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

Fornili, Arianna; Civera, Monica; Sironi, Maurizio; Fornili, Sandro L.

doi:10.1039/b308248b

Cited by 71 publications

(116 citation statements)

References 28 publications

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“…The strong hydration of TMAO has been previously demonstrated in both experiments and simulations. [30][31][32][33][34][35] Urea is a nearly ideal solute in aqueous solution (in the molar scale); is smaller and correspondingly shows more modest correlations with water.…”

Section: Resultsmentioning

confidence: 99%

Backbone additivity in the transfer model of protein solvation

et al. 2010

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The transfer model implying additivity of the peptide backbone free energy of transfer is computationally tested. Molecular dynamics simulations are used to determine the extent of change in transfer free energy (DG tr ) with increase in chain length of oligoglycine with capped end groups. Solvation free energies of oligoglycine models of varying lengths in pure water and in the osmolyte solutions, 2M urea and 2M trimethylamine N-oxide (TMAO), were calculated from simulations of all atom models, and DG tr values for peptide backbone transfer from water to the osmolyte solutions were determined. The results show that the transfer free energies change linearly with increasing chain length, demonstrating the principle of additivity, and provide values in reasonable agreement with experiment. The peptide backbone transfer free energy contributions arise from van der Waals interactions in the case of transfer to urea, but from electrostatics on transfer to TMAO solution. The simulations used here allow for the calculation of the solvation and transfer free energy of longer oligoglycine models to be evaluated than is currently possible through experiment. The peptide backbone unit computed transfer free energy of 254 cal/mol/M compares quite favorably with 243 cal/mol/M determined experimentally.

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Section: Resultsmentioning

confidence: 99%

Backbone additivity in the transfer model of protein solvation

et al. 2010

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“…Some of them are hydrogen-bonded to solute (H-B waters comparison, in the lower row of Fig. 1, water SDFs are shown around the bioprotectans glycine betaine (GB) and trimethylamine-N-oxide (TMAO), and the protein denaturant tert-butyl alcohol (TBA), which have been evaluated from previous simulation data [21,22]. As expected, the water oxygen distribution is more relevant in the space regions surrounding the hydrophilic carboxyl, hydroxyl and amino groups.…”

Section: Resultsmentioning

confidence: 99%

“…This interpretation agrees with the average numbers of first-shell waters for one-solute systems (FSWs, i.e., waters within 3.5 Å from solute atoms). Indeed, from [21,22]. The proline hydration as a function of solute molar fraction is shown in Fig.…”

Section: Resultsmentioning

confidence: 99%

Unusual properties of aqueous solutions of l-proline: A molecular dynamics study

Civera

Sironi

Fornili

2005

Chemical Physics Letters

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Aqueous solutions of the bioprotectant proline are simulated for solute molar fractions ranging from 2.0 · 10 À3 to 2.3 · 10 À1. Statistical analyses show that proline affects the water structure more strongly than glycine betaine and trimethylamine-N-oxide, two of the most effective bioprotectants widely diffuse in nature, and as strongly as tert-butyl alcohol, a protein denaturant which at high concentration self-aggregates. No evidence is found, however, that proline self-aggregates as it has been previously suggested to explain experimental findings on concentrated proline solutions. Nevertheless, the behavior of the diffusion coefficients of proline and water vs. solute concentration qualitatively agrees with such results.

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“…At the same time, they also noted structural ordering of the surrounding water structure. Several other simulation studies [44][45][46] revealed the self-association of TBA molecules in their binary mixture. Lee and Vegt [47] proposed a modified force field for TBA in aqueous solution, in order to have a better approximation of the KirkwoodBuff integrals and made detailed analysis of the structural aspects, again asserting the presence of TBA selfaggregates.…”

Section: Introductionmentioning

confidence: 99%

“…Indeed, several simulation studies [42][43][44][45][46][47][48][49][50] have been performed on this important binary mixture, at different concentrations and using different force fields. Early in the 1990's, Tanaka and Nakanishi [42] performed simulations on this system and noted self-aggregation of TBA molecules at mole fraction 0.17.…”

Section: Introductionmentioning

confidence: 99%

Fluctuating micro-heterogeneity in water–tert-butyl alcohol mixtures and lambda-type divergence of the mean cluster size with phase transition-like multiple anomalies

Banerjee

Furtado

Bagchi

2014

The Journal of Chemical Physics

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Water-tert-butyl alcohol (TBA) binary mixture exhibits a large number of thermodynamic and dynamic anomalies. These anomalies are observed at surprisingly low TBA mole fraction, with xTBA ≈ 0.03 − 0.07. We demonstrate here that the origin of the anomalies lies in the local structural changes that occur due to self-aggregation of TBA molecules. We observe a percolation transition of the TBA molecules at xTBA ≈ 0.05. We note that "islands" of TBA clusters form even below this mole fraction, while a large spanning cluster emerges above that mole fraction. At this percolation threshold, we observe a lambda-type divergence in the fluctuation of the size of the largest TBA cluster, reminiscent of a critical point. Alongside, the structure of water is also perturbed, albeit weakly, by the aggregation of TBA molecules. There is a monotonic decrease in the tetrahedral order parameter of water, while the dipole moment correlation shows a weak non-linearity. Interestingly, water molecules themselves exhibit a reverse percolation transition at higher TBA concentration, xTBA ≈ 0.45, where large spanning water clusters now break-up into small clusters. This is accompanied by significant divergence of the fluctuations in the size of largest water cluster. This second transition gives rise to another set of anomalies around. Both the percolation transitions can be regarded as manifestations of Janus effect at small molecular level.

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

Cited by 71 publications

References 28 publications

Backbone additivity in the transfer model of protein solvation

Backbone additivity in the transfer model of protein solvation

Unusual properties of aqueous solutions of l-proline: A molecular dynamics study

Fluctuating micro-heterogeneity in water–tert-butyl alcohol mixtures and lambda-type divergence of the mean cluster size with phase transition-like multiple anomalies

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