Hydrophobic interactions: an overview

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.

Biopolymer Surfactant Interactions

“…The interaction of protein with other ingredients, mostly cationic and anionic surfactants, is of particular interest because they are used co-operatively in formulated complexes. The mechanisms for the protein-surfactant interactions are polyelectrolyte absorption [9], hydrophobic [10] and ionic interactions [11], depending on the substrate and type of proteins involved. The effect of adding a hydrophilic counterion, NaCl to aqueous CTAT solution was measured by dynamic light scattering.…”

Protein adsorption onto polyester surfaces: Is there a need for surface activation?

“…Currently, the Andrade and Hlady model is one of the most accepted models for protein adsorption 15 and describes an initially weak interaction, followed by protein denaturation that promotes stronger adhesion. The mechanisms governing the protein-polymer interactions could be polyelectrolyte absorption, 16,17 hydrophobic 18 and ionic interactions, 19 depending on the substrate and type of proteins involved. Importantly, it depicts multilayer adsorption with the outer layers weakly and reversibly adsorbed.…”

Nanoscale Hydrophobic Interaction and Nanobubble Nucleation

“…The classical theory of molecular hydrophobicity [1] assumed that an increased ordering of water occurs around hydrophobic molecular groups, namely, the hydrophobic attraction is mainly driven by the gain in entropy [12]. However, the molecular hydrophobic attraction (e.g., between a pair of methane molecules in water) has been proven short ranged 4-8 A with the barrier to dissociate comparable to the thermal energy [4,15,16] and is thus unlikely responsible for the thermal stability of protein assemblies [17].…”