Automated Synthesis of Algal Fucoidan Oligosaccharides

Area of Science:

• Marine biology
• Carbohydrate chemistry
• Biochemistry

Background:

• Fucoidan, a sulfated polysaccharide from algae, is crucial for marine carbon sequestration and has diverse bioactivities.
• The structural complexity of fucoidan limits detailed structure-function relationship studies.
• Well-defined fucoidan oligosaccharides are needed for precise molecular investigations.

Purpose of the Study:

• To develop an automated method for synthesizing well-defined fucoidan oligosaccharides.
• To utilize these synthesized oligosaccharides for characterizing fucoidan-acting enzymes and antibodies.
• To investigate the structural basis of fucoidan bioactivity and its role in marine ecosystems.

Main Methods:

• Automated synthesis of linear and branched α-fucan oligosaccharides with defined linkages and sulfation patterns.
• Characterization of fucoidan glycoside hydrolases (GH107) using synthesized oligosaccharides.
• Development of a fucoidan microarray for antibody specificity screening.
• Nuclear Magnetic Resonance (NMR) studies using synthesized oligosaccharides as standards.

Main Results:

• Successfully synthesized complex fucoidan oligosaccharides with up to 20 glycosidic linkages and 11 sulfate monoesters.
• Characterized two endo-acting GH107 enzymes and confirmed algal fucoidan structures using synthesized standards.
• Developed a fucoidan microarray that revealed specificities of monoclonal antibodies (mAbs), including cross-reactivity of mAb BAM4 and epitope specificity of mAb BAM2.
• Identified fucoidan with structural homology to brown algae fucoidan in the marine diatom Thalassiosira weissflogii.

Conclusions:

• Automated glycan assembly provides crucial access to well-defined fucoidan oligosaccharides.
• These synthesized oligosaccharides are essential tools for advancing molecular-level understanding of fucoidan's roles in medicine and carbon sequestration.
• The study provides a foundation for future research into fucoidan structure-function relationships and applications.