shivesh kumar wrote:
Dear all,
Can u suggest me any method to detwin the twinning data(2.2A).Any
suggestions are welcome.Thanx in advance.
Shivesh
Hi Shivesh,
For a partially twinned dataset with a twinning fraction not too close
to 0.5, from the command line:
% mkdir my_dir
% sfcheck
>my_dir/
FILE_F my_twinned.mtz
OUT U
TEST Y
<blank line>
This will create a detwinned dataset in the my_dir directory in mmCIF
format (with an .hkl extension). Check the sfcheck_XXXX.ps postscript
file for details. Import into ccp4i using the 'convert to MTZ' option
under 'Reflection utilities' from mmCIF format. If there is an import
error, manually edit the .hkl file, changing "_refln.F_meas_au_sigma" to
"_refln.F_meas_sigma_au".
SHELX can refine the structure and the twinning fraction simultaneously;
you may want to consider this. A dataset with a partial twin fraction
close to 0.5 or perfectly twinned should not be detwinned, use SHELX or
CNS to refine against the twinned data instead.
HTH,
James
--
Dr. James Irving
NH&MRC C.J. Martin Fellow
Division of Structural Biology
Wellcome Trust Centre for Human Genetics
Oxford University
Roosevelt Drive,
Oxford OX3 7BN
UK
email: [EMAIL PROTECTED]
phone: +44 1865 287 550
