Figure 4.
POPE favors binding to lipids and membrane permeabilization by StII1–30. (A) Representative kinetics of StII1–30 binding to a lipid monolayer are shown. (B) Critical pressure induced by StII1–30 on monolayers of different lipid composition is shown. Lines represent the best linear fit of the Δπ as a function of the initial monolayer pressure (πo); r2 > 0.99. The peptide concentration is 1 μM. (C) Representative fluorescence spectra of StII1–30L2W in the presence of increasing amount of SUVs are shown. (D) Increase in the fluorescence intensity of StII1–30 or StII1–30L2W as a function of lipid concentration is shown. F0 and F stand for the fluorescence intensities (at λmax) from the spectra in the absence and the presence of SUVs, respectively. λexc is StII1–30_(Phe14) 251 nm, λexc is StII1–30L2W_(Trp2) 280 nm, and peptide concentration is 20 μM. (E) Representative kinetics of liposomes permeabilization induced by different concentrations of StII1–30 in LUVs are shown. (F) Release of CF from LUVs promoted by different concentrations of StII1–30 after 60 min of assay is shown. The lipid concentration is 10 μM, and the lipid composition is POPC:SM (50:50) or POPC:SM:POPE (50:40:10). Values in (E) and (F) are shown as the mean values and the SD among three replicates. To see this figure in color, go online.