Structural Determination of Polysaccharides Lichenin Using Logically Derived Sequence Tandem Mass Spectrometry

Area of Science:

• Carbohydrate Chemistry
• Analytical Chemistry
• Biochemistry

Background:

• Polysaccharide structural determination traditionally involves complex, multi-step processes.
• Existing methods like gas chromatography-mass spectrometry and nuclear magnetic resonance require significant time, effort, and sample quantities.

Purpose of the Study:

• To introduce and demonstrate a novel mass spectrometry technique, logically derived sequence tandem mass spectrometry (LODES/MS), for efficient polysaccharide primary structure determination.
• To showcase the application of LODES/MS for elucidating the structure of the polysaccharide lichenin.

Main Methods:

• Polysaccharides are hydrolyzed into smaller units (monosaccharides, disaccharides, oligosaccharides).
• LODES/MS is employed to determine the structures of these resulting oligosaccharides.
• The method was specifically applied to determine the primary structure of lichenin.

Main Results:

• The repeating unit of lichenin was identified as An-Bn.
• Structure A: β-Glc-(1 → 4)-β-Glc-(1 → 4)-β-Glc-(1 → 3)-Glc.
• Structure B: β-Glc-(1 → 4)-β-Glc-(1 → 4)-β-Glc-(1 → 4)-β-Glc-(1 → 3)-Glc, with n ≥ 2 (n=1 not excluded).

Conclusions:

• LODES/MS significantly reduces the time, effort, and sample required for oligosaccharide structural analysis.
• This method offers a powerful and efficient tool for polysaccharide primary structure determination.
• LODES/MS provides a streamlined approach compared to conventional analytical techniques.