A Complete Thermodynamic Characterization of Electrostatic and Hydrophobic Associations in the Temperature Range 0 to 100 °C from Explicit-Solvent Molecular Dynamics Simulations

Abstract

The electrostatic and hydrophobic interactions that dominate the behavior of proteins and other biomolecules exhibit fundamentally different thermodynamic characteristics, and the correct reproduction of these differences is likely to be an important requirement for models that aim to predict the thermodynamics of protein stability and protein−protein interactions. To assess the abilities of some current models to capture these differences, we report here the results of molecular dynamics (MD) simulations examining the association of acetate−methylammonium and methane−methane pairs at 11 different temperatures from −12.5 to 112.5 °C. Simulations were performed using two popular water models (TIP3P and TIP5P), with a total simulation time of 22 μs. With both water models, we find that the acetate−methylammonium salt-bridge interaction is significantly more stabilized by high temperatures (e.g., over the range 25 to 100 °C) than is the methane−methane hydrophobic interaction. At low temperatures however, th...