The effect of the side chain structures on the energy of intermolecular interactions of α-amino acids with some formamides in aqueous solutions at T = 298.15 K

Abstract

To evaluate the effect of amino acid side chains on the thermodynamics of their interaction with the formamides molecules in aqueous solutions, we expanded the range of amino acids by studying in the present investigation the thermodynamics of the dissolution of glutamine in mixed solvents {water + (formamide, N‑methylformamide and N,N‑dimethylformamide)} at T = 298.15 K and organic solvent mole fractions up to x2 ~ 0.3. The standard enthalpies of solution (ΔsolH°) and transfer (ΔtrH°) of l-glutamine from water to a mixed solvent as well as the enthalpy coefficients of pairwise interactions (hxy) were calculated. The interrelation between enthalpic characteristics of l-glutamine dissolution (transfer) and the composition of water-organic mixtures was determined. Using the enthalpic coefficients of pairwise interactions of l-glutamine and five more amino acids (glycine, dl-α-alanine, l-valine, l-methionine, and l-threonine), the enthalpic contributions of the side chains of these amino acids to their interparticle interactions with the molecules of formamides were calculated.