The structures α-D-GalNAc-( 1→3)-α-D-GalNAc-( 1→O)-L-Thr and α-D-GalNAc-( 1→6)-α-D-GalNAc-( 1→O)-L-Thr are present as cores 5 and 7 of the mucin-type glycoproteins. The preparation of the corresponding building blocks 10 and 15 is described. Compounds 10 and 15 can be used directly in a multiple-column solid-phase glycopeptide peptide synthesis. In the resulting peptides the azido groups are reduced and acetylated on the solid support. The products are cleaved from the resin and the carbohydrate part is deprotected. A series of 20 O-glycopeptides has been prepared.
A solid-phase oligosaccharide synthesis has been developed which utilises glycopeptides bound to the solid phase. The products are glycopeptides elongated at the saccharide chain. The glycosyl acceptors, which are assembled by simple solid-phase glycopeptide synthesis, contain 2-azido-2-deoxy-α-D-galactose with unsubstituted 3-OH or 6-OH groups, which can be glycosylated. Suitable glycosyl donors are perbenzoylated trichloroacetimidates of D-galactose or 2-amino-2-deoxy-D-glucose, although the 2-amino group must be protected with Teoc. A corresponding additional saccharide unit is added with a β-glycosidic linkage. With disaccharide donors, glycopeptides with linear trisaccharide side chains are obtained. By performing the solid-phase glycosylation synthesis twice in succession glycopeptides with branched trisaccharide chains have been obtained.
J. Biochem.(1977) 79.11-21.It is assumed that Gal.Glc.GalNAc.GlcNAc.and NeuAc , are of the D-configuration, Fuc of the L-configuration, and all sugars present in the pyranose form.' SphNAc indicates "ceramide part" composed of N-acetylsphingenine. " K.-A.Karlsson, unpuhlished data.'The formulae summarize various combinations (brackets combined with no brackets) of blood group ABH and Lewis determinants based on type 2 (No. 24) and type 1 (No.29) chains.All theoretical combinations have been found (and tested) except those with terminal Gal or GalNAc but lacking Fuc bound to the penultimate Gal.n = 1-5.Prepared by neuraminidase treatment of the major ganglioside of human erythrocytes (No. 25, Ref. 55).
