School of Chemistry and Biochemistry, National Centre of Competence in Research (NCCR) Chemical Biology, University of Geneva , Geneva 1211, Switzerland.
J Am Chem Soc. 2014 Apr 23;136(16):6069-74. doi: 10.1021/ja501581b. Epub 2014 Apr 15.
Substrate-initiated, self-inactivating, cell-penetrating poly(disulfide)s (siCPDs) are introduced as general transporters for the covalent delivery of unmodified substrates of free choice. With ring-opening disulfide-exchange polymerization, we show that guanidinium-rich siCPDs grow on fluorescent substrates within minutes under the mildest conditions. The most active siCPD transporters reach the cytosol of HeLa cells within 5 min and depolymerize in less than 1 min to release the native substrate. Depolymerized right after use, the best siCPDs are nontoxic under conditions where cell-penetrating peptides (CPPs) are cytotoxic. Intracellular localization (cytosol, nucleoli, endosomes) is independent of the substrate and can be varied on demand, through choice of polymer composition. Insensitivity to endocytosis inhibitors and classical structural variations (hydrophobicity, aromaticity, branching, boronic acids) suggest that the best siCPDs act differently. Supported by experimental evidence, a unique combination of the counterion-mediated translocation of CPPs with the underexplored, thiol-mediated covalent translocation is considered to account for this decisive difference.
底物引发的、自失活的、细胞穿透性聚（二硫键）（siCPD）被引入作为通用载体，用于共价传递未经修饰的、自由选择的底物。通过开环二硫键交换聚合，我们表明在最温和的条件下，富含胍的 siCPD 在几分钟内就在荧光底物上生长。最活跃的 siCPD 转运体在 5 分钟内进入 HeLa 细胞的细胞质，并在不到 1 分钟内解聚以释放天然底物。使用后立即解聚，在细胞穿透肽（CPP）具有细胞毒性的情况下，最佳 siCPD 在毒性条件下是非毒性的。细胞内定位（细胞质、核仁、内体）与底物无关，可通过选择聚合物组成按需改变。对胞吞抑制剂和经典结构变化（疏水性、芳香性、支化、硼酸）不敏感表明，最佳 siCPD 的作用方式不同。实验证据支持一种独特的组合，即 CPP 的反离子介导的易位与未充分探索的、硫醇介导的共价易位相结合，被认为是这种决定性差异的原因。
