The Multisubstrate Specificity and the Quaternary Structure of Cyclodextrin-/Pullulan-degrading Enzymes

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Author(s)

    • Park Kwan Hwa PARK Kwan Hwa
    • Research Center for New Bio-Materials in Agriculture and Department of Food Science and Technology, School of Agricultural Biotechnology, Seoul National University

Abstract

Multiple amino acid sequence alignment and crystal structures of cyclodextrin (CD)-/pullulandegrading enzymes revealed the presence of an N-terminal extension of approximately 130 residuesnot found in ordinary α-amylases. Based on the results obtained from size exclusion chromatogra-phy and sedimentation equilibrium ultracentrifugation experiments, most of these enzymes aremainly in monomer-dimer-tetramer or monomer-dimer-dodecamer equilibrium and the unique Nterminal domain contributes to the formation of oligomeric state in this group of enzymes. Thestudies on the oligomerization and activity of the CD-/pullulan-degrading enzymes indicated thatthere was a significant correlation between the presence of monomer-dimer equilibrium and enzymatic activity. They also suggested that both the monomer and dimer were enzymatically active, but with different substrate preference for fl-CD and starch. The substrate preference of a dimerfor fl-CD was interpreted from the geometry of the active site in the homodimer, that is, small andcompact substrate molecules such as fl-CD might effectively access to the deep and narrow activesite of the dimeric enzyme. Therefore, it was suggested that the monomer-dimer equilibrium present in the reaction mixture reflected different multisubstrate specificity of CD-/pullulan-degrading Multiple amino acid sequence alignment and crystal structures of cyclodextrin (CD)-/pullulan degrading enzymes revealed the presence of an N-terminal extension of approximately 130 residues not found in ordinary α-amylases. Based on the results obtained from size exclusion chromatography and sedimentation equilibrium ultracentrifugation experiments, most of these enzymes are mainly in monomer-dimer-tetramer or monomer-dimer-dodecamer equilibrium and the unique Nterminal domain contributes to the formation of oligomeric state in this group of enzymes. The studies on the oligomerization and activity of the CD-/pullulan-degrading enzymes indicated that there was a significant correlation between the presence of monomer-dimer equilibrium and enzymatic activity. They also suggested that both the monomer and dimer were enzymatically active, but with different substrate preference for β-CD and starch. The substrate preference of a dimer for β-CD was interpreted from the geometry of the active site in the homodimer, that is, small and compact substrate molecules such as fl-CD might effectively access to the deep and narrow activesite of the dimeric enzyme. Therefore, it was suggested that the monomer-dimer equilibrium present in the reaction mixture reflected different multisubstrate specificity of CD-/pullulan-degrading enzymes.

Journal

  • Journal of Applied Glycoscience

    Journal of Applied Glycoscience 48(3), 293-299, 2001-07-01

    The Japanese Society of Applied Glycoscience

References:  36

Cited by:  2

Codes

  • NII Article ID (NAID)
    10008252941
  • NII NACSIS-CAT ID (NCID)
    AN10453916
  • Text Lang
    ENG
  • Article Type
    Journal Article
  • ISSN
    13403494
  • NDL Article ID
    5831569
  • 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 
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