QUANTUM CHEMICAL SIMULATION OF THE INTERACTION BETWEEN BALENINE AND A SODIUM DODECYL SULFATE DIMER AS AN ANIONIC MICELLE FRAGMENT. INFLUENCE OF THE DIPEPTIDE IONIC STATE

Complexes of sodium dodecyl sulfate dimer (SDS)2 with β-alanyl-3-methyl-L-histidine dipeptide (balenine) in zwitterionic and cationic forms are simulated by the quantum chemical method DFT/B97D using the 6-311++G(3d,3p) basis set. The most stable configurations of these complexes are found. The complexes are shown to be stabilized by electrostatic forces and hydrogen bonds between the peptide and the dimer. Energy changes and hydrogen bond characteristics during complexation are analyzed. It is established that complexes with cationic balenine are more energy preferable. Balenine complexes and complexes formed by the isomeric peptide β-alanyl-1-methyl-L-histidine (anserine) are compared. As far as the formation of H-bonds with the dimer, position 1 of the balenine imidazole ring is more sterically favorable for the NH group than position 3 in the anserine ring. Structural changes in the peptide during the complexation are analyzed.