Conformational equilibria of polar and charged flexible polymer chains in water

Continuum model predictions of the conformational equilibria of idealized p olar and charged linear polymers in water are compared to complementary sim ulations in explicit water. The continuum model of hydration predicts with reasonable accuracy the conformational dependence of the hydration free ene rgy of these solutes observed in the simulations. However, a prerequisite f or accurate predictions is the optimization of the phenomenological paramet ers inherent to the continuum model using the simulation results for a subs et of the solutes, in this case the uncharged polymer and two amphiphilic p olymer chains with a single positive or negative charge on one terminal gro up. Our results demonstrate that the continuum model can be used to discrim inate among the conformational preferences for different sequences of backb one charges. Finally, an unexpected finding of this study is the stabilizat ion in water of the more compact conformations of the polymer chains with a fixed dipole moment. The driving force for this behavior is greater than t he hydrophobic driving force and is electrostatic in nature. (C) 2001 Elsev ier Science Ltd. All rights reserved.