Asparaginylglucose: Novel Type of Carbohydrate Linkage

The Halobacterial cell wall glycoprotein was recently shown to contain two types of sulfated saccharides: a repetitive saccharide and a nonrepetitive saccharide composed of glucuronic acid and glucose. A new type of N-glycosidic linkage is found in this latter type of saccharide: glucose is N-glycosidically linked to the polypeptide chain through the amido nitrogen of an asparagine residue, as shown by chemical analyses, proton magnetic resonance spectroscopy, and mass spectroscopy of an isolated asparaginyl saccharide. The only N-glycosidic linkage known so far is between the amido nitrogen of asparagine and N-acetylglucosamine.