Cell penetrating peptides (CPPs) are able to
translocate across cellular membranes and transport various cargoes, but the
uptake mechanisms are yet not fully understood. Our goal is to determine the
membrane binding properties and conformational features of two different types
of CPPs, in order to correlate them with the uptake efficiency and
toxicological effects. On the one hand, we compare stapeled amphiphilic
α-helical CPPs with their linear analogues. Furthermore, we have designed amphiphilic α-helical CPPs with a “charge
zipper” motif that utilizes intramolecular ladders of salt bridges for
compensating the net charge. Circular dichroism (CD) is used to determine the
extent of helicity in different lipid vesicles, and Oriented CD reveals the
helix alignment in the membrane. A high-throughput screening in model membranes
is used to measure the uptake efficiency of the CPP and leakage of the lipid
vesicles simultaneously. These experiments allow us to detect any aggregation
tendency of the CPPs and at the same time provide insight in the correlation
between the uptake efficiency with peptide structure, lipid composition, and
membrane curvature.