COMBINED CHEMICAL ENZYMATIC-SYNTHESIS OF A DIDEOXYPENTASACCHARIDE FOR USE IN A STUDY OF THE SPECIFICITY OF N-ACETYL-GLUCOSAMINYLTRANSFERASE-III

The biantennary oligosaccharide glycoside beta-D-GlcpNAc-(1 --> 2)-alpha-D-Manp-(1 --> 3)-[beta-D-GlcpNAc-(1 --> 2)-alpha-D-Manp-(1 --> 6)]-beta-D-Manp-OR is a potential substrate for N-acetylglucosaminyltransferases (GlcNAcTs) III-V. The dideoxypentasaccharide glycoside beta-D-GlcpNAc-(1 --> 2)-4-deoxy-alpha-D-lyxo-Hexp-(1 --> 3)-[beta-DGlcpNAc-(1 --> 2)-6-deoxy-alpha-D-Manp-(1 --> 6)]-beta-D-Manp-O(CH2)7CH3 (5), where the hydroxyl groups that would be acted on by GlcNAcTs IV and V have been removed, was prepared as a possible specific acceptor for GlcNAcT-III. The strategy involved the chemical synthesis of beta-D-GlcpNAc-(1 --> 2)-4-deoxy-alpha-D-lyxo-Hexp-(1 --> 3)-[6-deoxy-alpha-D-Manp-(1 --> 6)]-beta-D-Manp-O(CH2)7CH3 and then addition of the last GlcpNAc residue using partially purified GlcNAcT-II from rabbit liver. Preliminary results, using detergent extracts from rat kidney, indicate that 5 is an acceptor for a GlcNAcT whose identity remains to be extablished.