Niether, Doreen ORCID: 0000-0002-8496-4215, Di Lecce, Silvia, Bresme, Fernando and Wiegand, Simone (2018). Unravelling the hydrophobicity of urea in water using thermodiffusion: implications for protein denaturation. Phys. Chem. Chem. Phys., 20 (2). S. 1012 - 1021. CAMBRIDGE: ROYAL SOC CHEMISTRY. ISSN 1463-9084

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Abstract

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 similar to 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, logP, hence establishing the thermodiffusion technique as a powerful approach to study hydrophobicity.

Item Type: Journal Article
Creators:
CreatorsEmailORCIDORCID Put Code
Niether, DoreenUNSPECIFIEDorcid.org/0000-0002-8496-4215UNSPECIFIED
Di Lecce, SilviaUNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Bresme, FernandoUNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Wiegand, SimoneUNSPECIFIEDUNSPECIFIEDUNSPECIFIED
URN: urn:nbn:de:hbz:38-198894
DOI: 10.1039/c7cp05843h
Journal or Publication Title: Phys. Chem. Chem. Phys.
Volume: 20
Number: 2
Page Range: S. 1012 - 1021
Date: 2018
Publisher: ROYAL SOC CHEMISTRY
Place of Publication: CAMBRIDGE
ISSN: 1463-9084
Language: English
Faculty: Unspecified
Divisions: Unspecified
Subjects: no entry
Uncontrolled Keywords:
KeywordsLanguage
MOLECULAR-DYNAMICS SIMULATION; THERMAL-DIFFUSION; SORET COEFFICIENT; AQUEOUS-SOLUTIONS; TEMPERATURE-DEPENDENCE; DIELECTRIC-RELAXATION; THERMOPHORESIS; SPECTROSCOPY; TRANSPORT; MIXTURESMultiple languages
Chemistry, Physical; Physics, Atomic, Molecular & ChemicalMultiple languages
Refereed: Yes
URI: http://kups.ub.uni-koeln.de/id/eprint/19889

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