Endosomal entrapment is a common bottleneck in various macromolecular delivery approaches. Recently, the polycationic peptide dfTAT was identified as a reagent that induces the efficient leakage of late endosomes and, thereby, enhances the penetration of macromolecules into the cytosol of live human cells. To gain further insights into the features that lead to this activity, the role of peptide sequence was investigated. We establish that the leakage activity of dfTAT can be recapitulated by polyarginine analogs but not by polylysine counterparts. Efficiencies of peptide endocytic uptake increase linearly with the number of arginine residues present. In contrast, peptide cytosolic penetration displays a threshold behavior, indicating that a minimum number of arginines is required to induce endosomal escape. Increasing arginine content above this threshold further augments delivery efficiencies. Yet, it also leads to increasing the toxicity of the delivery agents. Together, these data reveal a relatively narrow arginine-content window for the design of optimally active endosomolytic agents.

中文翻译：

---

用富含精氨酸的肽释放内体包埋

内体截留是各种大分子递送方法中的常见瓶颈。近来，聚阳离子肽dfTAT被鉴定为可诱导晚期内体的有效泄漏，从而增强大分子向活人细胞的细胞质中的渗透的试剂。为了进一步了解导致这种活性的特征，研究了肽序列的作用。我们确定，聚精氨酸类似物可概括dfTAT的泄漏活性，而聚赖氨酸对应物则不能。肽内吞摄取的效率随着存在的精氨酸残基数量的增加而线性增加。相反，肽胞质渗透显示阈值行为，表明诱导内体逃逸需要最少数量的精氨酸。将精氨酸含量增加到该阈值以上可进一步提高递送效率。然而，这也导致递送剂的毒性增加。这些数据一起揭示了用于设计最佳活性内溶体药物的相对较窄的精氨酸含量窗口。