Department of Chemistry Graduate School of Science, Osaka University

Organic Chemistry Division

Laboratory for Organic Biochemistry

Members

  • Yasuhiro KAJIHARA (Professor)
  • Ryo OKAMOTO (Associate Professor)
  • Yuta MAKI (Assistant Professor)

Contact

  • e-mail:
  • web page: http://www.chem.sci.osaka-u.ac.jp/lab/kajihara/index.html

Research areas

  1. Chemical synthesis of oligosaccharides.
  2. Chemical synthesis of glycoproteins and glycopeptides.
  3. Elucidation of oligosaccharide function.
  4. Elucidation of plant oligosaccharides.

The oligosaccharides of proteins were previously thought to be involved with protein conformation, dynamics, protein trafficking, and glycoprotein lifetime in the blood. We have examined the synthesis of homogeneous glycoproteins containing a human complex-type oligosaccharide in order to evaluate the function of oligosaccharides. We synthesized several small glycoproteins (40?76 amino acid residues), an erythropoietin analogue (166 amino acid residues), and co-stimulated the glycoprotein of T-cells (120 amino acid residues). To synthesize these glycoproteins, the polypeptide sequences of target glycoproteins were divided into several segments, and these segments were synthesized by solid-phase peptide synthesis. After preparation of both the glycopeptide-thioester and the peptides, the components were coupled by repetitive Native Chemical Ligation (NCL). After construction of the glycosylated polypeptide chain, we performed folding experiments to evaluate the effects of the oligosaccharide on the protein folding process. Folded glycoproteins were structurally analyzed by NMR and CD spectroscopies to evaluate the conformational differences between glycosylated and nonglycosylated proteins. In our laboratory, we pursue elucidation of oligosaccharide functions through the use of such chemical approaches.

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