Peter Grey wrote:
Dear crystallographers,
I try to solve a MR problem in P21 with several different structures (and
one EM map) as search models.
I would like all solutions to have the same origin so I could compare them
and see their relative positions.
I think a possible solution is to bring the center of mass of all models
(and map) to the same point.
Is there another, easier, solution ?
is there a way, already after molecular replacement, to bring all solutions
to the same origin ?
Thank you for your time,
Peter
Calculate phases from all models and use phasecomparison.. ( GUI
reflection utility)
This gives the origin shift needed for different sets of phases
There are other coordinate only tools like the phenix hyss which were
designed to do it for heavy atom solutions.
Another way I often use is to do the superpose trick
If you have only one molecule in the asymm unit you can superpose one
solution on another and see if the rotation matrix and translation
vector look like a symmetry operator with an acceptable alternate origin.
If you have more molecules you need to check against each solution..
By the way there is a useful table of these in the documentation:
http://www.ccp4.ac.uk/dist/html/alternate_origins.html
Eleanor
