Journal of Applied Glycoscience
Online ISSN : 1880-7291
Print ISSN : 1344-7882
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  • Megumi Matsui, Haruka Kono, Makoto Ogata
    2018 Volume 65 Issue 3 Pages 31-36
    Published: August 20, 2018
    Released: August 20, 2018
    [Advance publication] Released: June 12, 2018
    JOURNALS FREE ACCESS FULL-TEXT HTML

    A novel substrate {Galβ1,4GlcNAcβ1,4GlcNAc-β-pNP [Gal(GlcNAc)2-β-pNP]} for assaying lysozyme activity has been designed using docking simulations and enzymatic synthesis via β-1,4-galactosyltransferase-mediated transglycosylation from UDP-Gal as the donor to (GlcNAc)2-β-pNP as the acceptor. Hydrolysis of the synthesized Gal(GlcNAc)2-β-pNP and related compounds using hen egg-white lysozyme (HEWL) demonstrated that the substrate was specifically cleaved to Gal(GlcNAc)2 and p-nitrophenol (pNP). A combination of kinetic studies and docking simulation was further conducted to elucidate the mode of substrate binding. The results demonstrate that Gal(GlcNAc)2-β-pNP selectively binds to a subsite of lysozyme to liberate the Gal(GlcNAc)2 and pNP products. The work therefore describes a new colorimetric method for quantifying lysozyme on the basis of the determination of pNP liberated from the substrate.

  • Tomoya Shintani, Yuhei Kosuge, Hisashi Ashida
    2018 Volume 65 Issue 3 Pages 37-43
    Published: August 20, 2018
    Released: August 20, 2018
    [Advance publication] Released: June 12, 2018
    JOURNALS FREE ACCESS FULL-TEXT HTML

    Glucosamine (GlcN) is commonly used as a dietary supplement to promote cartilage health in humans. We previously reported that GlcN could induce autophagy in cultured mammalian cells. Autophagy is known to be involved in the prevention of various diseases and aging. Here, we showed that GlcN extended the lifespan of the nematode Caenorhabditis elegans by inducing autophagy. Autophagy induction by GlcN was demonstrated by western blotting for LGG-1 (an ortholog of mammalian LC3) and by detecting autophagosomal dots in seam cells by fluorescence microscopy. Lifespan assays revealed that GlcN-induced lifespan extension was achieved with at least 5 mM GlcN. A maximum lifespan extension of approximately 30 % was achieved with 20 mM GlcN (p<0.0001). GlcN-induced lifespan extension was not dependent on the longevity genes daf-16 and sir-2.1 but dependent on the autophagy-essential gene atg-18. Therefore, we suggest that oral administration of GlcN could help delay the aging process via autophagy induction.

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