BUILDING UNITS OF OLIGOSACCHARIDES .107. SYNTHESIS OF MODIFIED OLIGOSACCHARIDES OF N-GLYCOPROTEINS FOR SUBSTRATE-SPECIFICITY STUDIES OF N-ACETYLGLUCOSAMINYLTRANSFERASE-II

Several modified derivatives of the tetrasaccharide Man-(1-->3)-[alpha -D-Man-(1-->6)]-beta-D-Man-Octyl (1) were synthesized for substrate sp ecifity studies of N-acetylglucosaminyltransferase II (GlcNAcT II). Th e hydroxyl groups at C-3, C-4 or C-6 of the alpha(1-->6)-linked Man re sidue and the hydroxyl groups at C-3 and C-6 of the alpha(1-->3)-linke d Man were replaced by deoxy groups. All five tetrasaccharides were sy nthesized by a block synthesis by using deoxy saccharide residues. The trichloroacetimidate method was particulary successful for synthesizi ng the glycosidic linkages. The modified compounds have been tested as substrates for N-acetylglucosaminyltransferase II (GlcNAcT II) from r at liver. The substate specificity of GlcNAcT II will be discussed.