Effect of Preorganized Charge-Display on the Cell-Penetrating Properties of Cationic Peptides

The effect of preorganized versus undefined charge display on the cellular uptake of cationic cell-penetrating peptides (CPPs) was investigated by comparing conformationally well-defined guanidinylated oligoprolines with flexible oligoarginines. Flow cytometry and confocal microscopy studies with different cancer cell lines (HeLa, MCF-7, and HT-29) showed that preorganization of cationic charges in lateral distances of approximate to 9 angstrom enhanced the cellular uptake of CPPs. Binding affinity measurements revealed tighter binding of analogues of cell-surface glycans to the guanidinylated octaproline with localized charges compared to flexible octaarginine, a finding that was further correlated to the cellular uptake by studies with CHO cells deficient in glycans on the outer plasma membrane.