Trends in Glycoscience and Glycotechnology
Online ISSN : 1883-2113
Print ISSN : 0915-7352
ISSN-L : 0915-7352
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Volume 20, Issue 114
Displaying 1-5 of 5 articles from this issue
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MINIREVIEW
  • Electrochemical Conversion of Thioglycosides to Glycosyl Triflates
    Toshiki Nokami, Akito Shibuya, Jun-ichi Yoshida
    2008 Volume 20 Issue 114 Pages 175-185
    Published: 2008
    Released on J-STAGE: December 03, 2008
    DOIhttps://doi.org/10.4052/tigg.20.175
    JOURNAL FREE ACCESS
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    Glycosyl triflates, which serve as important intermediates in glycosylation reactions, were generated and accumulated by low-temperature electrochemical oxidation of thioglycosides, such as thioglucosides, thiogalactosides, and thiomannosides, in the presence of tetrabutylammonium triflate (Bu4NOTf) as a supporting electrolyte. The solutions of glycosyl triflates thus obtained were then characterized by low-temperature NMR measurements. The thermal stability of glycosyl triflates and their reactions with glycosyl acceptors were also studied.
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  • Development of Novel Glycosyl Donors for 1,2-cis Glycosylation Reaction for Amino Sugar and Synthesis of anti-Helicobacter pylori Oligosaccharide
    Shino Manabe, Kazuyuki Ishii, Yukishige Ito
    2008 Volume 20 Issue 114 Pages 187-202
    Published: 2008
    Released on J-STAGE: December 03, 2008
    DOIhttps://doi.org/10.4052/tigg.20.187
    JOURNAL FREE ACCESS
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    Despite advances in synthetic carbohydrate chemistry, the 1,2-cis-selective glycosylation reaction of 2-deoxy-2-amino sugars has not progressed during the last three decades. For such glycosylations, 2-azide glycosyl donors have been extensively employed, notwithstanding difficulties in their preparation and moderate selectivities. Herein, we report on a highly 1,2-cis-selective trans-carbamate sugar donor, which can be readily prepared in high yields. Furthermore, the utility of the novel cis-selective glycosyl donor for preparing complex oligosaccharides is demonstrated through the effective synthesis of an anti-Helicobacter pylori hexasaccharide.
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  • The study of glycopeptide syntheses: exploring concise O-linked sialylglycopeptide synthesis and glycopeptide coupling reaction
    Ryo Okamoto, Yasuhiro Kajihara
    2008 Volume 20 Issue 114 Pages 203-217
    Published: 2008
    Released on J-STAGE: December 03, 2008
    DOIhttps://doi.org/10.4052/tigg.20.203
    JOURNAL FREE ACCESS
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    For the preparation of both N-linked and O-linked sialylglycopeptides and their glycoprotein form, the critical points in these syntheses are the preparation of an appropriate amount of sialyloligosaccharyl-amino acid and isolation of the sialylglycopeptides. In particular, it have been difficult to isolate O-linked sialylglycopeptides in which the sialyl linkage is labile to acid treatment and the N-acetyl-galactosaminyl linkage is labile to base-treatment. For the preparation of target glycoproteins by the use of such sialylglycopeptide thus obtained, an efficient coupling method should be essential. In this review, we introduce our new sialyl donors for the synthesis of sialyl-TN epitope and O-linked sialyl-TN-glycopeptides, and a new concept for a glycopeptide coupling reaction in the synthesis of glycoproteins.
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GLYCODEBUT
  • The role of ErbB3 N-glycan in dimer formation: Implications for transforming activity
    Shunichi Yokoe
    2008 Volume 20 Issue 114 Pages 219-225
    Published: 2008
    Released on J-STAGE: December 03, 2008
    DOIhttps://doi.org/10.4052/tigg.20.219
    JOURNAL FREE ACCESS
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    The ErbB2/ErbB3 heterodimer elicits potent mitogenic and transforming signals, and clinical studies indicate that these receptors play an important role in tumor incidence and progression. In this study, a series of human ErbB3 mutants devoid of N-glycans expressed in Flp-In-CHO cells were used to determine whether N-glycosylation is involved in the function of ErbB3. A crosslinking study showed that the Asn418 to Gln mutant (N418Q) of ErbB3 underwent heregulin (HRG)-independent autodimerization. Furthermore, ErbB3-N418Q autodimerized with ErbB2 in the absence of HRG, and receptor tyrosine phosphorylation and subsequent extracellular signal-regulated kinase (ERK) and Akt phosphorylation were promoted. A cell proliferation assay and a soft agar colony formation assay demonstrated that ErbB2/ErbB3-N418Q co-expression promoted cell proliferation and colony formation in soft agar in ERK- and Akt-dependent manners. ErbB2/ErbB3-N418Q co-expression also promoted the growth of tumors in athymic nude mice when injected subcutaneously. These results suggest that the Asn418-linked N-glycan in ErbB3 plays a crucial role in regulating receptor dimer formation and transforming activity.
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GLYCOTOPICS
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