This would be pretty difficult, but you know in COOT you can overlap the maps for related chains / hetero dimers/ etc. ( Ask for NCS difference maps in the DRAW menu ] The matrix which converts one set of coordinates to the other is then applied to the electron density so you see the NCS relatd maps together . I usually use the facility to get an averaged map of all copies of a molecule to sped up rebuilding - fix a model with respect to the average and do a fraction of the work - but you could also use it to study the differences between the two active sites.
In fact it may be possible to use this to get a true difference map, but it is complicated and I cannot remember how to do it off the top of my head - you have to output the NCS generated maps then mask the maps then use these maps to generate structure factors, then set up a diff map calculation.. Simpler to just inspect the differences by eye! Eleanor On 10 March 2017 at 22:24, Oleg Zadvornyy <ol...@chemistry.montana.edu> wrote: > Dear All, > > > We are working on a tetrameric protein containing 2 heterodimers which are > related to each other by 2 fold symmetry. There are difference at the > active site between the two heterodimers in the crystals, and we would like > to make a difference map to compare one heterodimer to the other. I would > really appreciate your advise and suggestions how to perform this > comparison. > Thank you, > Oleg > > -- > Oleg A. Zadvornyy, PhD > > Institute of Biological Chemistry, > Washington State University > > 237 Clark Hall > Pullman, WA 99163 > > Tel: (509)-335-9837 <(509)%20335-9837> > Lab: (509)-335-1958 <(509)%20335-1958> >
