Influence of the composition of water-organic mixtures and of organic solvents properties on solvation of glycyl-L-tyrosine at 298.15Â K

Enthalpies of dissolution of glycyl-L-tyrosine in the mixtures of water with methanol (MeOH), ethanol (EtOH), propanol (1-PrOH), 2-propanol (2-PrOH), acetonitrile (AN), 1,4-dioxane (DO),acetone (AN), dimethylsulfoxide (DMSO), formamide (FA), N-methylformamide (NMF), N,N-dimethylformamide (DMF) and N,N-dimethylacetamide (DMA) have been measured at 298.15 K. The standard enthalpies of the solution (ΔsolH∘) and transfer (ΔtrH∘) of glycol-L-tyrosine from water into aqueous solution of organic co-solvents as well as the enthalpy coefficients of pairwise interaction (hxy) have been calculated. The interrelation between the enthalpy characteristics of dissolution (transfer) of glycyl-L-tyrosine and the composition of aqueous organic mixtures was established. Contributions of the organic co-solvent properties (molar volume, cohesion energy density, dipolarity/polarizability, acidity and basicity) to the energy of pairwise interactions were estimated quantitatively by means of a modified Kamlet-Taft equation. Some characteristics of intermolecular interactions of glycyl-L-tyrosine with the molecules of organic co-solvents with the analogous characteristics of glycylglycine and diglycylglycine were compared.