Studies on Glycobilogy

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1) Studies on new technologies for glycan analysis :Specificity studies on plant lectins demonstrated that the binding specificity of a lectin is so strict that use of various lectin columns with distinct specificity in combination allow us to isolate a glycan chain from a mixture of glycans and elucidate its partial structure. A new technology in ^1H-NMR analysis (relayed HOHAHA) was introduced very effectively for the structural analysis of acidic oligosaccharides isolated from human milk. Two new types of enzymatic activities which cleave bonds in the carbohydrate-protein linkage regions were found : one (endo-alpha-NU-acetylgalactosaminidase) acted on mucin-type glycoproteins with a broad specificity and the other (endo-beta-galactosidase) acted on proteoglycans. These enzymes were partially purified.2) Studies on biological functions of glycans :Glycans from a cell adhesion molecule on lymphocytes were found to have tri-and tetra-anntenary complex-type glycans modified with the attachment of N-acetyllactosamine, Lewis X and sialyl Lewis X structure. The presence of a receptor specific for chondroitin 4-sulphate on fibroblasts was established. A gene encoding a macrophage lectin. asialoglycoprotein binding protein (ASGP-BP) was cloned and its base sequence was determined. The elucidated amino acid sequence of the macrophage lectin was very similar to that of the hepatic ASGP-BP but was clearly distinct from the latter. Sugar binding sites of plant lectins were elucidated by utilizing gene recombinant technology. Monoclonal antibodies recognizing cancer associated mucin-type oligosaccharides were prepared.