Surface Binding Sites (SBSs), Mechanism and Regulation of Enzymes Degrading Amylopectin and α-Limit Dextrins

DOI Web Site Web Site 参考文献81件
  • S. Møller Marie
    Enzyme and Protein Chemistry, Department of Systems Biology, Technical University of Denmark
  • Cockburn Darrell
    Enzyme and Protein Chemistry, Department of Systems Biology, Technical University of Denmark
  • W. Nielsen Jonas
    Department of Biology, University of Copenhagen
  • M. Jensen Johanne
    Enzyme and Protein Chemistry, Department of Systems Biology, Technical University of Denmark
  • B. Vester-Christensen Malene
    Enzyme and Protein Chemistry, Department of Systems Biology, Technical University of Denmark
  • M. Nielsen Morten
    Enzyme and Protein Chemistry, Department of Systems Biology, Technical University of Denmark
  • M. Andersen Joakim
    Enzyme and Protein Chemistry, Department of Systems Biology, Technical University of Denmark
  • Wilkens Casper
    Enzyme and Protein Chemistry, Department of Systems Biology, Technical University of Denmark
  • Rannes Julie
    Enzyme and Protein Chemistry, Department of Systems Biology, Technical University of Denmark
  • Hägglund Per
    Enzyme and Protein Chemistry, Department of Systems Biology, Technical University of Denmark
  • Henriksen Anette
    Protein Chemistry Group, Carlsberg Laboratory
  • Abou Hachem Maher
    Enzyme and Protein Chemistry, Department of Systems Biology, Technical University of Denmark
  • Willemoës Martin
    Department of Biology, University of Copenhagen
  • Svensson Birte
    Enzyme and Protein Chemistry, Department of Systems Biology, Technical University of Denmark

この論文をさがす

説明

Certain enzymes interact with polysaccharides at surface binding sites (SBSs) situated outside of their active sites. SBSs are not easily identified and their function has been discerned in relatively few cases. Starch degradation is a concerted action involving GH13 hydrolases. New insight into barley seed α-amylase 1 (AMY1) and limit dextrinase (LD) includes i) kinetics of bi-exponential amylopectin hydrolysis by AMY1, one reaction having low Km (8 µg/mL) and high kcat (57 s－1) and the other high Km (97 µg/mL) and low kcat (23 s－1). β-Cyclodextrin (β-CD) inhibits the first reaction by binding to an SBS (SBS2) on domain C with Kd = 70 µM, which for the SBS2 Y380A mutant increases to 1.4 mM. SBS2 thus has a role in the fast, high-affinity component of amylopectin degradation. ii) The N-terminal domain of LD, the debranching enzyme in germinating seeds, shows distant structural similarity with domains including CBM21 present in other proteins and involved in various molecular interactions, but no binding site identity. LD is controlled by barley limit dextrinase inhibitor (LDI) which belongs to the cereal-type inhibitor family and forms a tight 1:1 complex with LD. iii) LDI in turn is regulated by disulfide reduction mediated by the barley thioredoxin h (trxh) NADPH-dependent thioredoxin reductase (NTR) system. Based on the progress monitored by released free thiol groups from LDI and its failure to inhibit LD as elicited by trxh, the LDI inactivation is proposed to stem from loss of structural integrity due to reduction of all four disulfides.

収録刊行物

参考文献 (81)*注記

もっと見る

キーワード

詳細情報 詳細情報について

問題の指摘

ページトップへ