Lactone-Driven Ester-to-Amide Derivatization for Sialic Acid Linkage-Specific Alkylamidation

Area of Science:

• Glycobiology
• Analytical Chemistry
• Mass Spectrometry

Background:

• Sialic acids, found at the ends of glycans, play crucial roles in biological processes.
• Distinguishing sialic acid linkages is vital for understanding their specific functions.
• Current methods for sialic acid linkage analysis can be complex.

Purpose of the Study:

• To develop a novel, simplified method for sialic acid linkage-specific derivatization.
• To enable easier discrimination of sialyl linkages using mass spectrometry.
• To investigate age-related changes in N-glycans within cardiac muscle tissue.

Main Methods:

• Development of the Lactone-driven Ester-to-Amide Derivatization for Sialic acid linkage-specific Alkylamidation (LEAD-SALSA) method.
• Utilizing an intramolecular lactone intermediate for α-2,3/8-sialyl linkage-specific amidation of esterified sialyloligosaccharides.
• Applying density functional theory calculations to assess lactone stability and reaction energies.

Main Results:

• LEAD-SALSA successfully achieved α-2,3/8-sialyl linkage-specific amidation.
• The method demonstrated the accumulation of altered N-glycans in mouse cardiac muscle during aging.
• Lactone stability was identified as a critical factor for efficient ester-to-amide conversion.
• The method distinguished branching structures of galactose linked to sialic acid.

Conclusions:

• LEAD-SALSA provides a direct and simplified approach for sialylglycan discrimination.
• This method facilitates the study of sialyl linkage types and their associated physiological events.
• The findings contribute to a better understanding of glycoconjugate roles in aging and disease.