Solid-Phase Oligosaccharide Synthesis with Highly Complexed Peptidoglycan Fragments.

Area of Science:

• Chemical Synthesis
• Immunology
• Carbohydrate Chemistry

Background:

• Peptidoglycan (PGN) fragments are recognized by Nod1 and Nod2 receptors, initiating inflammatory responses.
• A stable supply of PGN fragments is crucial for understanding these immune defense mechanisms.
• Synthesizing and purifying long PGN fragments is challenging due to poor solubility.

Purpose of the Study:

• To develop an efficient chemical synthesis method for long peptidoglycan (PGN) fragments.
• To overcome solubility limitations in the synthesis of PGN fragments.
• To provide a stable supply of PGN fragments for biological studies.

Main Methods:

• Solid-phase oligosaccharide synthesis (SPOS) using JandaJel™ Wang resin (JJ-Wang).
• Construction of an octasaccharide glycan chain via repeated glycosylation of β-1,4-linked disaccharide units (MurNAc and GlcNAc).
• Glycosylation in a mixed solvent (C4F9OEt/CH2Cl2/THF) to enhance substrate concentration via fluorophobic effect.
• Deprotection, N- and O-acetylation, and peptide condensation.
• Cleavage from the resin using trifluoroacetic acid (TFA).

Main Results:

• Efficient synthesis of the PGN octasaccharide in 19% overall yield over 10 steps.
• Successful N- and O-acetylation due to the high swelling property of JJ-Wang resin.
• Obtained the desired octasaccharide with dipeptides in 2.3% overall yield over 15 steps.

Conclusions:

• Solid-phase oligosaccharide synthesis (SPOS) provides an effective route for producing long PGN fragments.
• The developed method overcomes solubility issues, enabling the synthesis of complex PGN structures.
• This advancement facilitates further research into PGN-mediated immune signaling pathways.