Multilayer Annotation Strategy AnnoSePS: Disentangling the Intricate Structure of Selenium-Containing Polysaccharides...

Area of Science:

• Analytical Chemistry
• Biochemistry
• Structural Biology

Background:

• Identifying selenium in polysaccharides is challenging due to complex structures.
• Existing database methods struggle with novel selenium-binding sites and isomers.
• Precise structural and positional mapping of selenium is crucial for understanding its biological role.

Purpose of the Study:

• To develop a database-independent strategy for identifying seleno-substituents in polysaccharides.
• To enable unbiased profiling and fine structural dissection of selenium-containing polysaccharides.
• To accurately map selenium's position and linkage within polysaccharide structures.

Main Methods:

• A multilayer annotation strategy (AnnoSePS) was developed.
• Snoop-triggered multiple reaction monitoring (Snoop-MRM) identified monosaccharides.
• Agglomerative hierarchical clustering and probabilistic modeling analyzed mass spectrometry data.
• Synthesis-driven approaches annotated glycosidic linkages.

Main Results:

• AnnoSePS successfully identified seleno-rhamnose, with selenium substituting the C-1 hydroxyl group via a Se-H bond.
• Predominant monosaccharides were galactose (25.19%), galacturonic acid (19.45%), and glucose (11.72%).
• T-Galactose (16.67%) and T-Galacturonic acid (11.54%) were the main linkage residues.

Conclusions:

• AnnoSePS provides a comprehensive, database-independent method for analyzing selenium-containing polysaccharides.
• The strategy enables detailed structural elucidation, including selenium localization and linkage composition.
• This approach significantly advances the identification and characterization of complex selenium-modified biomolecules.