サイクロデキストリン合成酵素の潜在性反応および反応生成物デキストランの特性 Further Characterization of Dormant Reaction of Cyclodextrin Glucanotransferase with Dextran and Subsequently Produced Dextran

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Author(s)

Abstract

サイクロデキストリン合成酵素(CGTase)をクリニカルデキストランに作用させると,構造の変化したデキストランが得られた.この反応は起源の異なるCGTaseでも確認され,反応に伴う還元力の生成は少ないが,生成物デキストランの分子量分布に大きな違いが見出された.生成物デキストランはCon Aや蛍光試薬,トルイジノナフタレンスルホン酸との相互作用が増加したが,イソアミラーゼとグルコアミラーゼによる被分解性はCGTase作用時の反応温度により大きく異なることがわかった.HMQCによる2次元NMRでは,CGTase作用前後のデキストランのスペクトルに明瞭な差異が認められた.この変化とメチル化分析との結果を総合すると,生成物デキストランには,新たにa-1,4-グルコシド結合を含む分岐構造が生成していることが示唆された.

Structurally modified dextran was produced by the action of cyclodextrin glucanotransferase (CGTase) on clinical dextran. The dormant activity of CGTase was further confirmed by using the enzyme preparation from a different source. Although an increase in reducing sugar in the reaction mixture was small, a clear difference in the molecular weight distribution of CGTase-treated dextran was observed, as in previous experiments. Therefore the susceptibility of CGTases on dextran was verified with the other origin of CGTase. CGTase-treated dextran showed a higher interaction with Con A and fluorescent reagent, 6-p-toluidinylnaphthalene-2-sulfonate. The susceptibility of CGTasetreated dextran to isoamylase and glucoamylase varied significantly according to the reaction temperatures for the CGTase action. NMR-HMQC and methylation analyses both indicated additional occurrence of α-1, 4-branch points in the dextran molecule, which opposed the knowledge of sole branch point of -1, 3-linkages in the dextran. CGTase action seemed to increase the content of α-1, 4-branch points in the CGTase- treated dextran by introducing the cleaved fragments as the new branch into the back bones of α-1, 6-linkages. These results suggested that CGTasetreated dextran had increasing amounts of α-1, 4-branch points, which caused the structural changes demonstrated by the above analysis.

Journal

  • Journal of Applied Glycoscience

    Journal of Applied Glycoscience 46(3), 265-271, 1999-08-31

    The Japanese Society of Applied Glycoscience

References:  17

Cited by:  1

Codes

  • NII Article ID (NAID)
    10008259204
  • NII NACSIS-CAT ID (NCID)
    AN10453916
  • Text Lang
    ENG
  • Article Type
    Journal Article
  • ISSN
    13403494
  • NDL Article ID
    4846195
  • 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  CJPref  NDL  J-STAGE  JASI 
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