The University of Osaka · Biochemistry, Genetics and Molecular Biology
Professor Yasuhiro Kajihara's research lab specializes in the chemical synthesis and structural analysis of complex glycans and glycoproteins, with a focus on sialylated oligosaccharides and their biological functions. The lab develops innovative solid-phase synthesis methods and chemoselective ligation techniques to produce homogeneous glycoforms of biologically important proteins such as erythropoietin, enabling detailed structure-function studies. A central theme is the precise construction of glycoproteins with defined glycosylation patterns to unravel the roles of sialic acid in protein stability, solubility, and biological activity.
Figures are computed from collected data and may differ slightly.
Incremental developments in the chemistry of peptides, proteins and carbohydrates have enabled researchers to assemble entire glycoproteins with high precision. Based on sophisticated ligation chemistries pure glycoproteins bearing a single glycosylation pattern have become available. The impact of N-glycosylation on the function of glycoproteins is generally recognized but not well understood. Based on the recent advances in the synthesis of glycoproteins by chemical methods researchers can fin
We describe herein the preparation of 24 pure asparagine-linked oligosaccharides (Asn-oligosaccharides) from asparagine-linked biantennary complex-type sialylundecasaccharide [(NeuAc-alpha-2,6-Gal-beta-1,4-GlcNAc-beta-1,2-Man-alpha-1,6/1,3-)(2)-Man-beta-1,4-GlcNAc-beta-1,4-GlcNAc-beta-1-asparagine, 2] obtained from egg yolk. Our synthetic strategy aimed at adapting branch specific exo-glycosidases digestion (beta-D-galactosidase, N-acetyl-beta-D-glucosaminidase and alpha-D-mannosidase) of the in
New and improved: New reaction conditions for tert-Boc-based solid-phase peptide synthesis make acid-labile sialyloligosaccharyl peptide α-thioesters accessible. To demonstrate this, a sialyloligosaccharyl-erythropoietin glycoform (see picture) with 166 amino acid residues was synthesized.
The role of sialyloligosaccharides on the surface of secreted glycoproteins is still unclear because of the difficulty in the preparation of sialylglycoproteins in a homogeneous form. We selected erythropoietin (EPO) as a target molecule and designed an efficient synthetic strategy for the chemical synthesis of a homogeneous form of five EPO glycoforms varying in glycosylation position and the number of human-type biantennary sialyloligosaccharides. A segment coupling strategy performed by nativ
The substrate specificity and enzymatic sialylation ability of the bacterium α-2,6-sialyltransferase were examined. The enzyme assay displayed a remarkable ability to catalyze sialyl transfer to type-II oligosaccharides possessing fucoside or sialoside at the 2 or 3 position of the terminal galactoside. Enzymatic syntheses were performed in order to confirm the structure of unusual assay products found when using Neu5Ac β2,3Galβ1,4Glc and Fuc α1,2Galβ1,4Glc as the sialyl acceptors. Both sialylat
Neu und verbessert: Neue Reaktionsbedingungen für die tert-Boc-basierte Festphasenpeptidsynthese machen säurelabile Sialyloligosaccharylpeptid-α-thioester zugänglich. Als Beleg wurde eine 166 Aminosäuren umfassende Erythropoietin-Sialyloligosaccharyl-Glycoform (siehe Bild) synthetisiert.
A different route to peptide α-thioesters through a new peptide-bond-cleavage method at a cysteine residue by S-thiocarbonylation and subsequent treatment with N-acetylguanidine is described (see scheme). The resultant peptidyl-N-acetylguanidine can be converted into the corresponding peptide α-thioester and is also usable as an alternative to a peptide α-thioester. This method allows efficient kinetically controlled ligation in the presence of thiols. Detailed facts of importance to specialist
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTEfficient Chemical Synthesis of CMP-Neu5Ac and CMP-(Neu5Ac.alpha.2.fwdarw.8Neu5Ac)Yasuhiro Kajihara, Takashi Ebata, Koshi Koseki, Hisashi Kodama, Hajime Matsushita, and Hironobu HashimotoCite this: J. Org. Chem. 1995, 60, 17, 5732–5735Publication Date (Print):September 1, 1995Publication History Published online1 May 2002Published inissue 1 September 1995https://pubs.acs.org/doi/10.1021/jo00122a076https://doi.org/10.1021/jo00122a076research-articleACS
The glycoprotein quality control (GQC) system in the endoplasmic reticulum (ER) effectively uses chaperone-type enzymes and lectins such as UDP-glucose:glycoprotein glucosyltransferase (UGGT), calnexin (CNX), calreticulin (CRT), protein disulfide bond isomerases (ERp57 or PDIs), and glucosidases to generate native-folded glycoproteins from nascent glycopolypeptides. However, the individual processes of the GQC system at the molecular level are still unclear. We chemically synthesized a series of
UDP-glucose:glycoprotein glucosyltransferase (UGGT) plays a key role in recognizing folded and misfolded glycoproteins in the glycoprotein quality control system of the endoplasmic reticulum. UGGT detects misfolded glycoproteins and re-glucosylates them as a tag for misfolded glycoproteins. A flexible model to reproduce in vitro folding of a glycoprotein in the presence of UGGT in a mixture containing correctly folded, folding intermediates, and misfolded glycoproteins is described. The data dem
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