Thermochemical Analysis of the Interaction between Pyridoxine and L-Carnosine, L-Histidine, and L-Asparagine in Aqueous Solutions

Abstract

Calorimetry is used to study the interaction between dipeptide L-carnosine (Car) and amino acids L-histidine (His) and L-asparagine (Asn) with pyridoxine (PN) in an aqueous solution. Experimental values of the enthalpy of dissolution of amino acids and peptide in an aqueous PN solution at T = 298.15 K are obtained for the first time. The thermodynamic characteristics and stoichiometry of the formation of molecular complexes between the reactants are determined. It is found that the stability of the resulting complexes depends on the structure of the reactants and falls in the order Car Asn His. It is shown that the main contribution to the stabilization of the resulting complexes comes from the entropy component of the Gibbs energy of complexation.