Scientific supervisor: Vladimir P. Barannikov, Doctor of Chemical Sciences, Senior Researcher, Head of Laboratory at ISC RAS.
Official opponents:
Supervising organization: Ivanovo State University of Chemistry and Technology.
Abstract
The work is aimed at solving a current scientific problem of establishing regularities in how the structure and ion state of dipeptides affect the characteristics of their interaction with anionic micelles and configuration of the resulting complexes, which is important for the development of physical chemistry of solutions of biologically active compounds.
The research expands the understanding of the mechanism of interaction between anionic micelles of sodium dodecyl sulfate and a variety of ionic forms of dipeptides containing additional hydrophilic charged side groups or hydrophobic alkyl groups of different length and branching. The results are confirmed by experimental studies and computer simulation data. The researcher has also identified the regularities of the influence of the interactions on binding with an anionic micelle: ionic form, dipeptide structure, and nature of additional side groups (presence or absence of hydrophilic and hydrophobic side groups and their branching).
Theoretical significance of the study
The author has proven the existence of hydrogen bonds between peptides and head groups of micelles and evaluated the average number of the bonds formed, the influence of branching of amino acid radicals and the number of reaction sites on the orientation in micelles of peptides with the same charge. She has also shown that on the surface of anionic micelles the dipeptides are localized inside the double electric layer.
A complex of experimental research methods has been used in the work, including solution calorimetry, dynamic light scattering and NMR, as well as quantum chemical calculations and molecular dynamics simulation. New results have been obtained concerning the effect of concentration, ion state, and structure of peptides on the enthalpy of interaction with sodium dodecyl sulfate micelles, their averaged diameters and zeta-potentials, the influence of electrostatic forces, hydrogen bonding, hydrophobic effect, and nature of side groups on the binding of dipeptides with anionic micelles and the structure of the micellar complexes formed.
Practical significance of the study
The author has developed an experimental procedure for studying peptide-micelle interactions based on maintaining a constant concentration of surfactants and varying the peptide concentration. The procedure makes it possible to determine the interaction characteristics excluding the overlapping of micelle restructuring due to the changes in surfactant concentration. The new quantitative characteristics determined by the researcher allowed her to identify regularities in the interaction between peptides of different structures and anionic micelles of sodium dodecyl sulfate: enthalpies of interaction unaffected by micelle restructuring with changes in the surfactant concentration, averaged diameters and zeta-potentials of micelles in the presence of peptides; the most stable configurations of complexes comprised of a fragment of an anionic micelle of sodium dodecyl sulfate and peptides of different structures, position and orientation of zwitter-ions and multipole ionic species of dipeptides bound to the anionic micelle. In addition, the researcher has presented possible areas of application of the study results for modeling interactions of pharmacologically active dipeptides of aliphatic and carnosine series with biological membranes and developing new compositions for food and cosmetic products.
