Study of solute–solute and solute–solvent interactions of l-threonine in aqueous-glucose solutions at different temperatures by using volumetric and viscometric methods

Densities, ρ of solutions of l-threonine in water and in aqueous-glucose solvents (5, 10, 15 and 20% of glucose, w/w in water) at T = (293.15, 298.15, 303.15, 308.15, 313.15 and 318.15) K and viscosities, η of these solutions at (298.15, 303.15, 308.15, 313.15 and 318.15) K were measured at atmospheric pressure. From these experimental results, the apparent molar volume, VϕVϕ, limiting apparent molar volume, Vϕ∘ and the slope, Sv  , transfer volume, Vϕ,tr∘, Falkenhagen coefficient, A, Jones–Dole coefficient, B, temperature derivative of B-coefficients, dB/dT  , Gibbs free energies of activation of viscous flow per mole of solvent, Δμ1∘# and per mole of solute, Δμ2∘# and hydration number, Hn were calculated. The results are interpreted in terms of solute–solvent and solute–solute interactions in these systems. It has been observed that there exist strong solute–solvent interactions in these systems, which increase with increase in glucose concentration. It is also observed that l-threonine acts as structure-breaker in these aqueous-glucose solvents. The thermodynamics of viscous flow are also discussed.

► The study reports interactions of l-threonine with glucose in aqueous media. ► Provides data to estimate physicochemical properties of proteins in these media. ► Provides better understanding biological phenomena involving l-threonine. ► Correlates physicochemical properties of l-threonine with its behaviour in solution.