out).

If you don't know anything about 'awk' it might be considerably easier
and hopefully educational to simply do the phasing in CCP4 ;-)

Talking about phasing, SHARP has developed a habbit of producing better
maps than CNS or CCP4/MLPHARE (no offence to anybody but it's true to my
knowledge) especially in marginal cases, so if by saying 'some secondary
structures' you mean that 'the map is good but not that great' maybe try
SHARP/Solomon, so you can give to ARP/wARP an easier task.

		Tassos


Woo Cheol Lee wrote:

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> ***          CCP4 home page http://www.ccp4.ac.uk         ***
> 
> Dear CCP4BB readers,
> 
> I tried SAD phasing by CNS and, as the density modifed map
> revealed some secondary structures of the protein, now I want
> to try Arp/Warp to refine the experimental phase. How can I
> convert a reflection file of FOM and 4 HL coefficients to an
> mtz file of SIGMA and PHI columns without any loss of the
> phase information?
> 
> Many thanks in advance...
> 
> Woo-Cheol Lee
> graduate student
> U. Tokyo


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