Hydrophobic hydration and hydrophobic interaction in aqueous solutions of tert-butyl alcohol and trimethylamine-N-oxide: a correlation with the effect of these two solutes on the micellization process

Freda, M.; Onori, G.; Santucci, A.

doi:10.1039/b203773d

Cited by 38 publications

(87 citation statements)

References 21 publications

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“…1 For TMAO samples, this band maintains the characteristic typical of a monomeric solute dispersion (no variation in frequency or in other parameters). 3 This result substantially agrees with the roughly linear trends in ∆ versus X 2 , as reported in Figures 6 and 7. In contrast, the CH stretching frequency in the TBA case is constant for X 2 < 0.025, decreases rapidly in the range of 0.025 < X 2 < 0.13, and for higher X 2 progressively saturates toward the pure-alcohol value.…”

Section: Resultssupporting

confidence: 91%

“…40 For example, the critical micelle concentration (cmc) of sodium dodecyl sulfate (SDS) in the presence of TBA decreases at low alcohol mole fractions and increases at high alcohol concentrations, passing through a minimum at X 2 ≈ 0.025, where the hydrophobic clustering of TBA molecules starts. 3 Furthermore, in the same concentration range where the cmc and thus the free energy of micellization show a minimum, a maximum is observed for the transition enthalpy and entropy in the case of lysozyme thermal denaturation in H 2 O/TBA mixtures. 21 Thus, the stabilization of both the protein and the micellar structures in the H 2 O/TBA mixtures appears to be closely linked to the properties and the anomalous behavior of the mixed solvent.…”

Section: From Eqs 3 and 4 One Obtainsmentioning

confidence: 91%

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Hydrogen Bonding of Water in Aqueous Solutions of Trimethylamine-N-oxide and tert-Butyl Alcohol: A Near-Infrared Spectroscopy Study

et al. 2004

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The hydration properties of two biologically relevant molecules, trimethylamine-N-oxide (TMAO) and tertbutyl alcohol (TBA), were investigated by monitoring the effects of these two solutes on the near-infrared (NIR) spectra of water. In particular, the 1450-nm ν 1 + ν 3 water combination band (ν 1 is the symmetric stretching and ν 3 is the asymmetric stretching) and the 1928-nm ν 2 + ν 3 band (ν 2 is the bending) were recorded at 25°C in aqueous solutions of TBA and TMAO over the 0-0.1 and 0-0.05 solute mole fraction intervals for TBA and TMAO, respectively. NIR data show, in agreement with molecular dynamics simulations and other suggestions found in the literature, that on the whole water molecules are more tightly coordinated by TMAO than by TBA. Furthermore, nonadditive perturbations of the water's H-bond network are observed for TBA and are absent in the TMAO case. These results are discussed in connection to the significantly different action exerted by these two solutes on typical processes governed by hydrophobic interactions, such as protein folding and micellization of a surfactant. In these processes, the data support the assumption that the presence of TMAO or TBA modifies the extent of the free-energy contribution associated with structural reorganization of water.

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Section: Resultssupporting

confidence: 91%

Section: From Eqs 3 and 4 One Obtainsmentioning

confidence: 91%

Hydrogen Bonding of Water in Aqueous Solutions of Trimethylamine-N-oxide and tert-Butyl Alcohol: A Near-Infrared Spectroscopy Study

et al. 2004

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“…In particular, the latter exhibits a rather steep decrease in the 0.02-0.03 solute molar fraction range, that is in the same concentration range where remarkable changes in a number of physical properties have been experimentally shown to occur for aqueous solutions of TBA but not for those of TMAO. 10 These experimental findings were interpreted as indicating that in the above concentration range TBA starts to self-aggregate while TMAO apparently does not selfaggregate up to the highest concentration considered (i.e., X 2 ¼ 0.05). 9 Moreover, analogous data for aqueous solutions of GB represented in Fig.…”

Section: Resultsmentioning

confidence: 99%

Molecular dynamics simulation of aqueous solutions of trimethylamine-N-oxide and tert-butyl alcohol

Fornili

Civera

Sironi

et al. 2003

Phys. Chem. Chem. Phys.

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In this work we have investigated hydration properties of aqueous solutions up to a solute molar fraction X 2 ¼ 0.125 of two isosteric molecules -the bioprotectant trimethylamine-N-oxide (TMAO) and the denaturant tert-butyl alcohol (TBA) -using molecular dynamics simulation at 298 K. Statistical analyses of the trajectories show in particular that as the solute concentration increases the number of the water molecules in the first hydration shell decreases uniformly for TMAO, while for TBA it decreases more rapidly in a concentration range where experiments indicate that TBA starts to self-aggregate. No appreciable solute segregation occurs for TMAO even in the most concentrated solution, where on the average each water molecule is shared by two solutes. This result parallels what has been recently found for glycine betaine, an organic osmolyte closely related to TMAO.

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“…However, no clear mechanism for the conjectured osmolyte activity with the backbone has been devised. Recent work has argued that the presence of osmolyte alters protein stability indirectly by affecting the water structure,23–25 whereas a case has been made that it is the direct interaction, or lack of, between the osmolyte and backbone that causes the osmolyte effect 26–28…”

Section: Introductionmentioning

confidence: 99%

TrimethylamineN‐oxide influence on the backbone of proteins: An oligoglycine model

et al. 2009

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The study of organic osmolytes has been pivotal in demonstrating the role of solvent effects on the protein backbone in the folding process. Whereas a thermodynamic description of the interactions between the protein backbone and osmolyte has been well defined, the structural analysis of the effect of osmolyte on the protein backbone has been incomplete. Therefore, we have carried out simulations of a peptide backbone model, glycine 15 in protecting osmolyte TMAO solution in order to determine the effect of the solution structure on the conformation of the peptide backbone. We demonstrate that the models chosen show that the ensemble of backbone structures shifts towards a more collapsed state in TMAO solution as compared to pure water solution. The collapse is consistent with preferential exclusion of the osmolyte caused by unfavorable interactions between osmolyte and peptide backbone. The exclusion is due to strong triplet correlations of osmolyte, water, and peptide backbone. This provides a clear mechanism demonstrating that even a modest concentration of TMAO forces the protein backbone to adopt a more collapsed structure in the absence of sidechain effects.

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Hydrophobic hydration and hydrophobic interaction in aqueous solutions of tert-butyl alcohol and trimethylamine-N-oxide: a correlation with the effect of these two solutes on the micellization process

Cited by 38 publications

References 21 publications

Hydrogen Bonding of Water in Aqueous Solutions of Trimethylamine-N-oxide and tert-Butyl Alcohol: A Near-Infrared Spectroscopy Study

Hydrogen Bonding of Water in Aqueous Solutions of Trimethylamine-N-oxide and tert-Butyl Alcohol: A Near-Infrared Spectroscopy Study

Molecular dynamics simulation of aqueous solutions of trimethylamine-N-oxide and tert-butyl alcohol

TrimethylamineN‐oxide influence on the backbone of proteins: An oligoglycine model

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