BUILDING UNITS OF OLIGOSACCHARIDES .109. SYNTHESIS OF MODIFIED OLIGOSACCHARIDES OF N-GLYCOPROTEINS FOR SUBSTRATE-SPECIFICITY STUDIES OF N-ACETYLGLUCOSAMINYLTRANSFERASE-I

A series of modified derivatives of the trisaccharide octyl alpha-D-Ma n(1-->3)-[alpha-D-Man(1-->6)]-beta-D-Man were synthesized for substrat e specificity studies of N-acetylglucosaminyltransferase I(GlcNAc-T I) . The hydroxyl groups at C-3, C-4 and C-6 of the alpha(1-->3)-linked M annose were replaced by hydrogen and methoxy groups. At the alpha(1--> 6)-linked mannose the hydroxyl group at C-2 was deoxygenated and the h ydroxyl groups at C-3, C-4 and C-6 were replaced by methoxy groups. Th e syntheses of the ten trisaccharides were carried out by the intercha ngeable combination of modified building blocks. The trichloroacetimid ate method was favourable for all glycosylation steps.