Characterization of the O-glycosidically linked oligosaccharides of rat erythrocyte membrane sialoglycoproteins

Abstract

The carbohydrate units of the rat erythrocyte membrane sialoglycoprotein rSGP-4 [Edge, A. S. B., & Weber, P. (1981) Arch. Biochem. Biophys. 209, 697-705] have been characterized. All of the carbohydrate of this Mr 19,000 glycoprotein occurs in O-glycosidic linkage to the peptide; following alkaline borohydride treatment and chromatography on Bio-Gel P-2, sialic acid containing oligosaccharides terminating in N-acetylgalactosaminitol were obtained. Their structures were determined by compositional analysis, exoglycosidase digestions, alkaline sulfite degradation, and periodate oxidation. The oligosaccharides were characterized for molecular weight and linkage by direct chemical ionization and gas-liquid chromatography/mass spectrometry, respectively. The structures are proposed to be NeuAc alpha 2----3Gal beta 1----3GalNAc-ol, Gal beta 1----3(NeuAc alpha 2----6)GalNAc-ol, NeuAc alpha 2----3Gal beta 1----3(NeuAc alpha 2----6)GalNAc-ol, and NeuAc alpha 2----3Gal beta 1----3(NeuAc alpha 2----3Gal beta 1----4GlcNAc beta 1----6)GalNAc-ol. Two of the N-acetylglucosamine-containing hexasaccharides were present per molecule of rSGP-4 along with two trisaccharides and seven tetrasaccharides.

Expression of mucin-associated tumor antigens is altered by cell density

“…Oligosaccharides were chromatographed on a 2-ml column of AG50W-X8 (100-200 mesh, H 1 ; Bio-Rad, Hercules, CA). The sample was eluted with 15 ml distilled water, 15 ml 50% ethanol and 10 ml 1 M NH 4 OH (to elute peptidic material; Edge et al, 1986). Radioactivity eluted with water (the oligosaccharide fraction) was lyophilized and resuspended in 2 mM Tris base prior to application to a 1-ml column of QAE-Sephadex (Varki and Kornfeld, 1980).…”

The size of the C-chain maltosaccharide of glycogen: evidence for the presence of only a single branch

“…In contrast to acid, heating in alkaline solution has no effect on α-1,4-glucosidic linkages (Somogyi, 1957). Borohydride was included to avoid alkaline degradation of the released maltosaccharides (Edge et al, 1986). No cleavage of glucosidic bonds occurred when standard maltosaccharides were subjected to the alkaline-borohydride treatment under the conditions used (Figure 1).…”