One solution from Ian Tickle:
Use the CALC option in SFTOOLS to add the phase shift, i.e. 180*l for
(0, 0, 1/2) and
A'=Acos(180*l), B'=Bcos(180*l), C'=C, D'=D for HL coefficients.
I have not tried it, but I think it should work.
Another more general solution:
Build crude models in the maps. The model can be very crude for this
purpose. Shift the origins of your pdb file using MOLEMAN. Calculate
a map from your origin shifted pdb file using SFALL. Now you can
shift the origins of your experimental phases by RESOLVE or
CPHASEMATCH using the phases derived from the origin shifted pdb as
the reference. Now the reference phases and experimental phases have
the same cell constants and space group, the origin shifted
experimental phases will not be distorted.
-- Jianghai
On Jun 7, 2008, at 4:25 AM, Tommi Kajander wrote:
Dear Jianghai, can you let me know if you figure it out, i would be
interested to know if there is a solution, i have a similar problem..
thanks,
best,
Tommi
Thanks. Unfortunately, the space groups are different and cell
constants are not that close to each other. The phases are actually
from a cross-crystal averaging calculation. But the origins are
different.
-- Jianghai
On Jun 6, 2008, at 12:31 PM, Kevin Cowtan wrote:
cphasematch will do that for you. Pick the "Phase comparison" task
from the clipper-utilities moledule. Select the 'Match origin and
hand' button, and an output MTZ box appears.
It'll work out the shift for you, as long as you have some sort of
phases for both cases.
This'll only work though if the cell constants are close enough that
you can actually merge the MTZ's sensibly. If that is not the case,
you are really looking at a cross-crystal averaging calculation.
Jianghai Zhu wrote:
Hi All,
I have a data set with experimental phases. I would like to shift
the origin of the phases so that it matches the origin of another
data set and phases, which has different cell constants. Any
suggestion of what tools has the ability to do this? i.e. shift
the origin by (0.0, 0.0, 0.5). Thanks.
-- Jianghai
--
Tommi Kajander, Ph.D.
Macromolecular X-ray Crystallography
Research Program in Structural Biology and Biophysics
Institute of Biotechnology
P.O. Box 65 (Street address: Viikinkaari 1, 4th floor)
University of Helsinki
FIN-00014 Helsinki, Finland
Tel. +358-9-191 58903
Fax +358-9-191 59940
