EVIDENCE FOR THE COVALENT LINKAGE OF CARBOHYDRATE POLYMERS TO A GLYCOPROTEIN FROM STREPTOCOCCUS-SANGUIS

The platelet aggregation-associated protein (PAAP) from Streptococcus sanguis contains 39% carbohydrate in rhamnose-rich polysaccharides. Sy nthesized by cultured protoplasts, these polysaccharides were shown to be covalently linked to this cell wall protein using specific inhibit ors of glycosylation, glycosidase treatment, amino acid and carbohydra te analyses of prepared minimal glycopeptides and isolated protein, an d NMR spectroscopy. To our knowledge, this is the first direct proof o f an N-asparaginyl linkage of carbohydrate to a eubacterial protein.