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HvXI: An endoxylanase inhibitor from barley. H. GOESAERT (1), W. Debyser (1), K. Gebruers (1),
and J. A. Delcour (1). (1) Laboratory of Food Chemistry, Katholieke Universiteit Leuven.
An endoxylanase inhibitor with a protein structure was purified to
homogeneity from barley (Hordeum vulgare L.). HvXI (Hordeum vulgare L. xylanase
inhibitor) is a non-glycosylated monomeric protein, with a molecular mass of ca. 40 kD and a pI of 9.3 or
higher. While it inhibits different endoxylanases to a varying degree, the activities of an
alpha-L-arabinofuranosidase and a beta-D-xylosidase were not inhibited. Other characteristics and optimal
conditions for inhibition were also studied. Apparently, the inhibitor occurs in two molecular forms. These
characteristics and the N-terminal sequences of the composing polypeptides show that the barley inhibitor is
homologous with TAXI (Triticum aestivum L. xylanase inhibitor), an endoxylanase inhibitor from
wheat flour (Debyser et al., 1999, J Cereal Sci, 30: 39-43).
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