Discovering Serum Stable Protein-Protein Interaction Inhibitors with N‑Terminus-Capped Bicyclic Phage Libraries

Area of Science:

• Biochemistry
• Molecular Biology
• Drug Discovery

Background:

• Protein-protein interactions (PPIs) are crucial in biological processes but challenging to target with small molecules.
• Peptides are effective for PPI inhibition due to their size and specificity.
• Multicyclic peptides offer improved rigidity and resistance to degradation.

Purpose of the Study:

• To develop and evaluate N-terminus-capped bicyclic peptide phage libraries for targeting PPIs.
• To assess the stability and potency of these bicyclic peptides compared to their linear or disulfide precursors.

Main Methods:

• Construction of N-terminus-capped bicyclic phage libraries using a novel bischlorooxime N-hydroxysuccinimide (BC-OSu) cross-linker.
• Screening of these libraries against Keap1 and SARS-CoV-2 Spike proteins.
• Comparative analysis of bicyclic peptide stability in human serum versus disulfide precursors.

Main Results:

• Identification of multiple potent bicyclic peptide ligands against both Keap1 and SARS-CoV-2 Spike proteins.
• Demonstration of superior potency of bicyclic ligands over their disulfide counterparts.
• Significant enhancement in serum stability for N-terminus-capped bicyclic peptides compared to rapid degradation of disulfide precursors.

Conclusions:

• N-terminus-capped bicyclic phage libraries represent a promising strategy for developing stable and potent PPI inhibitors.
• The BC-OSu cross-linker facilitates the construction of robust bicyclic peptide structures.
• These findings highlight the therapeutic potential of engineered bicyclic peptides for various diseases and viral infections.