Interaction of Polymers and Vapors.

Rowen, John W.; Simha, Robert

doi:10.1021/j150471a019

Cited by 39 publications

(13 citation statements)

References 18 publications

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“…As pointed out already by Rowen and Simha, Δ H ( el ) was estimated to be too small for polymers and proteins at room temperature to have any significant effect on sorption isotherms [25]. This is consistent with the largely temperature-independent water sorption isotherms above room temperature [6].…”

Section: Resultssupporting

confidence: 77%

“…It was suggested that the system at the upswing could be treated as a very concentrated solution based on the Flory-Huggins theory [6, 25]. The Flory-Huggins theory describes the mixing of water with protein by a three-dimensional lattice model, where a protein molecule is represented by a chain occupying x lattice cells and each water molecule occupies one lattice cell [26].…”

Section: Resultsmentioning

confidence: 99%

“…Δ S m =− k B [ N 1 ln v 1 + N 2 ln v 2 ] is the entropy of mixing where v 1 = N 1 /( N 1 + xN 2 ) and v 2 = xN 2 /( N 1 + xN 2 ) are the volume fractions of water and proteins, respectively.

Δ H_{(e l)} = V \cdot (K / 2) {(v_{2}^{- 1 / 3} - 1)}^{2}

is the elastic energy, as approximated to the first order, due to the volume expansion upon water addition as given by Rowen and Simha [25], where V = V̄ 1 ( N 1 + xN 2 ) is the total volume of the N 2 protein molecules mixed with N 1 water molecules and V̄ 1 is the volume of each lattice cell. K is the macroscopic parameter of the elastic modulus of the proteins.…”

Section: Resultsmentioning

confidence: 99%

“…This correction is not necessary in Δ H ( el ) since the elastic energy depends on the volume change of the bulk. The equality of the chemical potentials of water in the vapor phase, μ vapor = k B T ln( P / P 0 ), and in the water-protein mixture leads to [25, 28, 29]…”

Section: Resultsmentioning

confidence: 99%

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Temperature dependence of lysozyme hydration and the role of elastic energy

et al. 2011

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Water plays critical roles in protein dynamics and functions. However, the most basic property of hydration—the water sorption isotherm—remains inadequately understood. Surface adsorption is the commonly adopted picture of hydration. Since it does not account for changes in the conformational entropy of proteins, it is difficult to explain why protein dynamics and activity change upon hydration. The solution picture of hydration provides an alternative approach to describe the thermodynamics of hydration. Here, the flexibility of proteins could influence the hydration level through the change of elastic energy upon hydration. Using nuclear magnetic resonance to measure the isotherms of lysozyme in situ between 18 and 2°C, the present work provides evidence that the part of water uptake associated with the onset of protein function is significantly reduced below 8°C. Quantitative analysis shows that such reduction is directly related to the reduction of protein flexibility and enhanced cost in elastic energy upon hydration at lower temperature. The elastic property derived from the water isotherm agrees with direct mechanical measurements, providing independent support for the solution model. This result also implies that water adsorption at charged and polar groups occurring at low vapor pressure, which is known for softening the protein, is crucial for the later stage of water uptake, leading to the activation of protein dynamics. The present work sheds light on the mutual influence of protein flexibility and hydration, providing the basis for understanding the role of hydration on protein dynamics.

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Section: Resultssupporting

confidence: 77%

Section: Resultsmentioning

confidence: 99%

“…Δ S m =− k B [ N 1 ln v 1 + N 2 ln v 2 ] is the entropy of mixing where v 1 = N 1 /( N 1 + xN 2 ) and v 2 = xN 2 /( N 1 + xN 2 ) are the volume fractions of water and proteins, respectively.

Δ H_{(e l)} = V \cdot (K / 2) {(v_{2}^{- 1 / 3} - 1)}^{2}

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

See 2 more Smart Citations

Temperature dependence of lysozyme hydration and the role of elastic energy

et al. 2011

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show abstract

“…error12 has been corrected in the kinetic energy contribution, which is to be expressed in terms of the individual masses of the constituents and not of the mean mass SmT. We note that this error does not a †ect earlier applications, but becomes signiÐcant here in view of eqn (2). Note that eqn (8) includes only translational kinetic terms.…”

Section: Theorymentioning

confidence: 99%