Thanks for kind advices.

Whatif and PISA worked excellently, but I want to get the list within Pymol.
 
By parsing the pymol modules, I found

hb = cmd.find_pairs("((byres "+sss1+") and n;n)",
                              "((byres "+sss1+") and n;o)",mode=1,
                              cutoff=3.7,angle=55,
                              state1=state,state2=state)
 
in util.py. Is it possible to get a list of main-chain hydrogen bonds with this function?
 
Any suggestions and advices are welcomed.
 
Thanks in advance.
 
Tomoko