Fig. 2

Design, physicochemical features and activity of Pol-CP-NH₂ and Ala-scan analogs. a Schematic of the in vitro biological activity experimental design. Briefly, 10⁴ bacterial cells and serially diluted peptides (0–128 μmol L⁻¹) were added to a 96-well plate and incubated at 37 ^oC. One day after the exposure, the solution in each well was measured in a microplate reader (600 nm) to check inhibition of bacteria compared to the untreated controls and presented as heat maps of antimicrobial activities (μmol L⁻¹) against four bacteria strains: E. coli strain BL21, S. aureus strain ATCC12600 and P. aeruginosa strains PA01 and PA14. Assays were performed in three independent replicates and heat map OD₆₀₀ values are the arithmetic mean of the replicates in each condition. b Graph correlating MIC (μmol L⁻¹) averages vs. H and c MIC (μmol L⁻¹) mean vs. μH, where blue boxes represent peptides with lower activity and red boxes show peptides with higher activity compared to the wild-type, in which we can observe ranges of optimal activity in determined intervals of H and μH values. d Bi-dimensional helical wheels representations of the wild-type indicating positions where Ala-substitution decreased (blue arrows) and enhanced activity (red arrows) and three-dimensional representation from molecular modeling showing substitution positions in which the residues are arranged in two defined faces (hydrophobic and hydrophilic)