STUDY OF COMPLEX FORMATION OF Co(II) WITH TRIGLYCINE IN AQUEOUS SOLUTION

Peptides are an extensive class of both natural and synthetic organic compounds, many of which have high and diverse physiological activity. The relevance of the study of the complexing properties of tripeptides is determined by the large value of these compounds in biological processes, since peptides are a simplified fragment of proteins and are widely used in various sectors of the pharmaceutical industry. One of the representatives of low molecular weight tripeptides is glycyl-glycyl-glycine. In this work, the complex formation of trigl . ycine with Co2+ ions at 298.15 K and I = 0.2 mol/l (KNO3) was studied by potentiometric titration. The study of the complexing properties of triglycine with Co2+ was carried out by the method of potentiometric titration with the ratios M:L = 1:1, 1:2, 1:5. For processing the experimental data, the universal program PHMETR was used, designed to calculate equilibrium constants with an arbitrary number of reactions from the measured equilibrium concentration of one of the particles. The existence of CoL, CoH-1L, CoL2CoH2L22-, CoL3-, CoH-3L34- complexes was established. Their stability constants were determined. And the probable structures of the resulting complexes were proposed. The results of this study show that the oxygen and nitrogen atoms of the peptide group are involved in the processes of interaction between Co(II) and triglycine. This significantly changes the thermodynamics of the complex formation of short peptides in comparison with amino acids. The stability constants of cobalt (II) triglycinates obtained in this work allow one to carry out mathematical modeling of equilibria in multicomponent solutions, to predict the behavior of systems in a wide range of concentrations and pH. They can form the basis for generalizations concerning the structure and behavior of low molecular weight peptides in solution, and used for further studies, including calorimetric ones.