Internal pressure. A fundamental liquid property

Barton, Allan F. M.

doi:10.1021/ed048p156

Cited by 70 publications

(40 citation statements)

References 42 publications

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“…One example of this is the volume dependence of the internal energy, given by the quantity, (dE/dV) T , which is also known as the internal pressure (Barton 1971). Values of (dE/dV) T may be obtained from the coefficients of thermal expansion (␣) and compressibility ␤ ‫ס‬ (−(1/V) (dV/dP)) T , via the thermodynamic relationships:…”

Section: Temperature Dependence Of Protein Structurementioning

confidence: 99%

Some thermodynamic implications for the thermostability of proteins

2001

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An analysis of the thermodynamics of protein stability reveals a general tendency for proteins that denature at higher temperatures to have greater free energies of maximal stability. To a reasonable approximation, the temperature of maximal stability for the set of globular, water-soluble proteins surveyed by Robertson and Murphy occurs at T* ∼283K, independent of the heat denaturation temperature, T m . This observation indicates, at least for these proteins, that thermostability tends to be achieved through elevation of the stability curve rather than by broadening or through a horizontal shift to higher temperatures. The relationship between the free energy of maximal stability and the temperature of heat denaturation is such that an increase in maximal stability of ∼0.008 kJ/mole/residue is, on average, associated with a 1°C increase in T m . An estimate of the energetic consequences of thermal expansion suggests that these effects may contribute significantly to the destabilization of the native state of proteins with increasing temperature.Keywords: Protein stability; thermal expansion; protein volumes; stability curveThe temperature dependence of the free energy change, ⌬G(T), for protein unfolding:under a given set of conditions (pH, ionic strength, reduction potential, etc.) may be conveniently represented by the stability curve (Becktel and Schellman 1987) as depicted in Figure 1. When the heat capacity is temperature independent, the stability curve is determined by the values of three parameters, T m , ⌬H m , and ⌬C p through the relationship (Hawley 1971;Privalov and Gill 1988):in which T m is the temperature of heat denaturation with ⌬G(T m ) ‫ס‬ 0; ⌬H m is the enthalpy of unfolding at T m ; ⌬C p is the heat capacity change on unfolding. The positive ⌬C p of protein denaturation likely reflects the exposure to water of hydrophobic groups that were buried in the native state. One consequence of ⌬C p > 0 is that the stability curve is indeed a curve (Brandts 1964), and it shows a free energy of maximal stability at a temperature T*. In addition to T m , there is a second point on the stability curve where ⌬G is also equal to zero that corresponds to the phenomenon of cold denaturation (Privalov 1990). The stability curve may be approximated as a quadratic function of the temperature with a free energy of maximal stability occurring at a temperature T* (Zipp and Kauzmann 1973;Stowell and Rees 1995), in which:

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Section: Temperature Dependence Of Protein Structurementioning

confidence: 99%

Some thermodynamic implications for the thermostability of proteins

2001

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“…where n is a dimensionless ratio which has been related to the strength of the intermolecular forces in the liquid 11 and may also indicate the likely validity of the solvation pressure model. For example, n Ϸ 1 for nonpolar liquids and n Ϸ 0.43 for ethanol.…”

Section: Introductionmentioning

confidence: 99%

Solvation pressure in ethanol by molecular dynamics simulations

2007

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The results of all-atom molecular dynamics simulations of ethanol liquid and vapor using a modified version of the Cornell field ͓W. D. Cornell and P. Cieplak, J. Am. Chem. Soc. 117, 5179 ͑1995͔͒ are presented. Excellent agreement with experiment is obtained for density, compressibility, and cohesive energy density. The ethanol liquid is subjected to uniform hydrostatic pressure in the range −1 to 15 kbar at room temperature and the vibrational frequency spectra are calculated. The peak frequencies of seven major vibrational modes are found to be accurate to within 100 cm −1 of their experimental positions and the change of frequency as a function of pressure is consistent with Raman data. The change in bond length is found to be consistent with the solvation pressure model for all bonds except for O-H due to hydrogen bonding.

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“…The third goal is determination of the (p, T ) data of internal pressure which is closely related to the liquid structure, i.e. describes macroscopic effect of molecular interactions and plays an important role in the physical chemistry of the liquid state (Barton, 1971;Dack, 1975;Marcus, 2013). Investigations are completed by determination of the acoustic impedance Z in the given above (p, T ) range and all the present studies are based on the (p, T ) speed of sound data reported recently (Dzida et al, 2013).…”

Section: Introductionmentioning

confidence: 99%

Acoustic Nonlinearity Parameter B/A, Internal Pressure, and Acoustic Impedance Determined at Pressures up to 100 MPa for 1-Ethyl-3-methylimidazolium bis[(trifluoromethyl)sulfonyl]imide

Zorębski¹,

Dzida²

2016

Archives of Acoustics

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The nonlinearity parameter B/A, internal pressure, and acoustic impedance are calculated for a room temperature ionic liquid, i.e. for 1-ethyl-3-methylimidazolium bis[(trifluoromethyl)sulfonyl] imide for temperatures from (288.15 to 318.15) K and pressures up to 100 MPa. The B/A calculations are made by means of a thermodynamic method. The decrease of B/A values with the increasing pressure is observed. At the same time B/A is temperature independent in the range studied. The results are compared with corresponding data for organic molecular liquids. The isotherms of internal pressure cross at pressure in the vicinity of 70 MPa, i.e. in this range the internal pressure is temperature independent.

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Internal pressure. A fundamental liquid property

Abstract: In order to discuss the expected relationship between internal energy and molar volume, it is first necessary to look at the dependence of energy on distance on a molecular scale.

Cited by 70 publications

References 42 publications

Some thermodynamic implications for the thermostability of proteins

Some thermodynamic implications for the thermostability of proteins

Solvation pressure in ethanol by molecular dynamics simulations

Acoustic Nonlinearity Parameter B/A, Internal Pressure, and Acoustic Impedance Determined at Pressures up to 100 MPa for 1-Ethyl-3-methylimidazolium bis[(trifluoromethyl)sulfonyl]imide

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