Oligosaccharides from M-active sialoglycopeptides of human erythrocytes

Abstract

A sialoglycopeptide released from human type M erythrocytes by incubation with trypsin was treated with 0.1 M NaOH containing 0.4 M NaBH 4. Nine low molecular weight sugars and oligosaccharides were released, including four which had N-acetylgalactosaminitol at the “non-reducing” terminus. All of these appear to be derived or derivable from a tetrasaccharide containing two sialic acids, one galactose and one galactosamine with the latter linked O-glycosidically to serine or threonine. Sialoglycopeptides with M or N bood group activity are liberated from the surface of human erythrocytes on incubation with trypsin ( Mäkela et al , 1960 ; Cook et al , 1960 ; Eylar et al , 1962 . A previous report ( Winzler et al , 1967 ) has established that such glycopeptides have a portion of their carbohydrate linked to the peptide chain by alkali-labile, O-glycosidic bonds. In the present paper the nature of the oligosaccharides released by treating sialoglycopeptides with alkaline borohydride will be considered.