A novel class of protein from wheat which inhibits xylanases

W. Russell McLauchlan, Maria T. Garcia-Conesa, Gary Williamson, Martinus Roza, Peter Ravestein, Jan Maat

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170 Citations (Scopus)


We have purified a novel class of protein that can inhibit the activity of endo-β-1,4-xylanases. The inhibitor from wheat (Triticum aestivum, var. Soisson) is a glycosylated, monomeric, basic protein with a pI of 8.7-8.9, a molecular mass of 29 kDa and a unique N-terminal sequence of AGGKTGQVTVFWGRN. We have shown that the protein can inhibit the activity of two family-11 endo-β-1,4-xylanases, a recombinant enzyme from Aspergillus niger and an enzyme from Trichoderma viride. The inhibitory activity is heat and protease sensitive. The kinetics of the inhibition have been characterized with the A. niger enzyme using soluble wheat arabinoxylan as a substrate. The K(m) for soluble arabinoxylan in the absence of inhibitor is 20 ± 2 mg/ml with a k(cat) of 103 ± 6 s-1. The kinetics of the inhibition of this reaction are competitive, with a K(i) value of 0.35 μM, showing that the inhibitor binds at or close to the active site of free xylanase. This report describes the first isolation of a xylanase inhibitor from ally organism.

Original languageEnglish
Pages (from-to)441-446
Number of pages6
JournalBiochemical Journal
Issue number2
Publication statusPublished - 1 Mar 1999
Externally publishedYes


  • Arabinoxylan
  • Glycosyl hydrolase
  • Protein-protein interaction
  • Triticum aestivum
  • Xylanase inhibitor

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