Moreover, we found that complete structural transitions can occur with very small bonded parameter changes. A clear structural transition between two stable helices occurs upon increasing the backbone bond-bending angle by a small amount from 110 • to 112.5 • , as shown by the shift in the backbone bond-bending angle and backbone torsion angle distributions with the change in bond-bending angle (Figure ). In this structural transition, the optimal native contact pairs (defined by the smallest average distance in the native structure) change from (i to i + 4) spacing for 110 • , to (i to i + 5) spacing for 112.5 • . The melting point data shows that the (i to i + 4) helix is more stable for the set of force field parameters considered here. Knowledge of the molecular parameters which lead to a helix-to-helix transition provides valuable guidance on how to design foldamers which toggle between the two helices in response to a stimulus, for example. From the heat capacity and native contacts curves computed from REMD simulations with varying θ S,o (Figure ), it is apparent that even small perturbations to the equilibrium value of the sidechain angle have a large impact on the melting point and height of the These findings confirm that constraining the sidechain angles at (360 • -θ B,o )/2 is a valid assumption for maximal stability for these sets of force field parameters used. Significant deviations from the symmetry value in either direction destabilize the helix. We found that backbone torsion stiffness strongly affects cooperativity, whereas angle stiffness has a much weaker influence on cooperativity. In addition, stability (melting point) increases with both angle and torsion stiffness. The heat capacity curves and corresponding native contact fraction curves are given in Figure for an angle force constant of 100/rad 2 and a series of backbone torsion force constants ranging from 0 (no torsion forces) to 4.667.