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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