title: Structural studies on the carbohydrate units of armadillo submandibular glycoprotein.
abstract: The structure of carbohydrate units of the major glycoprotein fraction of armadillo submandibular gland was investigated. Alkaline borohydride reductive cleavage of the glycoprotein resulted in the release of O-glycosidically linked mono- and disaccharide units. The monosaccharide was identified as N-acetylgalactosaminitol, whereas disaccharide contained of N-acetylneuraminic acid and N-acetylgalactosaminitol. Treatment of the native and desialyzed glycoprotein with alpha-N-acetylgalactosaminidase resulted in the removal of 60% and 96% of N-acetylgalactosamine, respectively. No cleavage of this sugar was affected by the action of beta-N-acetylhexosaminidase. Both N-acetylgalactosamine and N-acetylneuraminic acid were susceptible to oxidation with periodate. Analyses of the partially methylated N-acetylgalactosamine derivatives, obtained from the permethylated native glycoprotein, showed the presence of 3,4,6-tri-O-methyl-N-methylacetamidogalactose and 3,4-di-O-methyl-N-methylacetamidogalactose in a ratio of 1 : 0.4. Only 3,4,6-tri-O-methyl-N-methylacetamidogalactose was found in the hydrolysates of permethylated desialyzed glycoprotein. These results together with our previous data on chemical composition of the glycoprotein suggest that about 30% of the oligosaccharide chains consist of NeuAc alpha 2 leads to 6GalNAc alpha 1 leads to O-Thr(Ser) and 70% of GalNAc alpha leads to O-Thr(Ser).
mesh_terms: D000818:Animals; D001135:Armadillos / Q000378:metabolism*; D001894:Borohydrides; D002241:Carbohydrates / Q000032:analysis*; D055598:Chemical Phenomena; D002621:Chemistry; D006023:Glycoproteins; D006026:Glycoside Hydrolases; D008745:Methylation; D010084:Oxidation-Reduction; D012471:Salivary Proteins and Peptides; D013363:Submandibular Gland / Q000032:analysis*; D004490:Xenarthra / Q000378:metabolism*
chemical_list: D001894:Borohydrides; D002241:Carbohydrates; D006023:Glycoproteins; D012471:Salivary Proteins and Peptides; D006026:Glycoside Hydrolases