Nadine Töpfer wrote: > I am facing a problem concerning a ringlike alpha-helical structure. > My initial crystal-structure has a diameter of 9nm which I want to > shrik down to about 7nm, without destroying the helix. Does anybody > know how to solve this problem using modeller?

I can't think of an automatic way to do this. Your model will be restrained by various distance restraints extracted from the template (e.g. Calpha-Calpha distances) and if you want the diameter to be smaller than in the template, all of those distances would have to be shortened. You would have to do this manually in the restraints file.

Ben Webb, Modeller Caretaker