| Research Abstract |
We established some synthetic routes of di-, tri, and tetrasaccharides, which are involved in glycoconjugate, through glycosidase-mediated transglycosylation and glycosyltransferase. These synthetic oligosaccharides were used for preparing glycopolymer as probes in carbohydrate-protein interaction studies.
1. Mucin-type oligsaccharide
Galbeta1-3 (GlcNAcbeta1-6) GalNAcalpha-OC_6H_4NO_2-p (1), whichis a carbohydrate region of mucin type 2 core, was enzymatically by the consecutive elongation of Gal and GlcNAcresidues to GalNAcalpha-OC_6H_4NO_2-p in two stages. Galbeta1-3GalNAcalpha-OC_6H_4NO_2-p (2) was firstly prepared by using galactosyl ation from lactose to GalNAcalpha-OC_6H_4NO_2-p. The resulting 2 was transformed into the desired compound 1 through Nocardia orientalis beta-N-acetylhexiosaminidase-mediated transglycosylation.
2. N-Acetylglucosdaminyl trisaccharide
3'-O-beta-N-acetylglucosaminyl-N-acetyllactosamine glycoside (3, GlcNAcbeta1-3Galbeta1-4GlcNAcbeta-OC_6H_4NO_2-p), which is the common trisaccharide unit of poly-N-acetyllactosamine, was synthesized through N-acetylglucosaminyl transfer by beta-N-acetylhexosaminidase from N.orientalis. In this case, when an inclusion complex of p-nitrophenyl beta-N-acetyllactosamine acceptor with alpha-cyclodextrin was used, the regioselectivity of glycosidase-mediated formation of the desired trisaccharide glycoside (3) was substantially changed.
3. Glycopolymer
N-Acetyllactosamine and its related compounds were used to transform into artificial glycopolymer. Two types of glycopolymers, whose main chain are polyacryl chain and polyglutamic scid peptide chain, were synthesized and used as modelin oligosaccharide-lection analysis. These water-soluble glycopolymers were shwon to interact specifically with the corresponding lectin, no matter how many side chains of the polymers are short-chain length such as disaccharide unit.
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