Protein–protein interactions (PPIs) are often mediated by helical, strand and/or coil secondary structures at the interface regions. We previously showed that non-naturally occurring, stable helical trimers of bicyclic β-amino acids (Abh) with all-trans amide bonds can block the p53–MDM2/MDMX α-helix–helix interaction, which plays a role in regulating p53 function. Here, we conducted docking and molecular dynamics calculations to guide the structural optimization of our reported compounds, focusing on modifications of the C-terminal/N-terminal residues. We confirmed that the modified peptides directly bind to MDM2 by means of thermal shift assay, isothermal titration calorimetry, and enzyme-linked immunosorbent assay (ELISA) experiments. Biological activity assay in human osteosarcoma cell line SJSA-1, which has wild-type p53 and amplification of the Mdm2 gene, indicated that these peptides are membrane-permeable p53–MDM2/MDMX interaction antagonists that can rescue p53 function in the cells.

蛋白质-蛋白质相互作用 (PPI) 通常由界面区域的螺旋、链和/或卷曲二级结构介导。我们之前展示了双环 β-氨基酸 (Abh) 的非天然存在的、稳定的螺旋三聚体与全反式酰胺键可以阻断 p53-MDM2/MDMX α-螺旋-螺旋相互作用，在调节 p53 功能中发挥作用。在这里，我们进行了对接和分子动力学计算，以指导我们报告的化合物的结构优化，重点是 C 端/N 端残基的修饰。我们通过热位移测定、等温滴定量热法和酶联免疫吸附测定 (ELISA) 实验证实了修饰肽直接与 MDM2 结合。具有野生型 p53 和Mdm2基因扩增的人骨肉瘤细胞系 SJSA-1 的生物活性测定表明，这些肽是膜渗透性 p53-MDM2/MDMX 相互作用拮抗剂，可以挽救细胞中的 p53 功能。