Structural Analysis of Intact Glycosaminoglycan Mixtures with Capillary Electrophoresis and High Resolution Tandem Mass Spectrometry

Glycosaminoglycans (GAGs), linear polysaccharides found near the cell membrane as proteoglycans and free oligosaccharides, play important roles regarding cell functions. GAGs have been implicated as potential biomarkers in many diseases like cancer and kidney related diseases and are used as therapeutics for many types of ailments. Because they are highly sulfated, complex GAGs have been analyzed with reverse polarity capillary electrophoresis (CE) and negative mode mass spectrometry. CE is a separation technique that separates analytes based on their size-to-charge ratio, with very low injection volume and fast elution time. 

For complex GAG mixtures EMASS-II nanoflow interface from CMP Scientifics has been used extensively. However, applying tandem mass spectrometry for structural analysis of complex GAG mixtures remains a challenge because of the labile sulfates. This presentation outlines experiments designed to improve the CE-MS/MS platform using the nanoflow interface with different background electrolytes and sheath liquids to increase the charge state of the GAGs in negative mode ionization to implement negative electron transfer dissociation, a fragmentation method that produces informative fragments and occurs quickly to be compatible with CE separation. Then, these methods are combined with the traditional CE-MS1 method for a comprehensive workflow for the structural analysis of complex GAG mixture.