Selection of anionic dopant for quantifying desialylation reactions with MALDI-FTMS

Area of Science:

• Analytical Chemistry
• Biochemistry
• Glycobiology

Background:

• Matrix-assisted laser desorption/ionization-mass spectrometry (MALDI-MS) is a powerful tool for analyzing biomolecules.
• Analyzing neutral oligosaccharides alongside acidic ones in a single mixture presents analytical challenges.
• Existing methods may not offer optimal sensitivity or ease of preparation for diverse oligosaccharide analyses.

Purpose of the Study:

• To investigate alkylsulfonates as novel anion dopants for MALDI-MS analysis of neutral oligosaccharides.
• To enable the simultaneous detection and quantification of neutral and acidic oligosaccharides in mixed samples.
• To evaluate the performance of alkylsulfonates compared to traditional dopants like sulfate.

Main Methods:

• Utilized alkylsulfonates as anion dopants in the MALDI-MS process for neutral oligosaccharides.
• Formed quasimolecular ions by the interaction of oligosaccharides with deprotonated alkylsulfonates.
• Employed Fourier-transform mass spectrometry (FTMS) to analyze oligosaccharide mixtures.

Main Results:

• Alkylsulfonates effectively facilitated the MALDI-MS analysis of neutral oligosaccharides, from disaccharides to complex branched structures.
• The performance of alkylsulfonates was comparable to sulfate (HSO4-) in terms of signal-to-noise ratio, sensitivity, and ease of preparation in negative ion mode.
• Established a calibration curve using alkylsulfonates, demonstrating a linear relationship between MALDI-FTMS signals and molar ratios of neutral and sialylated oligosaccharides.
• Successfully monitored the product of a desialylation reaction, showcasing the method's utility in reaction monitoring.

Conclusions:

• Alkylsulfonates serve as effective anion dopants for the MALDI-MS analysis of neutral oligosaccharides.
• This approach significantly expands the capability of MALDI-MS to analyze complex mixtures containing both neutral and acidic oligosaccharides.
• The developed method offers a sensitive, reliable, and versatile tool for oligosaccharide quantification and reaction monitoring in chemical and biological studies.