Design And Study Of Membrane Active Peptides And Biological Activities Based On Hydrophobicity And Helicity

Membrane active peptides(MAPs)are a class of bioactive peptides that target cell membranes because they have the ability to disrupt bacterial cell membranes and resist bacterial resistance,and are considered candidates for new broad-spectrum antimicrobial agents.It is important to study the structure-activity relationship of membrane active peptides and the interaction process with cell membrane,which is of great significance to the design and modification of membrane active peptides.In the previous study,we have demonstrated that the amphipathic ?-helix peptide V13K(Ac-KWKSFLKTFKSAKKTVLHTALKAISS-amide)exhibits significant antibacterial activity and anticancer activity and produces only weak hemolytic activity against human hematopoietic cells.In this study,we selected V13 K as a framework,with D-type amino acid on its amphiphilic spiral structure of the polar and non-polar surface of the L-type amino acid for single and multi-point substitution,and then to study the helicity and hydrophobicity on peptide biological activity.First,the helicity of the parent peptide V13 K and its derived peptides was measured by CD spectroscopy,and the helicity and hydrophobicity of the peptides were confirmed to be related to the number of substitutions of the D-type amino acids in the peptide sequence.Secondly,the biological activity of the designed peptides was studied.In the antimicrobial activity,we evaluated the antibacterial activity and cytotoxicity by MIC and MHC experiments respectively.The penetration of the peptide on the outer membrane and inner membrane of the E.coli was determined by NPN and ONPG experiments,respectively.In anticancer activity,we used four cancer cells(HeLa,MIA PaCa-2,HPAC and BxPC-3)as representative,and evaluated the anticancer activity by MTT assay.The results showed that the antibacterial and anticancer activity of the peptide was positively correlated with the helicity and hydrophobicity.Finally,we studied the interaction between the peptide and the cell membrane.The results of LDH release showed that V13 K exerts its anticancer activity by penetrating and destroying the integrity of cancer cell membrane.V13 K and its derived peptide interact with LUV simulated prokaryotic cell membrane,eukaryotic cell membrane and cancer cell membrane.The Zeta potential of the peptide and LUV mixed system showed that the electrostatic attraction was helpful to the interaction between the peptide and the cell membrane.The substitution of D-type amino acids leads to low hydrophobicity and helicity of peptide derivatives,which in turn affect their anticancer activity and antibacterial activity.These results further suggest that proper modification of membrane active peptides based on helicity and hydrophobicity is of great importance for their biological activity,which is an important guide for the rational design and modification of membrane active peptides.