Xylanase inhibitors bind to nonstarch polysaccharides.
This study is an in-depth investigation of the interaction between polysaccharides and the proteinaceous xylanase inhibitors, Triticum aestivum xylanase inhibitor (TAXI), xylanase inhibitor protein (XIP), and thaumatin-like xylanase inhibitor (TLXI). The binding affinities of all three known types of xylanase inhibitors from wheat are studied by measuring the residual xylanase inhibition activity after incubation of the inhibitors in the presence of different polysaccharides, such as beta-glucans and (arabino)xylans. The binding affinities of all three xylanase inhibitors for (arabino)xylans increased with a decreasing arabinose/xylose ratio (A/X ratio). This phenomenon was observed both with water-extractable and water-unextractable (arabino)xylans. The inhibitors also interacted with different soluble and insoluble beta-glucans. None of the inhibitors tested had the ability to hydrolyze the polysaccharides investigated. The present findings contribute to the unraveling of the function of xylanase inhibitors in nature and to the prediction of the effect of added xylanases in cereal-based biotechnological processes, such as bread making and gluten-starch separation.
Fierens
Ellen
E
Laboratory of Food Chemistry and Biochemistry, Department of Microbial and Molecular Systems, Katholieke Universiteit Leuven, Kasteelpark Arenberg 20, Box 2463, 3001 Leuven, Belgium. ellen.fierens@biw.kuleuven.be
Gebruers
Kurt
K
Courtin
Christophe M
CM
Delcour
Jan A
JA
D043364:Endo-1,4-beta Xylanases / Q000037:antagonists & inhibitors*; D004791:Enzyme Inhibitors / Q000378:metabolism*; D005936:Glucans / Q000378:metabolism; D006868:Hydrolysis; D011134:Polysaccharides / Q000378:metabolism*; D012639:Seeds / Q000737:chemistry; D014908:Triticum / Q000737:chemistry; D014990:Xylans / Q000378:metabolism
D004791:Enzyme Inhibitors; D005936:Glucans; D011134:Polysaccharides; D014990:Xylans; C085118:arabinoxylan; D043364:Endo-1,4-beta Xylanases