Figure 2.

Conformational changes and cellular uptake of the S4₁₃-PV, reverse NLS and scrambled peptides. (A) The circular dichroism spectra of the peptides were acquired in sodium phosphate buffer, pH 7.0 (dotted lines), or in the presence of negatively charged membranes composed of POPG, at a lipid/peptide ratio of 4 (straight lines). Clear differences in the peptides spectra was observed in the presence of negatively charged vesicles. (B, C) Hela cells were incubated for 30 minutes, at 37 ºC, with 1.0 μM of rhodamine-labelled peptides. (B) Following treatment with trypsin to remove the non-internalized, surface-bound peptides, cells were analyzed by flow cytometry. (C) Live cells were observed by confocal microscopy. Although all peptides have similar physic-chemical properties, the extent of cellular uptake of the S4₁₃-PV and S4₁₃-PV reverse NLS peptides was significantly more efficient than that observed for the scrambled peptide.