Chemical Ligation of Backbone N-hydroxylated Peptides

Area of Science:

• Chemical Biology
• Organic Chemistry
• Biochemistry

Background:

• Hydroxamate groups facilitate amide bond formation via intramolecular O-acyl capture and O→N acyl transfer.
• Peptide synthesis often requires protecting groups for reactive side chains and termini.

Purpose of the Study:

• To develop a general and efficient peptide ligation strategy using backbone N-hydroxy peptide (NHP) fragments.
• To demonstrate the compatibility and versatility of NHP ligation for synthesizing complex peptides and proteins.

Main Methods:

• Utilizing the reactivity of backbone NHP fragments for coupling with peptide thioesters in aqueous buffer.
• Employing NHP ligation followed by N─O bond reduction to restore native peptide bonds.
• Synthesizing miniproteins and the natural product talarolide A to showcase the method's applicability.

Main Results:

• NHP ligation demonstrated efficient coupling of unprotected peptide fragments in aqueous buffer.
• The method showed broad compatibility with various N-terminal residues, including β-branched, aromatic, charged, and N-methylated amino acids.
• Successful synthesis of miniproteins with modulated folding and thermal stability, and the macrocyclic NHP natural product talarolide A was achieved.

Conclusions:

• Backbone NHP ligation is a robust and broadly applicable strategy for peptide and protein synthesis.
• This method simplifies peptide coupling by avoiding protecting groups and operating in aqueous conditions.
• NHP ligation expands the synthetic toolbox for creating complex peptidomimetics and biologically active peptides.