Membrane potential plays various key roles in live bacterial and eukaryotic cells. So far, the effects of membrane potential on action of antimicrobial peptides (AMPs) and cell-penetrating peptides (CPPs) have been examined using cells and small lipid vesicles. However, due to the technical drawbacks of these experiments, the effect of membrane potential on the actions of AMPs and CPPs and the elementary processes of interactions of these peptides with cell membranes and vesicle membranes are not well understood. In this short review, we summarize the results of the effect of membrane potential on the action of an AMP, lactoferricin B (LfcinB), and a CPP, transportan 10 (TP10), in vesicle membranes revealed by the single giant unilamellar vesicle (GUV) method. Parts of the actions and their elementary steps of AMPs and CPPs interacting vesicle membranes under membrane potential are clearly revealed using the single GUV method. The experimental methods and their analysis described here can be used to elucidate the effects of membrane potential on various activities of peptides such as AMPs, CPPs, and proteins. Moreover, GUVs with membrane potential are more suitable as a model of cells or artificial cells, as well as GUVs containing small vesicles.
Keywords: Antimicrobial peptides; Artificial cells; Bio-imaging; Cell-penetrating peptides; Membrane potential; Single giant unilamellar vesicles.