No abstract

The enthalpies of solution of L-R-isoleucine, L-R-cysteine, L-R-aspartic acid, and L-R-glutamic acid have been measured in aqueous sodium chloride solutions at 298.15 K. From the obtained experimental results the standard dissolution enthalpies of amino acids in aqueous NaCl solutions have been determined. These data were used to calculate of the heterogeneous enthalpic pair interaction coefficients based on McMillan-Mayer's theory. These values were interpreted in the terms of the hydrophobic or hydrophilic effects of the side chains of amino acids on their interactions with dissociated sodium chloride in water.

Dissolution enthalpies of several natural amino acids (L-α-asparagine, L-α-glutamine, L-α-aspartic acid, L-αglutamic acid, L-α-arginine, L-α-lysine and L-α-histidine) were measured in aqueous solutions of potassium chloride at T = 298.15 K. Based on the resulting data the standard dissolution enthalpy of amino acids in aqueous solutions of potassium chloride have been determined. The standard dissolution enthalpy values were subsequently used to calculate the heterogeneous enthalpic pair interaction coefficients (h A-KCl ) between zwitterions of L-α-amino acids and dissociated potassium chloride in water. Interparticle interactions in system (amino acid + dissociated KCl + water) were interpreted in terms of the hydrophobic -hydrophilic effects of the side chains of the tested encoded amino acids.