Temperature Dependence of Soret Coefficient in Aqueous and Nonaqueous Solutions of Pullulan

Kishikawa, Yuki; Wiegand, Simone; Kita, R.

doi:10.1021/bm9013149

Cited by 43 publications

(49 citation statements)

References 56 publications

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“…The increase in the magnitude of the Soret coefficient with temperature has been correlated with the breaking of hydrogen bonds, since the latter is more favourable at high temperature. The temperature dependence of S T can be modelled with an empirical equation proposed by Iacopini and Piazza 26 , which fits accurately the behaviour observed in biological systems 27 , aqueous solutions and suspensions. However, deviations from this temperature dependence have been reported in other aqueous solutions such as ethanol 28 , ethylen glycol oligomers 29 , or formamide at high concentration 30 .…”

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confidence: 68%

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Unravelling the hydrophobicity of urea in water using thermodiffusion: implications for protein denaturation

Niether

Lecce

Bresme

et al. 2018

Phys. Chem. Chem. Phys.

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Urea is widely used as a protein denaturant in aqueous solutions. Experimental and computer simulation studies have shown that it dissolves in water almost ideally at high concentrations, introducing little disruption in the water hydrogen bonded structure. However, at concentrations of the order of 5 M or higher, urea induces denaturation in a wide range of proteins. The origin of this behaviour is not completely understood, but it is believed to stem from a balance between urea-protein and urea-water interactions, with urea becoming possibly hydrophobic at a specific concentration range. The small changes observed in the water structure make it difficult to connect the denaturation effects to the solvation properties. Here we show that the exquisite sensitivity of thermodiffusion to solute-water interactions allows the identification of the onset of hydrophobicity of urea-water mixtures. The hydrophobic behaviour is reflected in a sign reversal of the temperature dependent slope of the Soret coefficient, which is observed, both in experiments and non-equilibrium computer simulations at ∼5 M concentration of urea in water. This concentration regime corresponds to the one where abrupt changes in the denaturation of proteins are commonly observed. We show that the onset of hydrophobicity is intrinsically connected to the urea-water interactions. Our results allow us to identify correlations between the Soret coefficient and the partition coefficient, log P, hence establishing the thermodiffusion technique as a powerful approach to study hydrophobicity.

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confidence: 68%

“…S T = 0. Equation (2) describes accurately the thermodiffusion of macromolecules in dilute aqueous solutions 26,27,47 , but fails with low-molecular-weight mixtures, usually at high concentrations 30 , and also in the dilute regime for specific systems, such as ethanol/water 28 .…”

Section: Theoretical Background Of Thermophoresismentioning

confidence: 99%

Unravelling the hydrophobicity of urea in water using thermodiffusion: implications for protein denaturation

Niether

Lecce

Bresme

et al. 2018

Phys. Chem. Chem. Phys.

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“…TDFRS has been employed to study Soret effect in liquid mixtures of hydrocarbons [99,110,111], polymers [28,112e115], biopolymers [116], ferrofluids [117,118], colloids [119] aqueous [64,120,121] as well as non-aqueous solutions [116,122].…”

Section: Thermal Diffusion Forced Rayleigh Scattering (Tdfrs)mentioning

confidence: 99%

Experimental approaches to study thermodiffusion – A review

Srinivasan

Saghir

2011

International Journal of Thermal Sciences

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“…TDFRS has been widely used to determine Soret coefficients in polymers and colloids. [31][32][33] Nonetheless, in conventional TDFRS the use of an additive is required to absorb heat in order to increase the temperature of the sample, resulting in an undesired contamination that might affect the transport properties of the species of interest. Therefore, to avoid the drawbacks of using a third component, techniques with in situ optical detection coupled with a boundary temperature control system have been developed, e.g., OBD 13 and interferometric techniques.…”

Section: Introductionmentioning

confidence: 99%

Measurement of Soret and Fickian diffusion coefficients by orthogonal phase-shifting interferometry and its application to protein aqueous solutions

Torres

Komiya

Henry

et al. 2013

The Journal of Chemical Physics

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We have developed a method to measure thermodiffusion and Fickian diffusion in transparent binary solutions. The measuring instrument consists of two orthogonally aligned phase-shifting interferometers coupled with a single rotating polarizer. This high-resolution interferometer, initially developed to measure isothermal diffusion coefficients in liquid systems [J. F. Torres, A. Komiya, E. Shoji, J. Okajima, and S. Maruyama, Opt. Lasers Eng. 50, 1287 (2012)], was modified to measure transient concentration profiles in binary solutions subject to a linear temperature gradient. A convectionless thermodiffusion field was created in a binary solution sample that is placed inside a Soret cell. This cell consists of a parallelepiped cavity with a horizontal cross-section area of 10 × 20 mm(2), a variable height of 1-2 mm, and transparent lateral walls. The small height of the cell reduces the volume of the sample, shortens the measurement time, and increases the hydrodynamic stability of the system. An additional free diffusion experiment with the same optical apparatus provides the so-called contrast factors that relate the unwrapped phase and concentration gradients, i.e., the measurement technique is independent and robust. The Soret coefficient is determined from the concentration and temperature differences between the upper and lower boundaries measured by the interferometer and thermocouples, respectively. The Fickian diffusion coefficient is obtained by fitting a numerical solution to the experimental concentration profile. The method is validated through the measurement of thermodiffusion in the well-known liquid pairs of ethanol-water (ethanol 39.12 wt.%) and isobutylbenzene-dodecane (50.0 wt.%). The obtained coefficients agree with the literature values within 5.0%. Finally, the developed technique is applied to visualize biomolecular thermophoresis. Two protein aqueous solutions at 3 mg∕ml were used as samples: aprotinin (6.5 kDa)-water and lysozyme (14.3 kDa)-water. It was found that the former protein molecules are thermophilic and the latter thermophobic. In contrast to previously reported methods, this technique is suitable for both short time and negative Soret coefficient measurements.

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Temperature Dependence of Soret Coefficient in Aqueous and Nonaqueous Solutions of Pullulan

Cited by 43 publications

References 56 publications

Unravelling the hydrophobicity of urea in water using thermodiffusion: implications for protein denaturation

Unravelling the hydrophobicity of urea in water using thermodiffusion: implications for protein denaturation

Experimental approaches to study thermodiffusion – A review

Measurement of Soret and Fickian diffusion coefficients by orthogonal phase-shifting interferometry and its application to protein aqueous solutions

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