|Budget Amount *help
¥2,000,000 (Direct Cost : ¥2,000,000)
Fiscal Year 1995 : ¥600,000 (Direct Cost : ¥600,000)
Fiscal Year 1994 : ¥1,400,000 (Direct Cost : ¥1,400,000)
There is high currentinterest in developing synthetic routes to oligosaccharides involved in glycoconjugates. We established three synthetic routes of di- and trisaccharides, which are involved in glycoconjugate, through glycosidase-mediated transglycosylation. These synthetic oligosaccharides would be used for preparing glycopolymer as probes in carbohydrate-protein interaction studies.
Firstly, Manbeta1-4GlcNAcbeta1-4GlcNAc, which is the common structural feature at the core region of most of the N-glycoproteins, was regioselectively synthesized from mannotriose and N,N'-diacetylchitobiose utilizing beta-D-mannanase from Aspergillus niger. Secondary, Galbeta1-3GalNAcalpha-OC_6H_4NO_2-p, which is a mimic unit at carbohydrate region of mucin type, was regioselectively synthesized from lactose and p-nitorpheny1 N-acetyl-a-galactosaminide uitilizing porcine testes beta-D-galactosidase-mediated transglycosylation^<1)>. Finally, Lacto-N-triose II glycoside, which is the common trisacccharide unit of glycosphingolipids, with two beta-(1-6)-linked isomers were synthesized through N-acetylglucosaminyl transfer by beta-N-acetylhexosaminidase from Nocardia orientalis. In this case, when an inclusion complex of p-nitrophenyl lactoside acceptor with beta-cyclodextrin was used, the regioselectivity of glycosidase-catalyzed formation of trisaccharide glycoside was substantially changed. It resulted not only in a significant increase of an overall yield of transfer products, but also in the proportion of the desired compound (GlcNAcbeta1-3Galbeta1-4Glcbeta-OC_6H_4NO_2-p). Furthermore, glycopolymers containing a series of beta-galactosyl-disaccharides were synthesized^<3)> and used as model in oligosaccharide-lectin interaction analysis. Their interaction with various lectins was investigated by double diffusion test and the inhibition of hemagglutinating activity of lectins. These water-soluble glycopolymers were shown to be an useful tool as probes of carbohy drate recognition.