Quantitative HILIC-Q-TOF-MS Analysis of Glycosaminoglycans and Non-reducing End Carbohydrate Biomarkers via Glycan Reductive Isotopic Labeling
Amrita Basu, Stephanie Archer‐Hartmann, Pradeep Chopra, Mehrnoush Taherzadeh Ghahfarrokhi, Xiaolin Dong, Neil Patel, Yiwen Zhang, Biswa Choudhury, Kosuke Funato, Dhananjay Yellajoshyula, Geert‐Jan Boons, Parastoo Azadi, Ryan J. Weiss
Abstract
Glycosaminoglycans (GAGs) are linear, heterogeneous polysaccharides expressed on all animal cells. Sulfated GAGs, including heparan sulfate (HS) and chondroitin/dermatan sulfate (CS/DS), are involved in numerous physiological and pathological processes; therefore, precise and robust analytical methods for their characterization are essential to correlate structure with function. In this study, we developed a method utilizing hydrophilic interaction liquid chromatography coupled with time-of-flight mass spectrometry (HILIC-Q-TOF-MS) and glycan reductive isotopic reducing end labeling (GRIL) for the quantitative compositional analysis of HS and CS/DS polysaccharides. Lyase-generated disaccharides and commercial standards were chemically tagged on the reducing end with aniline stable isotopes, thus enabling the absolute quantification of HS and CS/DS disaccharides in complex biological samples. In addition, we adapted this workflow, in conjunction with new synthetic carbohydrate standards, for the quantification of disease-specific non-reducing end (NRE) carbohydrate biomarkers that accumulate in patients with mucopolysaccharidoses (MPS), a subclass of lysosomal storage disorders. As a proof of concept, we applied this method to measure NRE biomarkers in patient-derived MPS IIIA and MPS IIID fibroblasts, as well as in cortex tissue from a murine model of MPS VII. Overall, this method demonstrates improved sensitivity compared to previous GRIL-LC/MS techniques and, importantly, avoids the use of ion-pairing reagents, which are undesirable in certain mass spectrometry instrumentation and contexts. By combining the benefits of HILIC separation with isotopic labeling, our approach offers a robust and accessible tool for the analysis of GAGs, paving the way for advancements in understanding GAG structure and function.