Can trimethylamine-N-oxide act to influence the self-aggregation of tert-butyl alcohol?

Abstract

We report classical molecular dynamics simulation studies of aqueous solution consisting of water, tert-butyl alcohol (TBA) and trimethylamine-N-oxide (TMAO). In spite of the fact that both TBA and TMAO molecules have very similar geometry with hydrophobic and hydrophilic groups, they behave very differently in aqueous solutions. Our aim is to see the role of TMAO on the self-aggregation (or association) of TBA molecules. We observe that, TMAO acts to postpone the aggregation of TBA molecules (takes place via the hydrophobic ends) to some extent. Addition of 0.10 mole fraction of TMAO shifts the aggregation concentration of TBA from x tba = 0.025 to x tba = 0.06. From the excess coordination number, calculation it is noticed that up to x tba = 0.06, TBA molecules are favourably solvated by TMAO by replacing water molecules from TBA solvation shell but above this concentration, TBA-TMAO interaction decreases. This is further confirmed by water-TMAO interactions which shows a shift above x tba = 0.06 indicating more preferred interactions between them. We also observe a noticeable increase in the water-water hydrogen bond life time in presence of TBA molecules indicating more structuring of water molecules.

Inclusion of Theobromine Modifies Uric Acid Aggregation with Possible Changes in Melamine–Uric Acid Clusters Responsible for Kidney Stones

“…A measurement of how many molecules of a specific solute or solvent accumulate around a reference solute is the first shell coordination number (CN) . CN can be described by the use of the equation as follows: − This equation defines the CN of atoms of type β in a solvation shell around the atomic sites of type α from 0 to separation r c . ρ β depicts the number density of atom type β in the system.…”

How Different Are the Characteristics of Aqueous Solutions of tert-Butyl Alcohol and Trimethylamine-N-Oxide? A Molecular Dynamics Simulation Study

“…However, their action toward protein structure and stability and their behavior in aqueous solutions are markedly different. It is well known through experiments and simulations that TBA forms aggregates in its aqueous solution at a very moderate concentration, whereas TMAO does not. − It is also known that addition of TBA into water causes the density of the solution to decrease, whereas on addition of TMAO, the density of the solution increases. Most likely, as a consequence of these disparate behaviors, TBA acts as a denaturant favoring the unfolded structure of a protein, whereas TMAO stabilizes native structure of a protein and effectively counteracts denaturation arising from chemical denaturant or elevated pressure/temperature.…”

“…Given the dispute over exact molecular characteristics of the TBA–water and TMAO–water solutions, it is expected that the atomistic computer simulation, which easily explores any system with atomistic resolution, will be able to resolve the problem decisively. In fact, several simulation studies − ,− have been performed to gain molecular level insight into the structure, aggregation behavior, and dynamics of these two aqueous solutions. Patey and co-workers tried to figure out the origin of such differences in behavior in these two solutions.…”

Structure and Orientation of Water and Choline Chloride Molecules around a Methane Hydrophobe: A Computer Simulation Study

“…The box dimension is chosen in such a way that there is a sufficient gap between the methane molecule, at the center and the edges of the box to avoid self-interaction across the periodic images [43] and similar box sizes have been used previously to study similar kinds of system. [44,45] Then, we keep a methane molecule at the center of the simulation box and gradually add the adequate numbers of choline and chloride ions as per the requirement to produce 1-4 M ChCl concentrations by using the random insertion module (gmx_insert) of GROMACS. [46] The remaining volume is filled with water molecules using the gmx_solvation module of GROMACS.…”