Suprastapled Peptides: Hybridization Enhanced Peptide Ligation and Enforced α-helical Conformation for Affinity Selection of Combinatorial Libraries

Stapled peptides with an enforced α-helical conformation have been shown to overcome major limitations in the development of short peptides targeting protein-protein interactions (PPI).  While the growing arsenal of methodologies to staple peptides facilitates their preparation, stapling methodologies are not broadly embraced in synthetic library screening.  Herein, we report a strategy leveraged on hybridization of short PNA-peptide conjugates wherein nucleobase driven assembly facilitates ligation of peptide fragments and constrains the peptide’s conformation into an α-helix.  Using native chemical ligation, we show that a mixture of peptide fragments can be combinatorially ligated and used directly in affinity selection against a target of interest.  This approach was exemplified with a focused library targeting the p-53 / MDM2 interaction. One hundred peptides were obtained in a one-pot ligation reaction, selected by affinity against MDM2 immobilized on beads and the best binders were identified by mass spectrometry.