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Updated: May 31, 2026

High-Resolution Neutron Spectroscopy to Study Picosecond-Nanosecond Dynamics of Proteins and Hydration Water
Published on: April 28, 2022
An X-ray and neutron scattering study of the equilibrium between trimethylamine N-oxide and urea in aqueous solution
Filip Meersman1, Daniel Bowron, Alan K Soper
1Department of Chemistry, Katholieke Universiteit Leuven, Celestijnenlaan 200F, B-3001 Leuven, Belgium. Filip.Meersman@chem.kuleuven.be
Abstract:
The interaction of the osmolytes trimethylamine N-oxide (TMAO) and urea in aqueous solutions at 40 °C was investigated by isotopic substitution neutron scattering at a TMAO mole fraction of 0.05 and TMAO/urea concentration ratios of 1 : 2 and 1 : 4. The partial pair distribution functions obtained by the empirical potential structure refinement method are consistent with those obtained previously for similar pure TMAO and 1 : 1 TMAO-urea solutions and indicate that urea progressively replaces the water molecules in the first coordination shell of the TMAO oxygen atom. The apparent association constant for the TMAO : urea complex (K(1)) was calculated to be 0.14 M(-1), which is of the same order as the experimental urea-protein binding constants per site reported in the literature. This confirms that the two osmolytes act independently at least in the physiological range.
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