TY - JOUR. T1 - O-Acetylation of glucuronoxylan in Arabidopsis thaliana wild type and its change in xylan biosynthesis mutants. AU - Chong, S L. AU - Virkki, L. AU - Maaheimo, Hannu. AU - Juvonen, M. AU - Derba-Maceluch, M. AU - Koutaniemi, S. AU - Roach, M. AU - Sundberg, B. AU - Tuomainen, P. AU - Mellerowicz, E J. AU - Tenkanen, M. PY - 2014. Y1 - 2014. N2 - O-Acetylglucuronoxylans (AcGX) in Arabidopsis thaliana carry acetyl residues on the 2-O and/or 3-O positions of the xylopyranosyl (Xylp) units, but the distribution of different O-acetylated Xylp units is partly unclear. We studied a possible correlation of xylan acetylation and the activities of different glycosyltransferases involved in xylan biosynthesis by analyzing the distribution of O-acetyl substituents on AcGX from Arabidopsis wild-type and mutants irx7, irx9-1, irx10, irx14 and gux1gux2. The relative contents of the Xylp structural units were determined with quantitative two-dimensional heteronuclear single quantum coherence ...
Xyloglucan Oligosaccharides. For use in research, biochemical enzyme assays and analytical applications. Purchase Xyloglucan Oligosaccharides.
Purchase high Purity Wheat Arabinoxylan (enzyme debranched 30% Ara) for use in research, biochemical enzyme assays and in vitro diagnostic analysis.
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TY - JOUR. T1 - Combination of internal and external plasticization of hydroxypropylated birch xylan tailors the properties of sustainable barrier films. AU - Mikkonen, Kirsi S.. AU - Laine, Christiane. AU - Kontro, Inkeri. AU - Talja, Riku A.. AU - Serimaa, Ritva. AU - Tenkanen, Maija. N1 - Project code: 76880 PY - 2015. Y1 - 2015. N2 - To develop functional and sustainable products from future wood biorefineries, birch kraft pulp xylan was alkali-extracted and modified in aqueous solvent with hydroxypropylation to enhance its processability to films. For the first time, the roles of internal vs. external plasticization in the mechanical, thermal, and barrier performance of xylan films were systematically evaluated as a function of the degree of substitution (DS) of hydroxypropyl (HP) groups (internal plasticizer) and the added sorbitol (external plasticizer). In addition, the moisture uptake and the degree of crystallinity of hydroxypropyl xylan (HPX) films were characterized. Internal ...
Arabinoxylan gels exhibiting different rheological and lycopene transport properties were obtained by modifying the polysaccharide concentration from 3 to 4% (w/v). The apparent lycopene diffusion coefficient decreased from 2.7 × 10−7 to 2.4 × 10−7 cm2/s as the arabinoxylan concentration in the gel changed from 3 to 4% (w/v). A low amount of lycopene is released by diffusion from arabinoxylan gels. These results indicate that arabinoxylan gels could be carriers for lycopene delivery in specific sites after network degradation. The possibility to modulate lycopene release from arabinoxylan gels makes these biomaterials potential candidates for the controlled delivery of biomolecules.
Xylan, comprising a xylose backbone with substituted sugar units, is the most abundant hemicellulose of secondary cell walls of higher plants, where its interactions with lignin and cellulose confer structural rigidity to the cell wall. Understanding the lignin-xylan interactions may enable development of plants with novel cell wall characteristics, potentially beneficial for production of pulp and chemicals. In this work, fungal xylan-degrading enzymes, including FC1, DFC2 and DFC4 were targeted for introduction into Arabidopsis thaliana and aspen under control of the wood specific promoter to investigate their effect on xylan structure and lignin-xylan interactions. Furthermore, a signal peptide of a secreted cellulase was fused to enzymes sequences in FC1 at N-terminus for targeting of recombinant enzymes to the cell wall whereas other constructs used native fungal SP. GUS reporter staining assay of hybrid aspen showed that the promoter used exhibits wood specific expression. Confocal ...
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In molecular biology, the xyloglucan endo-transglycosylase (XET) is an enzyme that is involved in the metabolism of xyloglucan, which is a component of plant cell walls. This enzyme is part of glycoside hydrolase family 16. Xyloglucan endo-transglycosylase (XET) is thought to be highly important during seed germination, fruit ripening, and rapid wall expansion. Xyloglucan is the predominant hemicellulose in the primary cell walls of most dicotyledons. With cellulose, it forms a network that strengthens the cell wall. XET catalyses the splitting of xyloglucan chains and the linking of the newly generated reducing end to the non-reducing end of another xyloglucan chain, thereby loosening the cell wall. Baumann MJ, Eklöf JM, Michel G, Kallas AM, Teeri TT, Czjzek M, et al. (2007). "Structural evidence for the evolution of xyloglucanase activity from xyloglucan endo-transglycosylases: biological implications for cell wall metabolism". Plant Cell. 19 (6): 1947-63. doi:10.1105/tpc.107.051391. PMC ...
Xylan is one of most abundant polymer after cellulose. However, its potential has yet to be completely recognized. Corn cobs contain a considerable reservoir of xylan. The aim of this work was to study some of the biological activities of xylan obtained from corn cobs after alkaline extraction enhanced by ultrasonication. Physical chemistry and infrared analyses showed 130 kDa heteroxylan containing mainly xylose:arabinose: galactose:glucose (5.0:1.5:2.0:1.2). Xylan obtained exhibited total antioxidant activity corresponding to 48.5 mg of ascorbic acid equivalent/g of xylan. Furthermore, xylan displayed high ferric chelating activity (70%) at 2 mg/mL. Xylan also showed anticoagulant activity in aPTT test. In antimicrobial assay, the polysaccharide significantly inhibited bacterial growth of Klebsiella pneumoniae. In a test with normal and tumor human cells, after 72 h, only HeLa tumor cell proliferation was inhibited (p | 0.05) in a dose-dependent manner by xylan, reaching saturation at around 2 mg/mL,
Primary and secondary walls contain cellulose, hemicellulose and pectin, albeit in different proportions. Approximately equal amounts of pectin and hemicellulose are present in dicot primary walls whereas hemicellulose is more abundant in grasses (e.g., switchgrass). The secondary walls of woody tissue and grasses are composed predominantly of cellulose, lignin, and hemicellulose (xylan, glucuronoxylan, arabinoxylan, or glucomannan). The cellulose fibrils are embedded in a network of hemicellulose and lignin. Cross-linking of this network is believed to result in the elimination of water from the wall and the formation of a hydrophobic composite that limits accessibility of hydrolytic enzymes and is a major contributor to the structural characterisitics of secondary walls.. Xylan, which accounts for up to 30% of the mass of the secondary walls in wood and grasses contributes to the recalcitrance of these walls to enzymic degradation. A high xylan content in wood pulp increases the economic and ...
This thesis presents the application of different protein engineering methods on enzymes and non-catalytic proteins that act upon xyloglucans. Xyloglucans are polysaccharides found as storage polymers in seeds and tubers, and as cross-linking glucans in the cell wall of plants. Their structure is complex with intricate branching patterns, which contribute to the physical properties of the polysaccharide including its binding to and interaction with other glucans such as cellulose.. One important group of xyloglucan-active enzymes is encoded by the GH16 XTH gene family in plants, including xyloglucan endo-transglycosylases (XET) and xyloglucan endo-hydrolases (XEH). The molecular determinants behind the different catalytic routes of these homologous enzymes are still not fully understood. By combining structural data and molecular dynamics (MD) simulations, interesting facts were revealed about enzyme-substrate interaction. Furthermore, a pilot study was performed using structure-guided ...
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The Beechwood Elementary School is a midsized, urban, public school located in the Beechview neighborhood of Pittsburgh, Pennsylvania. The building was built in 1908. It was listed on the National Register of Historic Places in 1986.[1] The school provides taxpayer funded preschool through 5th grade in 2011. Enrollment was 359 in 2011. Students who qualify for free or reduced lunch: 71.08%. Enrollment was 415 in 2010 with 22 teachers employed.[3] The school is part of the Pittsburgh School District.. ...
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Citation: Kiszonas, A.M., Fuerst, E.P., Morris, C.F. 2013. Wheat arabinoxylan structure provides insight into function. Cereal Chemistry. 90:387-395. Interpretive Summary: Arabinoxylans have a unique structure, which contributes to their important function in plant physiology and end-use quality. The complex and heterogeneous structure leads to two very diverse fractions based on water extractability. These two fractions, WEAX and WUAX, differ in their physical properties with respect to arabinose substitution and molecular weight. This results in varied influence on end-use quality. The genetic and environmental influences on arabinoxylan molecules does not conclusively suggest complete genetic or environmental control over the abundance or structure of the molecules. Because of these varied results across many studies, and the highly variable nature of arabinoxylan influence over end-use quality, there is a wealth of research that may still be undertaken to further understand the complex ...
At the most basic level, xylan is composed of differing numbers of xylose sugars, with zero, one or two arabinose side-chains. The xylans in cereal grains tend to contain high numbers of arabinose side-chains (making them highly substituted) with significant differences occurring between cereal varieties, across growing seasons and from one location to another.. The more highly substituted a xylan is, the more water-soluble it tends to become, and the greater the negative impact on digesta viscosity (caused by high levels of soluble long-chain xylans). The level of substitution also influences where any cleaving of the xylose backbone by a xylanase enzyme can take place.. It is a good example of how key xylanase characteristics dictate both how and where the enzyme can act, as well as the end-products subsequently produced. For example, endo-acting xylanases cleave the xylose backbone mid-chain, whilst exo-acting xylanases release free xylose or arabinose sugars from the ends. Even within ...
TonB-dependent receptors (TBDTs) are outer membrane proteins mainly known for the active transport of iron siderophore complexes in Gram-negative bacteria. Analysis of the genome of ,i,Xanthomonas,/i, species revealed an overrepresentation of these transporters. This overrepresentation is associated with the ability to exploit plant carbohydrate and we proposed the existence of specific carbohydrate utilisation systems with TBDTs (named CUT systems). Recently, we identified a CUT system involved in the utilisation of xylan, a major component of plant cell wall and the second most abundant plant polysaccharide in nature. This CUT system encompasses genes required for the degradation of xylan as well as genes for the transport and metabolism of xylo-oligosaccharides, xylose and glucuronate. Interestingly, these genes which expression is induced by xylo-oligosaccharides, are required for optimal growth on plant leaves. Part of the xylanolytic machinery of ,i,Xanthomonas,/i,, including TBDT genes, ...
The structures of hepta- to tetradeca-saccharides, generated by digestion of wheat-endosperm arabinoxylan with endo-(1-,4)-beta-D-xylanase, and isolated by gel-permeation chromatography on Bio-Gel P-6 and high-performance anion-exchange chromatography with pulsed amperometric detection (h.p.a.e.-p.a.d.), were elucidated using monosaccharide and methylation analysis, f.a.b.-m.s., and 1H-n.m.r. spectroscopy. The structures identified had two branching elements, -,4)[alpha-L-Araf-(1-,3)]-beta-D-Xylp-(1-, ... read more and/or -,4)[alpha-L-Araf-(1-,2)][alpha-L-Araf-(1-,3)]-beta-D-Xylp-(1-,, directly connected to each other in all four possible combinations. The h.p.a.e.-p.a.d. elution pattern showed that these combinations are not present in equal amounts. Also, compounds containing two 2,3-branched beta-D-Xylp residues separated by one or two unbranched beta-D-Xylp residues were found, and the presence of a tetradecasaccharide containing three 2,3-branched beta-D-Xylp residues was established. show ...
To find genes important for grass xylan biosynthesis, Ronald, Scheller and their co-authors focused on the GT61 family of glycosyltransferases. GT61 enzymes have been identified through bioinformatics as being expanded in grasses and containing grass-specific subgroups. Working with rice plants, the standard plant model for studying grasses, they conducted a reverse genetics screen of 14 genes with insertional rice mutants that are highly expressed members of the GT61 family. This led them to the identification of a mutant plant they named xax1 because its mutation resulted in the function of the XAX1 being knocked-out ...
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One important market for xylanases is the industrial production of xylooligosaccharides (XOs), small oligomers constituted by 2-10 units of xylan monomers. They can be produced through the enzymatic hydrolysis of xylan catalyzed by an endoxylanase, avoiding the co-production of xylose. The high cost of the enzymatic process may be decreased by using immobilized and stabilized enzymes. In this study, XynA, a recombinant enzyme from B. subtillis, was immobilized in three different supports: agarose and chitosan activated with glyoxyl groups and chitosan activated with glutaraldehyde. High immobilization yields were obtained, 100% for agarose-glyoxyl and chitosan-glutaraldehyde, 82% for chitosan-glyoxyl, with recovered activities of 42.7% (±1.3), 10.7 ± 0.8 %. and 53.6 % (± 1.7), respectively. A great increase in the thermal stability of the enzyme (at 56°C, pH 5.5) was achieved for the glyoxyl derivatives: 75-fold for chitosan and 8600-fold for agarose. The great thermal stability obtained to ...
Buy high purity insoluble AZCL-Xylan (Birchwood) for identification of enzyme activities in research, microbiological enzyme assays in vitro diagno...
Releases reducing sugars from birchwood xylan (X0502), also catalyzes the hydrolysis of 4-methylumbelliferyl-β-D-cellobioside and 4-methylumbelliferyl-β-D-glucopyranosi
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Modules of approx. 120-130 residues displaying structural similarities to CBM6 modules. The only CBM36 currently characterised, that from Paenbacillus polymyxa xylanase 43A, shows calcium-dependent binding of xylans and xylooligosaccharides. X-ray crystallography shows that there is a direct interaction between calcium and ligand ...
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List of words make out of Hemicellulose. Anagrams and Words made out of Hemicellulose. Find Scrabble Point of Hemicellulose. Definition of Hemicellulose. Puzzle Solver.
This assay measures the release of reducing sugars (including xylose and arabinose) during the enzymatic treatment of xylan. If you have reducing sugars (e.g. glucose) in your media, it will also be detected, so you will always have to compare to a control culture with no xylanase ...
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Date: Sat, 18 Apr 1998 02:33:45 +0100 From: Mort OSullivan ,tarwater at brew-master.com, Subject: Beta Glucanases Ray Estrella writes about an enzyme complex sent to him by SAF-ISIS: ,It is called SAFIZYM PTN-L, it is an enzymatic complex that displays ,strengthened Xylanase activities. (Endoglucanases, cellbiohydrolases, ,and b-glucosidases) It is especially suited for the hydrolysis of the ,hemicellulosic and cellulosic fractions In their specifications they ,come up with 12000 B-glucanase Units/ml. The B-glucanase unit is ,described as the amount of enzyme that releases one micromole of ,reducing function per minute as glucose equivalent, with barley B-glucan ,as substrate (Quoted items are from material they sent me) My advice to you is to be very wary of claims by enzyme manufacturers on units of activity for enzymes (this is a general statement and is not directed toward any single manufacturer, including SAF-ISIS, as I know nothing about this particular company). Enzymes are very ...
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Cell wall hemicelluloses and pectins are O-acetylated at specific positions, but the significance of these substitutions is poorly understood. Using a transgenic approach, we investigated how reducing the extent of O-acetylation in xylan affects cell wall chemistry, plant performance and the recalcitrance of lignocellulose to saccharification. The Aspergillus niger acetyl xylan esterase AnAXE1 was expressed in Arabidopsis under the control of either the constitutively expressed 35S CAMV promoter or a woody-tissue-specific GT43B aspen promoter, and the protein was targeted to the apoplast by its native signal peptide, resulting in elevated acetyl esterase activity in soluble and wall-bound protein extracts and reduced xylan acetylation. No significant alterations in cell wall composition were observed in the transgenic lines, but their xylans were more easily digested by a beta-1,4-endoxylanase, and more readily extracted by hot water, acids or alkali. Enzymatic saccharification of lignocellulose ...
For the production of biofuels and chemicals from plant biomass, a complete utilisation of the cellulose and hemicellulose present is desired. The degradation of these polymers is commonly approached via a physical and/or thermo-assisted chemical pretreatment, followed by enzymatic hydrolysis. In grass-type feedstocks, glucuronoarabinoxylan (GAX) is the major hemicellulose. It is constituted of a β-(1 → 4) linked xylopyranosyl backbone, substituted by side groups, such as O-acetyl groups, arabinofuranosyl residues and 4-O-methyl-α-d-glucopyranosyl uronic acids. The occurrence of substituents in the xylan backbone is highly dependent on the feedstock used. In addition, the abundance and distribution of substituents can be affected by the type and severity of the pretreatment performed [1]. For example, O-acetyl groups and arabinosyl residues are released during hydrothermal pretreatments catalysed by alkali or acids [2-4]. However, glucuronic acid (UA) and its 4-O-methyl etherified derivative ...
α-L-Arabinofuranosidase B25 (Bacteroides ovatus) [ME-ABFBO25] - High purity α-L-arabinofuranosidase (Bacteroides ovatus) for use in research, biochemical enzyme assays and in vitrodiagnostic analysis. EC 3.2.1.55 CAZy Family: GH43 CAS: 9067-74-7 non-reducing end alpha-L-arabinofuranosidase; alpha-L-arabinofuranoside non-reducing end alpha-L-arabinofuranosidase Recombinant. From Bacteroides ovatus. In 50% Glycerol. Specific activity: ~ 25 U/mg protein (on wheat arabinoxylan) at pH 6.5 and 40oC. Stability: | 4 years at -20oC.
The economics for production of secondgeneration (2G) ethanol from sugarcane bagasse in large scale, competing with the cogeneration of electric energy, is still not consolidated. In this scenario, the key for feasibility may be the biorefinery concept, a multiproduct industry using biomass fractions to produce energy, chemicals and by-products. Xylooligosaccharides (XOS) are oligomers of xylose often used as additives in food, animal feeds, and drugs. The effect of NaOH pretreatment on the recovery of xylan for XOS production from sugarcane bagasse under different conditions, namely 121°C, 4-7% NaOH loading, was investigated. The best condition was 4% NaOH and 60 min of reaction, achieving 55% of xylan extraction, without monomer production. In order to produce XOS, soluble and immobilized xylanases were used to hydrolyze commercial birchwood xylan (as control) and the sugarcane bagasse xylan. The immobilized endoxylanase produced XOS with 37% of xylobiose and 20% of xylotriose (w/w). The ...
Busse-Wicher, M., Gomes, T. C. F., Tryfona, T., Nikolovski, N., Stott, K., Grantham, N. J., Bolam, D. N., Skaf, M. S. and Dupree, P. (2014), The pattern of xylan acetylation suggests xylan may interact with cellulose microfibrils as a twofold helical screw in the secondary plant cell wall of Arabidopsis thaliana. The Plant Journal, 79: 492-506. doi: 10.1111/tpj.12575 ...
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Xyloglucan is the major hemicellulosic polymer found in the primary cell walls of dicots. Xyloglucan tethers cellulose microfibrils conferring rigidity and strength for maintenance of cell integrity, and it is thought that its metabolism contributes to cell elongation and thus plant growth. Here, we have cloned and characterized a Eucalyptus grandis gene ortholog of the Arabidopsis thaliana MUR3 gene (xyloglucan galactosyltransferase), thus termed EgMUR3. EgMUR3 represents an intronless sequence of 1,854 bp predicted to encode a protein of 617 amino acid residues. It exhibits 73% identity and 82% similarity to the A. thaliana MUR3 gene. To demonstrate that this gene encodes a functional enzyme, the putative ORF was cloned into a binary vector under the control of a constitutive promoter and transformed into the A. thaliana mur3 mutant. The effect of the genetic complementation was investigated by xyloglucan oligosaccharide fingerprinting of wall material. The results confirmed that EgMUR3 ...
Xylan is the principle component of plant cell wall hemicelluloses. It is a heteroglycan composed of a linear chain of xylopyranose residues bound by β-1,4-linkage, with a variety of constituents linked to the main chain by glycosidic or ester linkages. The biodegradation of xylan requires a set of esterases and glucanases [1, 2]. Among these, acetyl-xylan esterase (AXE, EC 3.1.1.72) hydrolyses acetate group from the chain. Together with xylanases, β-xylosidases, α-arabinofuranosidases and α-methylglucuronidase, the enzyme is an integral part of the xylanolytic system that is capable of the complete hydrolysis of xylan. It releases methyl residue from cell wall, degrades cellulose, and liberates acetic acid from O-acetyl-galactoglucomannan and O-acetyl-4-O-methyl-glucuronoxylan [3]. Microbial AXE production has been preferred to plant or animal sources because of the easier availability, structural stability and ease to genetic manipulation. It has been purified and characterized from ...
Literature References: Large group of polysaccharides found, in association with lignin, in the primary and secondary cell walls of all plants and of some seaweeds. Whether lignin and hemicellulose are chemically bonded or lignin mechanically entraps hemicellulose molecules is still unknown. There are variations in the hemicellulosic composition of plants and even between the organs of the same plant. Hemicellulosic composition of plants changes with growth and maturation and is influenced also by environmental factors during growth. Principal sugar residues present in hemicellulose are: D-xylose, D-glucose, D-galactose, D-mannose, L-arabinose, D-glucuronic acid, D-galacturonic acid, 4-O-methyl-D-glucuronic acid, L-rhamnose and L-fucose. The most ubiquitous and abundant hemicelluloses are the xylans which are composed of linear and/or branched chains of b-(1®4) linked D-xylopyranosyl units. Hemicelluloses from woods: T. E. Timell, Adv. Carbohydr. Chem. 19, 247 (1964); idem, ibid. 20, 409 ...