dorsal/arxiv
View SchemaHydrophobic Effects on a Molecular Scale
| Authors | G. Hummer, S. Garde, A. E. García, M. E. Paulaitis, L. R. Pratt |
|---|---|
| Categories | |
| ArXiv ID | physics/9807001 |
| URL | https://arxiv.org/abs/physics/9807001 |
Abstract
A theoretical approach is developed to quantify hydrophobic hydration and interactions on a molecular scale, with the goal of gaining insight into the molecular origins of hydrophobic effects. The model is based on the fundamental relation between the probability for cavity formation in bulk water resulting from molecular-scale density fluctuations, and the hydration free energy of the simplest hydrophobic solute, a hard particle. This probability is estimated using an information theory (IT) approach, incorporating experimentally available properties of bulk water -- the density and radial distribution function. The IT approach reproduces the simplest hydrophobic effects: hydration of spherical nonpolar solutes, the potential of mean force between methane molecules, and solvent contributions to the torsional equilibrium of butane. Applications of this approach to study temperature and pressure effects provide new insights into the thermodynamics and kinetics of protein folding. The IT model relates the hydrophobic-entropy convergence observed in protein unfolding experiments to the macroscopic isothermal compressibility of water. A novel explanation for pressure denaturation of proteins follows from an analysis of the pressure stability of hydrophobic aggregates, suggesting that water penetrates the hydrophobic core of proteins at high pressures. This resolves a long-standing puzzle, whether pressure denaturation contradicts the hydrophobic-core model of protein stability. Finally, issues of ``dewetting'' of molecularly large nonpolar solutes are discussed in the context of a recently developed perturbation theory approach.
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"abstract": "A theoretical approach is developed to quantify hydrophobic hydration and\ninteractions on a molecular scale, with the goal of gaining insight into the\nmolecular origins of hydrophobic effects. The model is based on the fundamental\nrelation between the probability for cavity formation in bulk water resulting\nfrom molecular-scale density fluctuations, and the hydration free energy of the\nsimplest hydrophobic solute, a hard particle. This probability is estimated\nusing an information theory (IT) approach, incorporating experimentally\navailable properties of bulk water -- the density and radial distribution\nfunction. The IT approach reproduces the simplest hydrophobic effects:\nhydration of spherical nonpolar solutes, the potential of mean force between\nmethane molecules, and solvent contributions to the torsional equilibrium of\nbutane. Applications of this approach to study temperature and pressure effects\nprovide new insights into the thermodynamics and kinetics of protein folding.\nThe IT model relates the hydrophobic-entropy convergence observed in protein\nunfolding experiments to the macroscopic isothermal compressibility of water. A\nnovel explanation for pressure denaturation of proteins follows from an\nanalysis of the pressure stability of hydrophobic aggregates, suggesting that\nwater penetrates the hydrophobic core of proteins at high pressures. This\nresolves a long-standing puzzle, whether pressure denaturation contradicts the\nhydrophobic-core model of protein stability. Finally, issues of ``dewetting\u0027\u0027\nof molecularly large nonpolar solutes are discussed in the context of a\nrecently developed perturbation theory approach.",
"arxiv_id": "physics/9807001",
"authors": [
"G. Hummer",
"S. Garde",
"A. E. Garc\u00eda",
"M. E. Paulaitis",
"L. R. Pratt"
],
"categories": [
"physics.chem-ph",
"physics.bio-ph",
"q-bio"
],
"title": "Hydrophobic Effects on a Molecular Scale",
"url": "https://arxiv.org/abs/physics/9807001"
},
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