Thermodynamics of the L-tryptophan interaction with glycerol or urea in water at ambient conditions

The enthalpies of dissolution of L-tryptophan (Trp) in mixtures of water with glycerol (Gl) at X-Gl <= 0.1 mol fractions or with urea (U) at X-U <= 0.15 mol fractions have been measured by the calorimetric method at 298.15 K. The enthalpic parameters of pair and triple interactions of L-tryptophan with glycerol or urea in water have been computed at 298.15 K from experimental data on dissolution enthalpies and the solubility data from literature using standard thermodynamic ratios. The results obtained have been discussed in terms of solute-solute interactions and their relation to macromolecules stability. (C) 2021 Elsevier B.V. All rights reserved.