Hydrophobic interactions: an overview

TL;DR

This paper reviews recent advances in understanding hydrophobic interactions, emphasizing the importance of collective effects, and introduces a novel explicit solvent model that captures large-scale density fluctuations to simulate phenomena like hydrophobic polymer collapse.

Contribution

It presents a new density field-based explicit solvent model that efficiently simulates large systems and elucidates the role of solvent dynamics in hydrophobic collapse.

Findings

Collapse driven by vapor bubble formation of critical size

Model enables simulation of larger systems than previous methods

Insights into pressure denaturation of proteins

Abstract

We present an overview of the recent progress that has been made in understanding the origin of hydrophobic interactions. We discuss the different character of the solvation behavior of apolar solutes at small and large length scales. We emphasize that the crossover in the solvation behavior arises from a collective effect, which means that implicit solvent models should be used with care. We then discuss a recently developed explicit solvent model, in which the solvent is not described at the atomic level, but rather at the level of a density field. The model is based upon a lattice-gas model, which describes density fluctuations in the solvent at large length scales, and a Gaussian model, which describes density fluctuations at smaller length scales. By integrating out the small length scale field, a Hamiltonian is obtained, which is a function of the binary, large-length scale field only. This makes it possible to simulate much larger systems than hitherto possible as demonstrated by the application of the model to the collapse of an ideal hydrophobic polymer. The results show that the collapse is dominated by the dynamics of the solvent, in particular the formation of a vapor bubble of critical size. Implications of these findings to the understanding of pressure denaturation of proteins are discussed.