Membranotropic activity of optical isomers of the neuropeptide kyotorphin and a cardiotonic agent, suphan

On modeled monolayer phospholipid (formed from azolectin) membranes, we studied the surface activity of optical isomers of a dipeptide, kyotorphin (Tyr-Arg), and a cardiotonic agent, suphan (N-succinyltryptophan potassium salt). It was found that the membranotropic activity of four studied isomers of kyotorphin is distributed in the order: LL>DL≈LD>DD, and two isomers (by tryptophan) of suphan as LL>DL. The data obtained suggest that the primary mechanism underlying binding of kyotorphin and suphan to the plasma membrane can be considered based on interaction of their molecules with the molecules of membrane phospholipids. Binding of molecules of kyotorphin and suphan by the lipid matrix to the plasma membrane and/or their incorporation into the matrix is a result of the above interaction.