3-Deoxy-3-Fluoro Mannuronic Acid Alginates: Stereoselective Automated Synthesis and Conformational Behaviour

Area of Science:

• Carbohydrate Chemistry
• Glycobiology
• Organic Synthesis

Background:

• Fluorination is a key strategy for modifying glycans, enabling the creation of tools for studying carbohydrate-protein interactions.
• Understanding the impact of modifications on glycan structure and function is crucial for developing novel biochemical tools.

Purpose of the Study:

• To investigate the effects of C-3 fluorination on mannuronic acid residues within β-1,4-d-mannuronic acid alginate fragments.
• To assess the impact of C-3 fluorination on the conformational preferences of the resulting oligosaccharides.

Main Methods:

• Synthesis of a 3-deoxy-3-fluoro d-mannuronate donor.
• Automated glycan assembly to create a library of C-3-F modified β-d-mannuronate oligosaccharides.
• Comprehensive Nuclear Magnetic Resonance (NMR) analysis to determine structural and conformational properties.

Main Results:

• The C-3 fluoride modification did not impede the β-stereoselectivity of the mannuronate system during synthesis.
• The 3-deoxy-3-fluoro units altered native inter-residue hydrogen bonds but did not significantly change the overall conformation of the alginate fragments.
• The overall conformation of the fluorinated oligosaccharides remained consistent with native β-1,4 mannuronic acid alginate.

Conclusions:

• C-3 fluorination of mannuronic acids is a well-tolerated modification in β-1,4-d-mannuronic acid alginate fragments.
• These fluorinated oligosaccharides serve as valuable structural tools for investigating glycan self-assembly and enzymatic processing.
• The study provides a foundation for further exploration of fluorinated glycans in biological systems.