FIG. 4.

Membrane permeabilization of L. donovani promastigotes by α1-acylated CA(1-7)M(2-9) analogues. Parasites were incubated with peptides by the standard assay in the presence of the corresponding fluorescent probe. (A) Increase in 2 μM SYTOX green fluorescence by interaction with internal nucleic acids after membrane permeabilization by the peptides. Excitation and emission wavelengths were 485 and 520 nm, respectively. (B) Collapse of plasma membrane potential by acylated peptides as measured by increase in 0.2 μM bisoxonol fluorescence. Excitation and emission wavelengths were 544 and 584 nm, respectively. Symbols: ●, CA(1-7)M(2-9); □, Ac^α1-CA(1-7)M(2-9); ♦, Oct^α1-CA(1-7)M(2-9); ▵, Lau^α1-CA(1-7)M(2-9); ▾, Myr^α1-CA(1-7)M(2-9). Values obtained with 5 μM CA(1-8)M(1-18) (●), 0.05% Triton X-100 (▪), and 0.5 μM valinomycin (○) are shown for comparison. Data are expressed as means ± standard deviations.