A toolbox of diverse linkers for navigating the cellular efficacy landscape of stapled peptides.

Stapled peptides have great potential as modulators of protein-protein interactions (PPIs). However, there is a vast landscape of chemical features that can be varied for any given peptide, and identifying a set of features that maximizes cellular uptake and subsequent target engagement remains a key challenge. Herein we present a systematic analysis of staple functionality on the peptide bioactivity landscape in cellular assays. Applying a 'toolbox' of diversified dialkynyl linkers to the stapling of MDM2-binding peptides via a double-click approach, we conduct a study of cellular uptake and p53 activation as a function of the linker. Minor changes in the linker motif and the specific pairing of linker with peptide sequence can lead to substantial differences in bioactivity, a finding which may have important design implications for peptide-based inhibitors of other PPIs. Given the complexity of the structure-activity relationships involved, the toolbox approach represents a generalizable strategy for optimization when progressing from in vitro binding assays to cellular efficacy studies.