Arabinoxylan Solubilization and Inhibition of the Barley Malt Xylanolytic System by Wheat During Mashing with Wheat Wholemeal Adjunct: Evidence for a New Class of Enzyme Inhibitors in Wheat

Debyser, Winok; Derdelinckx, Guy; Delcour, Jan A.

doi:10.1094/asbcj-55-0153

Cited by 70 publications

(64 citation statements)

References 14 publications

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“…To allow detection of eventually truncated N-and C-termini, the custom database was subsequently N-and C-terminally 'ragged' using DBToolkit prepared by spotting 1 µl of a mixture of sample and matrix (7 mg/ml CHCA in 50% ACN containing 0.1% TFA) on a stainless steel (192-well) MALDI target plate and allowed to air-dry at RT. Prior to MALDI-MS analysis, the instrument was externally calibrated with a mixture of Angiotensin I, Glu-fibrino-peptide B, ACTH (1)(2)(3)(4)(5)(6)(7)(8)(9)(10)(11)(12)(13)(14)(15)(16)(17), and ACTH (18-39). For MS/MS experiments, the instrument was externally calibrated with fragments of Glu-fibrino-peptide.…”

Section: Protein Identification By Tandem Mass Spectrometric Analysismentioning

confidence: 99%

Variability of polymorphic families of three types of xylanase inhibitors in the wheat grain proteome

et al. 2008

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Cereals contain proteinaceous inhibitors of endo-β-1,4-xylanases (E.C.3.2.1.8, xylanases). Since these xylanase inhibitors (XIs) are only active against xylanases of microbial origin and do not interact with plant endogenous xylanases, they are believed to act as a defensive barrier against phytopathogenic attack. So far, three types of XIs have been identified, i.e. Triticum aestivum XI (TAXI), xylanase inhibiting protein (XIP), and thaumatin-like XI (TLXI) proteins. In this study the variation in XI forms present in wheat grain was elucidated using high-resolution 2-DE in combination with LC-ESI-MS/MS and biochemical techniques. Reproducible 2-DE fingerprints of TAXI-, XIP-, and TLXI-type XIs, selectively purified from whole meal of three European wheat cultivars using cation exchange chromatography (CEC) followed by affinity chromatography (AC), were obtained using a pH-gradient of 6 to 11 and a molecular mass range of 10 to 60 kDa. Large polymorphic XI families, not known to date, which exhibit different pI-and/or molecular mass values, were visualised by colloidal CBB staining. Identification of distinct genetic variants by MS/MS-analysis provides a partial explanation for the observed XI heterogeneity.Besides genetic diversity, PTMs, such as glycosylation, account for the additional complexity of the 2-DE patterns.2

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Section: Protein Identification By Tandem Mass Spectrometric Analysismentioning

confidence: 99%

Variability of polymorphic families of three types of xylanase inhibitors in the wheat grain proteome

et al. 2008

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“…They are nowadays often present in bread improvers, as they beneficially affect bread volume and processability of doughs [2]. They can also be applied in beer production [3], animal feeds [4] and wheat glutenstarch separation processes [5,6]. The majority of the xylanases belong either to glycoside hydrolase family 10 (GH10) or to the structurally unrelated glycoside hydrolase family 11 (GH11) [7].…”

Section: Introductionmentioning

confidence: 99%

Biochemical and structural characterization of TLXI, the Triticum aestivum L. thaumatin-like xylanase inhibitor

Fierens

Gebruers

Voet

et al. 2009

Journal of Enzyme Inhibition and Medicinal Chemistry

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Thaumatin-like xylanase inhibitors (TLXI) are recently discovered wheat proteins. They belong to the family of the thaumatin-like proteins and inhibit glycoside hydrolase family 11 endoxylanases commonly used in different cereal based (bio)technological processes. We here report on the biochemical characterisation of TLXI. Its inhibition activity is temperature-and pH-dependent and shows a maximum at approximately 408C and pH 5.0. The TLXI structure model, generated with the crystal structure of thaumatin as template, shows the occurrence of five disulfide bridges and three b-sheets. Much as in the structures of other short-chain thaumatin-like proteins, no a-helix is present. The circular dichroism spectrum of TLXI confirms the absence of a-helices and the presence of antiparallel b-sheets. All ten cysteine residues in TLXI are involved in disulfide bridges. TLXI is stable for at least 120 min between pH 1-12 and for at least 2 hours at 1008C, making it much more stable than the other two xylanase inhibitors from wheat, i.e. Triticum aestivum xylanase inhibitor (TAXI) and xylanase inhibitor protein (XIP). This high stability can probably be ascribed to the high number of disulfide bridges, much as seen for other thaumatin-like proteins.

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“…In the last decade, three structurally different types of proteinaceous inhibitors of these enzymes were discovered in wheat: TAXI-(Triticum aestivum xylanase inhibitor) [9,10], XIP-(xylanase inhibitor protein) [11] and TLXI-(thaumatin-like xylanase inhibitor) type inhibitors [12]. The practical significance of inhibition in several cereal-based processes has been reviewed [13].…”

Section: Introductionmentioning

confidence: 99%

His22 of TLXI plays a critical role in the inhibition of glycoside hydrolase family 11 xylanases

Rombouts

Fierens

Vandermarliere

et al. 2008

Journal of Enzyme Inhibition and Medicinal Chemistry

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Recently, a novel wheat thaumatin-like protein, TLXI, which inhibits microbial glycoside hydrolase family (GH) 11 xylanases has been identified. It is the first xylanase inhibitor that exerts its inhibition in a non-competitive way. In the present study we gained insight into the interaction between TLXI and xylanases via combined molecular modeling and mutagenic approaches. More specifically, site-specific mutation of His22, situated on a loop which distinguishes TLXI from other, non-inhibiting, thaumatin-like proteins, and subsequent expression of the mutant in Pichia pastoris resulted in a protein lacking inhibition capacity. The mutant protein was unable to form a complex with GH11 xylanases. Based on these findings, the interaction of TLXI with GH11 xylanases is discussed.

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Arabinoxylan Solubilization and Inhibition of the Barley Malt Xylanolytic System by Wheat During Mashing with Wheat Wholemeal Adjunct: Evidence for a New Class of Enzyme Inhibitors in Wheat

Cited by 70 publications

References 14 publications

Variability of polymorphic families of three types of xylanase inhibitors in the wheat grain proteome

Variability of polymorphic families of three types of xylanase inhibitors in the wheat grain proteome

Biochemical and structural characterization of TLXI, the Triticum aestivum L. thaumatin-like xylanase inhibitor

His22 of TLXI plays a critical role in the inhibition of glycoside hydrolase family 11 xylanases

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