Forschungs- & Entwicklungsinformationsdienst der Gemeinschaft - CORDIS

Cationic CPPs do not permeate lipid membranes

We reassessed the highly controversial issue of direct permeation of strongly cationic peptides across negatively charged lipid membranes. The microscopic studies of rhodamine-labeled giant vesicles incubated with carboxyfluorescein-labeled penetratin yielded no evidence of transbilayer movement. We have also exploited isothermal titration calorimetry and intrinsic tryptophan fluorescence spectroscopy to study the thermodynamics of penetratin partitioning into and translocation across unilamellar-vesicle membranes.

A combination of uptake, release, and dilution experiments consistently demonstrated that, at low peptide concentrations, penetratin is not able to cross phospholipid bilayers, thus suggesting that transmembrane diffusion cannot be responsible for its cellular internalisation. Novel dialysis experiments and isothermal titration calorimetry were found to be fast, reliable, and versatile tools for assessing membrane translocation also of other charged compounds, thereby eliminating the need for specific reporter groups.

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13125 BERLIN
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