I would like to build a perfect helix as an initial structure for some further manipulations. 

(Without a good initial structure the homology modelling part I apply later does not converge).

Right now I'm using

to build the sequence, then I save it to a PDB, load it in VMD, set the backbone angles there (to get an alpha helix) save it to another PDB and load at back into modeller.

So I guess my basic question is: Is it possible to set backbone dihedral angles to a specific value? Or is there any other way to use mdl.build_sequence to get an alpha helix?

Thank you & best regards,

Ajasja Ljubetič

National Institute of Chemistry

Slovenia