Calorimetric study of the molecular complex formation of glycyl-glycyl-glycine with 18-crown-6 in aqueous organic solvents.

The influence of water-ethanol (HO-EtOH), water-acetone (HO-MeAc) and waterdimethylsulfoxide (HO-DMSO) solvents on the reaction of the molecular complex formation between ether 18-crown-6 (18C6) and small peptide glycyl-glycyl-glycine (3Gly) has been studied at T = 298.15 K. The thermodynamic parameters for the reaction (log K, Δ G, Δ H, Δ S) were obtained from calorimetric titration experiments carried out by means of the calorimetric system TAM III (TA Instruments, USA). The thermodynamics of the [3Gly18C6] molecular complex formation is discussed in comparison with thermodynamic parameters of complex formation between 18C6 and amino acids in mixed solvents using the sоlvation-thermodynamic approach. [ABSTRACT FROM AUTHOR]