Polypeptide Preparation by β-Lactone-Mediated Chemical Ligation

Area of Science:

• Synthetic chemistry
• Biochemistry
• Peptide synthesis

Background:

• Native chemical ligation (NCL) is a key method for synthesizing peptides and proteins.
• Traditional NCL struggles with sterically hindered residues and can cause epimerization.
• C-terminal thioesters of β-branched amino acids are particularly prone to slow reactions, epimerization, and hydrolysis.

Purpose of the Study:

• To develop an epimerization-free NCL method for sterically congested peptide synthesis.
• To overcome the limitations of traditional NCL with challenging amino acid residues.

Main Methods:

• A novel β-lactone-mediated native chemical ligation strategy was employed.
• This method facilitates chemoselective coupling of C-terminal thioester peptides with N-terminal thiol peptides.
• The approach was validated for constructing sterically hindered Thr residues and preparing cyclic peptides.

Main Results:

• The β-lactone-mediated NCL proceeds rapidly and without detectable epimerization.
• The method demonstrates broad side-chain tolerance.
• Successfully applied to synthesize challenging cyclic peptides and polypeptidyl thioesters.

Conclusions:

• β-lactone-mediated NCL offers an efficient and epimerization-free solution for synthesizing sterically hindered peptides.
• This technique expands the scope of NCL for creating complex peptide structures.
• Provides a valuable tool for peptide and protein research and development.