Modeling hydration water and its role in polymer folding

Area of Science:

• Chemical Physics
• Physical Chemistry
• Biophysics

Background:

• The hydrophobic effect is a primary driver of protein folding into native states.
• The underlying physics of the hydrophobic effect remains incompletely understood.
• Understanding solvation forces is key to molecular behavior in aqueous environments.

Purpose of the Study:

• To develop an exactly solvable model for the solvation of non-polar molecules in water.
• To elucidate the physical mechanisms driving hydrophobic behavior.
• To investigate protein-like collapse transitions in polymers and adapt the model for diverse molecules.

Main Methods:

• Introduction of an exactly solvable statistical mechanics model for solvation.
• Analysis of the effect of solute presence on water molecule configurations.
• Application of the model to a non-polar homopolymer in aqueous solution.
• Adaptation of the model for aromatic and polar molecule solvation.

Main Results:

• The model demonstrates that reduced water configurations suffice to induce hydrophobic behavior.
• Clear evidence of both 'cold' and 'warm' collapse transitions was observed in the homopolymer model.
• These transitions mimic collapse phenomena seen in proteins.
• The model framework was successfully adapted for aromatic and polar solvation.

Conclusions:

• The reduced configurational entropy of water molecules is a sufficient explanation for the hydrophobic effect.
• The developed model provides a quantitative framework for understanding hydrophobic interactions and polymer collapse.
• The model's adaptability suggests broad applicability in studying molecular solvation in water.