Cell penetrating peptide (CPP) is a short, often cationic peptide that can translocate across cell membranes and effectively deliver various molecular cargos spanning from small molecules to macromolecules. With growing attention on CPP-based bioapplications, recent researches have explored the molecular requirement for efficient internalization and underscored that arginine and hydrophobic contents are crucial in increasing uptake efficiency of CPP. However, the relationship between the sequence and possible cytotoxicity of CPP is less known. Here we investigated how the arginine and tryptophan contents influence on cellular uptake efficiency and simultaneous cytotoxicity. In this modification, lysine and glycine in our newly discovered cell-permeable peptide were systematically substituted with arginine and tryptophan, respectively. Flow cytometry and confocal fluorescence images revealed that uptake efficiency increases for the peptides with higher arginine and tryptophan contents. The results were consistent with the previous researches showing that arginine forms bidentate hydrogen bonds with phosphate moieties of lipid to facilitate the peptide internalization whereas tryptophan contributes to the interaction with hydrophobic compartment of cell membrane. Interestingly, increase of arginine ratio induced higher cytotoxicity, possibly due to unstabilized cell surface. Optimized CPP sequence that has high uptake efficiency with low cytotoxicity was found when tryptophan was placed next to arginine. Our results indicate that modulization of arginine and tryptophan content of CPP can be used to design a biocompatible CPP-based delivery system.

Investigation on the relationship between cellular uptake efficiency and cytotoxicity of cell penetrating peptide by systematic sequence modulization

2019 Fall National Meeting

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