In Charmm-GUI we have the forcefield options of elnedyn22 and elnedynp22 if in need of an elastic network for the protein. Is anything being lost using elnedyn instead of elnedynp in protein-membrane (solvated in water with ions) simulations? What are the major differences between the two forcefields? I've read through the literature but it is still a bit unclear; a detailed response would be great. Thanks in advance.