Chemical Protein Synthesis by Hydroxylamine-Involved Ligation of Peptides.

Area of Science:

• Chemical Biology
• Synthetic Chemistry
• Biochemistry

Background:

• Chemical protein synthesis is crucial for biological studies.
• Existing ligation methods often require specific amino acid residues, limiting their applicability.
• A ligation strategy independent of specific amino acid sites is highly desirable.

Purpose of the Study:

• To develop an efficient and chemoselective peptide ligation method.
• To enable the synthesis of long peptides with native amide bonds without protecting groups.
• To demonstrate the utility of the method in synthesizing complex proteins like ubiquitin.

Main Methods:

• Utilizing chemoselective ligation between C-terminal peptide thioesters and N-terminal aminoacyl-N-hydroxy peptides in aqueous solution.
• Employing a sequential S,O-ester exchange and O,N-acyl transfer mechanism.
• Reducing N-hydroxyl peptides using zinc in an acidic aqueous medium to form native amide bonds.

Main Results:

• An efficient hydroxylamine-involved ligation (HAL) method was established.
• The ligation proceeds in water at room temperature, yielding O-acyl isopeptides and O,N-acyl transfer products.
• Reduction of intermediates afforded long peptides with native amide bonds.
• The HAL method was successfully applied to the synthesis of ubiquitin.

Conclusions:

• The hydroxylamine-involved ligation (HAL) provides an effective protocol for chemical protein synthesis.
• This method overcomes limitations of site-specific amino acid requirements in peptide ligation.
• The HAL strategy is a versatile tool for synthesizing complex peptides and proteins.