Formation processes of coordination compounds in the system tryptophan - physiological solution

The present work is devoted to study of processes of protolytic dissociation of tryptophan at a temperature of 293.16 K, the ionic strength of 0.1 mol/l solution in physiological solution by means of ph-metric titration method. For the first time, using experimental data, modeling the dissociation process and computer programs, the dissociation constants of protonated, ionic forms with formation of tryptophan anion were determined. These values slightly differ from the corresponding constants in an aqueous solution, which is associated with the influence of sodium and chloride ions on solvation processes. The complex formation processes in tryptophan-physiological solution system were studied at temperature of 293.16 K, the ionic strength of solution was 0.1 mol/l, as well as various concentration parameters by the method of ph-meter. It was found that the complex formation process in the system proceeds in a wide range of ph from 0.8 to 14.0. With the help of a computer program, the compositions of complexes being formed were determined. The constants of complexes formation were calculated. The mole fractions of the complexes were determined and their distribution diagrams were plotted. It was shown that all four complexes have a maximum accumulation rate of over 99% and dominate in a wide range (from 4 to 9 ph units). Such model parameters make the synthesis of complexes and their isolation from solution quite feasible. (author)