RESUMEN
Numerous natural antimicrobial peptides (AMPs) exhibit a cationic amphipathic helical conformation, wherein cationic amino acids, such as lysine and arginine, play pivotal roles in antimicrobial activity by aiding initial attraction to negatively charged bacterial membranes. Expanding on our previous work, which introduced a de novo design of amphipathic helices within cationic heptapeptides using an 'all-hydrocarbon peptide stapling' approach, we investigated the impact of lysine-homologue substitution on helix formation, antimicrobial activity, hemolytic activity, and proteolytic stability of these novel AMPs. Our results demonstrate that substituting lysine with ornithine enhances both the antimicrobial activity and proteolytic stability of the stapled heptapeptide AMP series, while maintaining low hemolytic activity. This finding underscores lysine-homologue substitution as a valuable strategy for optimizing the therapeutic potential of diverse cationic AMPs.
Asunto(s)
Antibacterianos , Péptidos Catiónicos Antimicrobianos , Hemólisis , Lisina , Pruebas de Sensibilidad Microbiana , Lisina/química , Lisina/farmacología , Antibacterianos/farmacología , Antibacterianos/química , Antibacterianos/síntesis química , Hemólisis/efectos de los fármacos , Péptidos Catiónicos Antimicrobianos/química , Péptidos Catiónicos Antimicrobianos/farmacología , Péptidos Catiónicos Antimicrobianos/síntesis química , Relación Estructura-Actividad , Proteolisis/efectos de los fármacos , Humanos , Estructura MolecularRESUMEN
Cecropin A (1-7) is a cationic antimicrobial peptide which contain lots of basic amino acids. To understand the effect of basic amino acids on cecropin A (1-7), analogues CA2, CA3 and CA4 which have more arginine or lysine at the N-terminal or C-terminal were designed and synthesized. The interaction of cecropin A (1-7) and its analogs with DNA was studied using ultraviolet-visible spectroscopy, fluorescence spectroscopy and circular dichroism spectroscopy. Multispectral analysis showed that basic amino acids improved the interaction between the analogues and DNA. The interaction between CA4 and DNA is most pronounced. Fluorescence spectrum indicated that Ksv value of CA4 is 1.19 × 105 L mol-1 compared to original peptide cecropin A (1-7) of 3.73 × 104 L mol-1. The results of antimicrobial experiments with cecropin A (1-7) and its analogues showed that basic amino acids enhanced the antimicrobial effect of the analogues. The antimicrobial activity of CA4 against E. coli was eightfold higher than that of cecropin A (1-7). The importance of basic amino acid in peptides is revealed and provides useful information for subsequent studies of antimicrobial peptides.
