On 28/04/16 05:51, Xiao Lei wrote:

Hi Phenixbb members,

Is there a way in the Coot GUI that I can build two helix of the same sequence (or just short 5aa or 6aa peptide chains of the same sequence) that run in the opposite direction (180 degree opposite direction) of each other and set half occupancy of each peptide chain?

I tried to use Calculate---> Model/fit/refine/----> add alternative conformation, but it seems I only have two options: "split single residue at C-alpha" or "split all of a single residue", which are applying to single residue only, not a short peptide chain.

There isn't a single button to do it, this is what I would do:

Make a molecule of my favourite 6aa helix, centre the blob(?) in which you wish to put it at the centre, Move molecule here. Jiggle Fit (as needed), mutate residue range, [1], Extensions-> Modelling -> Copy Molecule, Other Modelling Tools-> Reverse Fragment, Ca Zone -> Main-chain, R/RC [Add Alpha helix restraints], mutate residue range. Refine (or Regularize as needed)

(Using modern Coots)
[1] Scripting -> Python -> set_occupancy_residue_range(1, "A", 1,6, 0.5) # or some such

Paul.