Аннотация:Polycationic gramicidin A (gA) derivatives were shown to form unselective pores in lipid membranes and facilitate protein translocation into eukaryotic cells, regardless of the position of the polycationic cluster in the amino acid sequence (Stoilova et al. 2008 Biochim.Biophys.Acta 1778:2026). The present work demonstrated that introduction of a charged group near the N-terminus of gA altered its ability to disturb barrier properties of red blood cell membranes. The hemolytic activity of the Lys-substituted peptides essentially
depended on the lysine position in the gA sequence: [Lys2]gA < [Lys5]gA < [Lys1]gA < [Lys3]gA. The Glu-substituted gA derivatives did not cause hemolysis. According to the data
on osmotic protection, one can suggest that the formed pores were heterogeneous in size, as partial protection was attained with sucrose and raffinose, while nearly complete protection
was exerted by PEG2000 and PEG4000 having larger molecular diameter. The osmotic protection was more pronounced at lower peptide concentrations suggesting that the size of the peptide-induced pores depended on the concentration of the peptide. The hemolytic efficacy of the Lys-substituted peptides correlated with their ability to induce leakage of carboxyfluorescein from liposomes.