The cell penetrating peptides pVEC and W2-pVEC induce transformation of gel phase domains in phospholipid bilayers without affecting their integrity.

The cell penetrating peptide (CPP) pVEC has been shown to translocate efficiently the plasma membrane of different mammalian cell lines by a receptor-independent mechanism without exhibiting cellular toxicity. This ability renders CPPs of broad interest in cell biology, biotechnology, and drug delivery. To gain insight into the interaction of CPPs with biomembranes, we studied the interaction of pVEC and W2-pVEC, an Ile --> Trp modification of the former, with phase-separated supported phospholipid bilayers (SPB) by atomic force microscopy (AFM).

Interaction of poly(L-lysine)-g-poly(ethylene glycol) with supported phospholipid bilayers.

Interactions between the graft copolymer poly(L-lysine)-g-poly(ethylene glycol), PLL-g-PEG, and two kinds of surface-supported lipidic systems (supported phospholipid bilayers and supported vesicular layers) were investigated by a combination of microscopic and spectroscopic techniques. It was found that the application of the copolymer to zwitterionic or negatively charged supported bilayers in a buffer of low ionic strength led to their decomposition, with the resulting formation of free copolymer-lipid complexes. The same copolymer had no destructive effect on a supported vesicular layer made up of vesicles of identical composition.