Dear Pymol users,
 
I would like to modify a protein pdb file with a "crankshaft" flip, which is the anti-correlated double change: psi(i-1) += delta and phi(i) -= delta. Such a change should leave the protein coordinates unchanged effecting only atoms in residues i-1 and i. However implementation in pymol (see below) changes the coordinates of _all_ residues from i-1 to the C-terminal. Can you help me? Can I somehow do the two changes simultanious?...
 
set_dihedral 21/n, 21/ca, 21/c, 22/n,  148.435 #was 168.4
set_dihedral 21/c, 22/n, 22/ca, 22/c, -83.704  #was -103.7
 
best regards,
 
Jakob