The Release of Oligosaccharides from Glycoproteins

Abstract

The release of oligosaccharides from glycoproteins is performed for two main reasons; first to allow further studies on the core protein, and second to elucidate the structure of the oligosaccharide moeities present. For further studies of the protein to be carried out it is essential that the amino acid peptide bonds remain intact during the release process, whereas this is not essential for further studies on the released oligosaccharides. Here we describe strategies for the release of both N-linked and O-linked oligosaccharides, which allow further characterization of both protein and oligosaccharide. N-linked oligosaccharides can be readily released enzymatically, and rational use of glycosidases, e.g., peptide N glycanase F (PNGase F), endo-β-N-acetylglucosaminidase H (Endo H), neuraminidase and endo-α-N-acetylgalactosaminidase (O-glycosidase) will reveal useful information on the type of oligosaccharide present. O-linked chains are more difficult to release as sequential glycosidase digestions (e.g., neuraminidase and O-glycosidase) will remove some but not all types of O-linked chain. For the release of all O-linked chains for further analysis a chemical method is required, which also degrades the protein.