Synthesis of Oligosaccharides Having a 5-Thio Sugar Moiety

Synthesis of Oligosaccharides Having a 5-Thio Sugar Moiety 

Oligosaccharides containing 5-thiopyranosyl units are potentially resistant to hydrolysis by exo or endo glycosidases and constitute tools to investigate oligosaccharide-receptor interactions. 

UDP-A-acetyl-5-thio-D-galactosamine (UDP-5.SGalNAc) was active as a donor substrate of lactose synthase, the complex of galactosyltransferase (EC 2.4.1.38) and lactalbumin. By tliis method the disaccharide /9-5SGalNAc/9(1 4)GlcNAc was prepared. UDP-5.S GalNAc was synthesized from an A -acetyIgalactosaininc 

and 4-SeH groups of glucopyranoside acceptors 383-385, inthe presence of triethylsilyl triflate as catalyst. The notable a-selectivity is attributed to the greater stability of the a anomers. 5 -Thiomaltoside, 4,5 -ditluomaltosidc, and 

4-seleno-5 -thiomaltoside were shown to be competitive inhibitors of maltose binding by glucoamylase G2, with AT values of 1.34,2.04, and 0.80 mM respectively.  

---