Solvation is key to understanding molecular processes in the cell, as well as to understanding hydrophobic association in many in vitro experiments. While much progress has been made in understanding hydrophobic effects in pure water, mechanisms by which osmolytes modulate these effects are less well understood. I will discuss how osmolytes shift the folding equilibrium of hydrophobic polymers in water based on molecular simulations and free energy calculations. Several stabilizing and destabilizing osmolytes, including urea, trimethylamine-N-oxide and methanol, have been studied in our group in recent years and provide quantitative data on two opposing driving forces: solvent-excluded volume and osmolyte-polymer enthalpic interactions. The former driving force will be discussed in terms of molecular scale density fluctuations, which are underlying entropy-driven collapse transitions in various systems that are presently widely believed to be “energy driven” instead. Finally, the properties of some strongly denaturing osmolytes will be discussed for which the above driving forces are mutually reinforcing.

Hydrophobic polymer collapse: Unravelling molecular mechanisms for osmolyte protection and denaturation

253rd National Meeting (2017)

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