title: The isolation and structure of the core oligosaccharide sequences of IgM.
abstract: Methods are presented for separating the three IgM heavy chain sialoglycopeptides associated with asparagines 170, 332, and 395. The core glycopeptide units containing the disaccharide fucosyl-N-acetylglucosamine were obtained through the use of an endo-beta-N-acetylglucosamindase from Diplococcus pneumoniae, following exoglycosidase treatment of the sialoglycopeptides. In addition to the core glycopeptides, high yields of a tetrasaccharide, (Man)3GlcNAc, were obtained. The fucose in the core disaccharide is glycosidically linked to the 6-O position of the N-acetylglucosamine residue in Asn-GlcNAc. This core unit is resistant to glycosyl asparaginase, but becomes susceptible to hydrolysis on removal of the fucosyl residue by a purified hen oviduct alpha-L-fucosidase. The core sequence of the immunoglobulin M sialoglycopeptides appears to be similar to that of most other asparagine-linked oligosaccharides in consisting of a basic unit composed of beta-D-Man-(1 leads to 4)beta-D-GlcNAc(1 leads to 4)beta-D-GlcNAc(1 leads to 4), but with L fucose linked alpha-(1 leads to 6) to the proximal GlcNAc. The two nonreducing terminal ends of (Man)3GlcNAc are linked to beta-D-Man by alpha-(1 leads to 3) and alpha(1 leads to 6) bonds, respectively.
mesh_terms: D000596:Amino Acids / Q000032:analysis; D001216:Asparagine; D006020:Glycopeptides / Q000032:analysis / Q000302:isolation & purification; D006026:Glycoside Hydrolases; D007075:Immunoglobulin M / Q000032:analysis*; D009844:Oligosaccharides / Q000032:analysis*
chemical_list: D000596:Amino Acids; D006020:Glycopeptides; D007075:Immunoglobulin M; D009844:Oligosaccharides; D001216:Asparagine; D006026:Glycoside Hydrolases