Stable isotopic labeling-based quantitative targeted glycomics (i-QTaG).

Area of Science:

• Biochemistry
• Analytical Chemistry
• Glycomics

Background:

• Aberrant glycosylation is linked to various diseases.
• Mass spectrometry (MS) with stable isotopic labeling offers quantitative insights.
• Accurate quantification of N-glycans is crucial for disease biomarker discovery.

Purpose of the Study:

• To develop and validate a stable isotopic labeling-based quantitative targeted glycomics (i-QTaG) technique.
• To enable comparative and quantitative analysis of total N-glycans using MALDI-TOF MS.
• To assess the potential of i-QTaG for diagnosing and monitoring disease-associated glycosylation alterations.

Main Methods:

• Developed i-QTaG technique involving chemical derivatization (sialic acid neutralization, stable isotopic labeling).
• Utilized matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) for analysis.
• Validated the method using a model glycoprotein (bovine fetuin) and human serum samples with varying N-glycan ratios.

Main Results:

• The i-QTaG method demonstrated excellent linearity (R(2) > 0.99) with glycoprotein amounts.
• Relative intensity ratios of labeled N-glycans closely matched theoretical molar ratios.
• Identified significant up-regulation of Lewis antigen (~82%) in prostate cancer patient sera compared to normal controls.

Conclusions:

• The i-QTaG technique provides reliable comparative quantitation of total N-glycans.
• MALDI-TOF MS-based i-QTaG shows promise for diagnosing and monitoring glycosylation changes in diseases.
• This method has potential applications in disease diagnostics and biotherapeutic monitoring.