title: An X-ray and neutron scattering study of the equilibrium between trimethylamine N-oxide and urea in aqueous solution.
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.
authors: Department of Chemistry, Katholieke Universiteit Leuven, Celestijnenlaan 200F, B-3001 Leuven, Belgium. Filip.Meersman@chem.kuleuven.be
authors: Filip
authors: F
authors: Meersman
authors: Daniel
authors: D
authors: Bowron
authors: Alan K
authors: AK
authors: Soper
authors: Michel H J
authors: MH
authors: Koch
mesh_terms: D008744:Methylamines / Q000737:chemistry*; D033363:Neutron Diffraction; D010087:Oxides / Q000737:chemistry*; D011485:Protein Binding; D011506:Proteins / Q000737:chemistry; D012542:Scattering, Radiation; D053838:Scattering, Small Angle; D014508:Urea / Q000737:chemistry*; D014867:Water / Q000737:chemistry; D014961:X-Ray Diffraction
chemical_list: D008744:Methylamines; D010087:Oxides; D011506:Proteins; D014867:Water; D014508:Urea; C005855:trimethyloxamine