Monday 26 September 2011

Pointless problems

From: Emmanuel Saridakis
Date: 14 September 2011 19:06

Dear All,

I am having problems when trying to run Pointless with input from
Denzo/Scalepack.

(1) Pointless refuses to work from the .sca file. The error message is:

CCP4 library signal mtz:File not identified as MTZ (Error)
CCP4MTZfile: open_read - File missing or corrupted: rn7e222test.sca

or

The program run with command: /programs/CCP4/ccp4-6.1.1/bin/pointless
has failed with error message
child process exited abnormally

(when run from ccp4i)

(2) Scalepack2mtz refuses to convert a Scalepack file produced using the
command: "NO MERGE original index" (i.e. as instructed by the Pointless
instructions). It fails with the rather tactless message:

*  Resolution Range :
   0.00202    0.00485     (     22.256 -     14.357 A )
 * Sort Order :
     0     0     0     0     0
 * Space group = 'P 2 2 2' (number     16)

 SCALEPACK2MTZ:  Check your data!

And, no my resolution range is not 22.2-14.3 A!!

(3) Pointless refuses to work with an .mtz file produced by Scalepack2mtz
from a .sca file obtained with the simple "NO MERGE" instruction (remember
the "NO MERGE original index" instruction is a no-go for Scalepack2mtz).
The error message in this case is quite simply:

HKLIN is merged and no HKLREF file is defined, SPACEGROUP or REINDEX.

I know the orthodox ccp4 reply would be "stop whining and use Mosflm!",
but is there an alternative if I really want to use Denzo/Scalepack? If
not, is there another way to check my point group/spacegroup starting from
Denzo/Scalepack?

Thanks a lot!

Emmanuel

----------
From: Ed Pozharski
If you are trying to choose the screw axes, you can always look at the
systematic absences. This script may be useful in extracting the (h00),
(0k0),(00l) and such (assuming you used P222 and thus scalepack kept
everything):
http://strucbio.biologie.uni-konstanz.de/ccp4wiki/index.php/Get_systematic_absences_from_.sca_file


Cheers,

Ed.

--
"Hurry up before we all come back to our senses!"
                          Julian, King of Lemurs

----------
From: Phil Evans
Pointless will read scalepack files. From ccp4i you need to select the "Scalepack file" option and give unit cell, see attached screen shot

Failing this you can do it from the command line

pointless << eof
scain file.sca
cel a b c alpha beta gamma
eof

Phil








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