Glycosaminoglycans (GAGs) are linear acidic polysaccharides, ubiquitous molecules involved in a wide range of biological processes. Despite their seemingly simple structure, with a repeating backbone of alternating hexuronic acid and hexosamine dimers, GAGs present a highly complex structure, mainly due to their heterogeneous sulfation patterns. The commonly used method for compositional analysis of all GAGs is “disaccharide analysis”. GAGs are enzymatically depolymerized into disaccharides, derivatized with a fluorescent label, and then analysed through liquid chromatography. However, the time-consuming liquid chromatography is the limiting factor in the high throughput analysis of GAG disaccharides. To overcome this limitation, the authors used trapped ion mobility mass spectrometry (TIM-MS) for the separation of isomeric GAG disaccharides, reducing the measurement time from hours to a few minutes. This significant reduction in measurement time could revolutionize the field of GAG analysis.
A full set of disaccharides comprises twelve structures, with eight possessing isomers. Most disaccharides cannot be differentiated by TIM-MS in underivatized form. Therefore, chemical modifications to reduce sample complexity and enhance differentiability were developed. Quantification is performed using stable isotope labelled standards, which are easily available due to the nature of the performed modifications.
