Pressure Reentrant Assembly: Direct Simulation of Volumes of Micellization

Meng, Bin; Ashbaugh, Henry S.

doi:10.1021/la402798f

Cited by 10 publications

(11 citation statements)

References 34 publications

(57 reference statements)

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“…With increasing temperature, the association volume becomes positive and pressure drives hydrophobic assemblies apart above the crossover temperature. Our observations and their qualitative agreement with experiment suggest hydrophobic interactions between individual nonpolar moieties do not drive pressure-induced increases in the critical micelle concentration of surfactants 55 or protein denaturation. 56 Subsequently, pressure effects on mesoscale assembly should account for the volumetric properties for the full hydrophobic assembly.…”

Section: ■ Conclusionsupporting

confidence: 75%

Connections between the Anomalous Volumetric Properties of Alcohols in Aqueous Solution and the Volume of Hydrophobic Association

et al. 2017

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The partial molar volumes of alcohols in water exhibit a non-monotonic dependence on concentration at room temperature, initially decreasing with increasing concentration before passing through a minimum and rising to the pure liquid plateau. This anomalous behavior is associated with hydrophobic interactions. We report molecular simulations of short chain alcohols and alkanes in water to examine the volumetric properties of these mixtures at infinite dilution over a range of temperatures. Our simulations find this anomaly disappears at a crossover temperature, above which the solute volume only varies monotonically with concentration. A Voronoi volume analysis of solution configurations finds that solutes in clusters take up less space than individual solutes at low temperature and more space at elevated temperatures. These changes in cluster volumes are subsequently shown to correlate with the derivative of the solute partial molar volume with respect to solute concentration. The changes in solute volume upon nonpolar solute association impact the response of molecular-scale hydrophobic interactions for assembly with increasing pressure.

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Section: ■ Conclusionsupporting

confidence: 75%

Connections between the Anomalous Volumetric Properties of Alcohols in Aqueous Solution and the Volume of Hydrophobic Association

et al. 2017

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“…While counterintuitive, this negative partial molar compressibility is not thermodynamically inconsistent, as the second law only constrains the sign of the overall system compressibility but not that of any individual component of a mixture. Indeed, negative partial compressibilities have been observed for surfactants 99,100 and ions 101,102 in aqueous solution and from molecular simulations of alcohols and hydrocarbons in water. 17 The solute partial compressibility impacts the concentration dependence of the system compressibility.…”

Section: ■ Results and Discussionmentioning

confidence: 99%

Temperature, Pressure, and Concentration Derivatives of Nonpolar Gas Hydration: Impact on the Heat Capacity, Temperature of Maximum Density, and Speed of Sound of Aqueous Mixtures

Ashbaugh

Bukannan

2020

J. Phys. Chem. B

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The hydrophobic effect is an umbrella term encompassing a number of solvation phenomena associated with solutions of nonpolar species in water, including the following: a meager solubility opposed by entropy at room temperature; large positive hydration heat capacities; positive shifts in the temperature of maximum density of aqueous mixtures; increases in the speed of sound of dilute aqueous mixtures; and negative volumes of association between interacting solutes. Here we present a molecular simulation study of nonpolar gas hydration over the temperature range 273.15–373.15 K and a pressure range −500 to 1000 bar to investigate the interrelationships between distinct hydrophobic phenomena. We develop a new free energy correlation for the solute chemical potentials founded on the Tait equation description of the equation-of-state of liquid water. This analytical correlation is shown to provide a quantitatively accurate description of nonpolar gas hydration over the entire range of thermodynamic state points simulated, with an error of ∼0.02 k B T or lower in the fitted chemical potentials. Our simulations and the correlation accurately reproduce many of the available experimental results for the hydration of the solutes examined here. Moreover, the correlation reproduces the characteristic entropies of hydration, temperature dependence of the hydration heat capacity, perturbations in the temperature of maximum density, and changes in the speed of sound. While negative volumes of association result from pairwise interactions in solution, beyond the limits of our simulations performed at infinite dilution, we discuss how our correlation could be supplemented with second virial coefficient information to expand to finite concentrations. In total, this work demonstrates that many distinct phenomena associated with the hydrophobic effect can be captured within a single thermodynamically consistent correlation for solute hydration free energies.

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“…Equation 10 has been used by several authors. 5 , 20 , 23 , 24 , 28 − 30 Due to the nonspherical geometry of proteins, the integration in eq 11 is more difficult to perform if one is interested in a surface based approach. 28 Similarly, Hirata and colleagues have derived statistical mechanical expressions for the infinitely dilute partial molar volumes using the Reference Interaction Site Model (RISM) integral equation theory coupled to KB theory.…”

Section: Introductionmentioning

confidence: 99%

Infinitely Dilute Partial Molar Properties of Proteins from Computer Simulation

Ploetz

Smith

2014

J. Phys. Chem. B

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A detailed understanding of temperature and pressure effects on an infinitely dilute protein’s conformational equilibrium requires knowledge of the corresponding infinitely dilute partial molar properties. Established molecular dynamics methodologies generally have not provided a way to calculate these properties without either a loss of thermodynamic rigor, the introduction of nonunique parameters, or a loss of information about which solute conformations specifically contributed to the output values. Here we implement a simple method that is thermodynamically rigorous and possesses none of the above disadvantages, and we report on the method’s feasibility and computational demands. We calculate infinitely dilute partial molar properties for two proteins and attempt to distinguish the thermodynamic differences between a native and a denatured conformation of a designed miniprotein. We conclude that simple ensemble average properties can be calculated with very reasonable amounts of computational power. In contrast, properties corresponding to fluctuating quantities are computationally demanding to calculate precisely, although they can be obtained more easily by following the temperature and/or pressure dependence of the corresponding ensemble averages.

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Pressure Reentrant Assembly: Direct Simulation of Volumes of Micellization

Cited by 10 publications

References 34 publications

Connections between the Anomalous Volumetric Properties of Alcohols in Aqueous Solution and the Volume of Hydrophobic Association

Connections between the Anomalous Volumetric Properties of Alcohols in Aqueous Solution and the Volume of Hydrophobic Association

Temperature, Pressure, and Concentration Derivatives of Nonpolar Gas Hydration: Impact on the Heat Capacity, Temperature of Maximum Density, and Speed of Sound of Aqueous Mixtures

Infinitely Dilute Partial Molar Properties of Proteins from Computer Simulation

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