A Ligase-Based Two-Step Approach for the Generation of Bicyclic Peptides Containing a Benzylphenyl Thioether...

Area of Science:

• Biochemistry
• Peptide Chemistry
• Molecular Biology

Background:

• Conventional bicyclic peptide synthesis can be complex and may impact phage display libraries.
• Developing efficient and biocompatible methods for peptide cyclization is crucial for drug discovery.

Purpose of the Study:

• To establish a ligase-mediated two-step strategy for synthesizing bicyclic peptides containing a benzyl phenyl thioether arm.
• To enable bicyclization under mild conditions compatible with phage display.

Main Methods:

• Utilized peptide ligases (SrtA or OaAEP1) to introduce arylthiol groups into parent peptides.
• Performed peptide bicyclization using tetramethylbenzidine (TBMB) under low concentration or pH conditions.
• Assessed the impact of TBMB on phage infectivity to ensure library diversity preservation.

Main Results:

• Successfully prepared unique bicyclic peptide molecules with a benzyl phenyl thioether arm.
• Demonstrated that the ligase-mediated bicyclization can occur under mild conditions due to the lower pKa of aryl thiols.
• Confirmed that low TBMB concentrations minimally affect phage infectivity, preserving library diversity.

Conclusions:

• Established a biocompatible, ligase-mediated two-step strategy for bicyclic peptide synthesis.
• The method is suitable for preparing diverse libraries of cyclic peptides for drug discovery.
• This approach holds potential for discovering novel bioactive cyclic peptide ligands.