Molecular design, structural analysis and bactericidal activity of derivatives of antimicrobial peptide Buforin Ⅱ

A novel peptide, named BF2-X, was designed based on the structure-activity analysis of an analogue of BuforinⅡ, named BF2-A.  The BF2-X was a hybrid peptide containing the N-terminal residues 5 to 13 of BF2-A and three repeats of the C-terminal regular α-helical motif RLLR, and the residues 8 valine were replaced by leucine.  The results of bioinformatics analysis had showed that compared with BF2-A, the helicity, positive charge, hydrophobicity rate and C-terminal amphipathy of BF2-X had remarkably enhanced.  Both peptides showed a random coil structure in an aqueous solution, while displaying a typical α-helical structure in 50% trifluoroethanol solution (a membrane mimic condition).  BF2-X exhibited higher α-helical contents than BF2-A in hydrophobic environment.  BF2-X displayed potent antimicrobial activities against a broad spectrum of microorganisms.  And BF2-X showed stronger antimicrobial activities against bacteria tested than parent peptide BF2-A.  These results suggest that the α-helical content was directly correlated with the enhanced antibacterial activity.  Both peptides had no hemolytic action on mouse erythrocyte.