A Tag-Free Platform for Synthesis and Screening of Cyclic Peptide Libraries

Area of Science:

• Chemical Biology
• Drug Discovery
• Peptide Chemistry

Background:

• Traditional macrocyclic peptide libraries require decoding tags for synthesis and screening.
• Identifying peptide binders in high-throughput screening (HTS) is often complex and resource-intensive.

Purpose of the Study:

• To develop a tag-free technology platform for synthesizing and screening cyclic peptide libraries.
• To identify novel peptide binders against biological targets, including therapeutic targets like HIV capsid protein.

Main Methods:

• Utilized intramolecular CyClick and DeClick chemistries (CCDC) for tag-free cyclic peptide library synthesis in solution.
• Employed a sensitivity-enhancing derivatization method with nano LC-MS/MS for low-concentration peptide sequencing.
• Validated identified peptide binders using microscale thermal shift assays (TSA), biolayer interferometry (BLI), and functional assays.

Main Results:

• Successfully synthesized diverse cyclic peptide libraries with various amino acids.
• Identified novel cyclic peptide binders against a monoclonal antibody.
• Discovered the first cyclic peptide binder for the HIV capsid protein, crucial for viral infections.

Conclusions:

• The tag-free CCDC platform offers an efficient method for cyclic peptide library synthesis and screening.
• This technology facilitates the discovery of potent peptide binders at picomolar concentrations.
• The identified binders represent significant advancements in therapeutic strategies against viral infections and other diseases.