Glycosaminoglycans (GAGs) or mucopolysaccharides are a class of highly negatively charged polysaccharides, which are present in all mammalian cells and involved in various important biological events such as growth factor signaling, blood coagulation, brain development and neural stem cell migration. GAGs, except for hyaluronic acid, are commonly found covalently linked to proteoglycans (PGs). These PGs typically start with a common tetrasaccharide linkage region (GlcAβ1-3Galβ1-3Galβ1-4Xyl) that links to a serine residue on the core protein. The tetrasaccharide linkage region is then elongated to polysaccharides composed of disaccharide repeating units of chondroitin sulfate (CS) or heparan sulfate (HS). In this dissertation, we first discussthe recent advancesin the understanding of biosynthetic enzymes involved in the synthesis of the tetrasaccharide linkage region in chapter 1 and focus on the expression and the relationship between these enzymes. Building on the knowledge of these enzymes, in chapter 2, we report a new method using commercially available EAH Sepharose as the solid support to synthesize tetrasaccharide linkage region bearing glycopeptides. This method eliminates the tedious traditional glycosyl amino acid synthesis, greatly reducing the time need for tetrasaccharide linkage region construction. We further modified the synthesized linkage region with CS transferase and sulfotransferase to complete the synthesis of multiple CS-bearing glycopeptides. Notably, the dodecasaccahride bearing glycopeptide is the largest GAG-bearing glycopeptide synthesized to date. CSPG plays important roles in biological events, to better understand the mechanism, it is important to map the expression level and the types of CSPG. In chapter 3, an enzymatic method was developed to label and enrich CSPG in biospecimen and various fragmentation methods have been explored for quantitative CSPG mapping.
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