Cross-inhibitory activity of cereal protein inhibitors against α-amylases and xylanases

Ana I. Sancho, Craig B. Faulds, Birte Svensson, Begoña Bartolomé, Gary Williamson, Nathalie Juge

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33 Citations (Scopus)

Abstract

The purification and characterisation of a xylanase inhibitor (XIP-I) from wheat was reported previously. In our current work, XIP-I is also demonstrated to have the capacity to inhibit the two barley α-amylase isozymes (AMY1 and AMY2). XIP-I completely inhibited the activity of AMY1 and AMY2 towards insoluble Blue Starch and a soluble hepta-oligosaccharide derivative. A ternary complex was formed between insoluble starch, a catalytically inactive mutant of AMY1 (D180A), and XIP-I, suggesting that the substrate-XIP-I interaction is necessary for inhibition of barley α-amylases. Ki values for α-amylase inhibition, however, could not be calculated due to the nonlinear nature of the inhibition pattern. Furthermore, surface plasmon resonance and gel electrophoresis did not indicate interaction between XIP-I and the α-amylases. The inhibition was abolished by CaCl2, indicating that the driving force for the interaction is different from that of complexation between the barley α-amylase/subtilisin inhibitor (BASI) and AMY2. This is the first report of a proteinaceous inhibitor of AMY1. BASI, in addition, was demonstrated to partially inhibit the endo-1,4-β-D-xylanase from Aspergillus niger (XylA) of glycoside hydrolase family 11. Taken together, the data demonstrate for the first time the dual target enzyme specificity of BASI and XIP-I inhibitors for xylanase and α-amylase.

Original languageEnglish
Pages (from-to)136-144
Number of pages9
JournalBBA Proteins and Proteomics
Volume1650
Issue number1-2
DOIs
Publication statusPublished - 21 Aug 2003
Externally publishedYes

Keywords

  • Barley α-amylase isozyme
  • Protein-carbohydrate interaction
  • Proteinaceous inhibitor
  • Substrate-dependent inhibitor binding
  • Xylanase

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