Tetrapeptide Lys-Glu-Asp-Trp is a mimetic of insulinotropic peptides and reduces the blood glucose level. This tetrapeptide increases the content of important factors of differentiation in endocrine pancreatic cells in vitro. Molecular modeling shows that this tetrapeptide can interact with not only minor, but also major groove of DNA molecule. The interaction with the major groove is more specific, because it depends on the primary sequences of the tetrapeptide and DNA. Sequence GGCAG is the putative binding site for the tetrapeptide.