Acetobacter capsulatum ATCC 11894株の産生する菌体外デキストリンデキストラナーゼの速度論的解析 A Kinetic Study of an Extracellular Dextrin Dextranase from Acetobacter capsulatum ATCC 11894

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Abstract

Acetobacter capsulatum ATCC 11894株の産生する菌体外デキストリンデキストラナーゼ(DDase:EC2.4.1.2)を用い,各種マルトデキストリンを基質とした場合の,デキストラン合成反応を速度論的に解析した.各種マルトデキストリンに対するDDaseの反応速度論量(Km,Vmax,Ki,Ks)が測定された.各種マルトオリゴ糖のグルコース残基のデキストランへの変換効率は,基質重合度の上昇とともに増加し,短鎖アミロースからデキストランへの変換率は約74%であった.各種マルトオリゴ糖を基質とした場合,デキストラン合成反応はマルトースにより顕著な阻害を受けた.その阻害形式は混合型を示し,マルトース分子はグルコシル基受容体にもなりうることが判明した.そこで,グルコシル基受容体にマルトースを用い,その際生成される各種オリゴ糖を単離・精製し,それらの化学構造を1H一および13C-NMRにより解析した.一連の精製グルコオリゴ糖の化学構造は,それぞれ4-O-α-isomaltosyl-D-glucose, 4-O-α -isomaltotriosyl-D-glu-cose,4-O-α-isomaltotetraosyl-D-glucose,4-O-α-isomalto-pentaosyl-D-glucoseおよび4-O-α-isomaltohexaosyl-D-glucoseと同定された.

The kinetic studies of an extracellular dextrin dextranase (DDase, EC 2.4.1.2) from Acetobacter capsulatum ATCC 11894 were performed by using a series of maltooligosaccharides (DP= 3-7) and short-chain amylose (DP=17.3). The kinetic parameters (Km, Vmax, Ki and Ks) of DDase for the above maltodextrins were first determined. The conversion rates from various maltodextrins into dextran increased with the increase in the DP number of donor substrates. The maximum yield of product dextran reached about 74% by using short-chain amylose as the substrate. The dextran synthesis reaction by DDase was strongly inhibited by maltose. The mode of inhibition of dextran synthesis by DDase action was mixed. From the inhibition studies of DDase, maltose molecules were definitely able to be glucosyl group acceptors. Therefore, various oligosaccharides were able to be formed from a high concentration of maltose as glucosyl group acceptors. The oligosaccharides formed were separated, purified and analyzed by 1H-and 13C-NMR. The chemical structures of the purified glucooligosaccharides were identified as 4-O-α-isomaltosyl-D-glucose, 4-O-α-isomal-totriosyl-D-glucose, 4-O -α-isomaltotetraosyl-D-glucose, 4-O-α-isomaltopentaosyl-D-glucose and 4-O-α-isomaltohexaosyl-D-glucose.

Journal

  • Journal of Applied Glycoscience

    Journal of Applied Glycoscience 47(1), 27-33, 2000-03-31

    The Japanese Society of Applied Glycoscience

References:  9

Codes

  • NII Article ID (NAID)
    10008251447
  • NII NACSIS-CAT ID (NCID)
    AN10453916
  • Text Lang
    ENG
  • Article Type
    ART
  • ISSN
    13403494
  • NDL Article ID
    5397172
  • NDL Source Classification
    ZP24(科学技術--化学・化学工業--糖・澱粉)
  • NDL Call No.
    Z17-15
  • Data Source
    CJP  NDL  J-STAGE  JASI 
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