Study on generation of glycoprotein by recombinant technology.

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It is known that the oligosaccharides of glycoproteins contributes to the physiological characteristics of the protein, including hydrophilicity, electric charge, resistance to ptotease, and pH and temperature stability. This study was designed to establish the production system of glycoproteins bearing biological activity by using the techniques including gene technology, biochemistry and organic synthesis. We have synthesized biologically important peptide fragment carrying silly Lex antigen by employing chemoenzymatic solid-phase synthesis. In addition, we synthesized O-glycosilated fragments (sialoglycoprotein, glycophorin A), N-linked core pentasaccharide, and glycopeptides corresponding to carbohydrate-protein linkage region of cell-surface proteoglycans. We have succeeded to produce highly glycosilated recombinant Equine chorionic gonadotropin (eCG), rat placental lactogen, and rat leukemia inhibitory factor (LIF) by using mammalian cells. Interestingly, eCG consists of highly glycosilated a- and b-subunits, and its elicits response characteristic of both follicle stimulating hormone (FSH) and luteinizing hormone (LH). We found that the dual activity of eCG,LH-like and FSH-like activities, could be separated by removal of the N-linked oligosaccharides on the a-subunit Asn 56 or carboxy-terminal peptide associated O-linked oligosaccharides. In addition, we have established Baculovirus/insect cell system to produce glycosilated proteins including envelop glycoproteins of human hepatitis C virus and human FSH.