endo-1,4-β-Xylanase (Neocallimastix patriciarum)

endo-1,4-β-Xylanase (EC 3.2.1.8) is employed across a broad range of industries including animal feed, brewing, baking, biofuels, detergents and pulp (paper). Despite its importance, a rapid, reliable, reproducible, automatable assay for this enzyme that is based on the use of a chemically defined substrate has not been described to date. Reported herein is a new enzyme coupled assay procedure, termed the XylX6 assay, that employs a novel substrate, namely 4,6-O-(3-ketobutylidene)-4-nitrophenyl-β-4⁵-O-glucosyl-xylopentaoside. The development of the substrate and associated assay is discussed here and the relationship between the activity values obtained with the XylX6 assay versus traditional reducing sugar assays and its specificity and reproducibility were thoroughly investigated.

A range of α-L-arabinofuranosyl-(1-4)-β-D-xylo-oligosaccharides (AXOS) were produced by hydrolysis of wheat flour arabinoxylan (WAX) and acid debranched arabinoxylan (ADWAX), in the presence and absence of an AXH-d3 α-L-arabinofuranosidase, by several GH10 and GH11 β-xylanases. The structures of the oligosaccharides were characterised by GC-MS and NMR and by hydrolysis by a range of α-L-arabinofuranosidases and β-xylosidase. The AXOS were purified and used to characterise the action patterns of the specific α-L-arabinofuranosidases. These enzymes, in combination with either Cellvibrio mixtus or Neocallimastix patriciarum β -xylanase, were used to produce elevated levels of specific AXOS on hydrolysis of WAX, such as 3²-α-L-Araf-(1-4)-β-D-xylobiose (A³X), 2³-α-L-Araf-(1-4)-β-D-xylotriose (A²XX), 3³-α-L-Araf-(1-4)-β-D-xylotriose (A³XX), 2²-α-L-Araf-(1-4)-β-D-xylotriose (XA²X), 3²-α-L-Araf (1-4)-β-D-xylotriose (XA³X), 2³-α-L-Araf-(1-4)-β-D-xylotetraose (XA²XX), 3³-α-L-Araf-(1-4)-β-D-xylotetraose (XA³XX), 2³ ,3³-di-α-L-Araf-(1-4)-β-D-xylotriose (A²⁺³XX), 2³,3³-di-α-L-Araf-(1-4)-β-D-xylotetraose (XA²⁺³XX), 2⁴,3⁴-di-α-L-Araf-(1-4)-β-D-xylopentaose (XA²⁺³XXX) and 3³,3⁴-di-α-L-Araf-(1-4)-β-D-xylopentaose (XA³A³XX), many of which have not previously been produced in sufficient quantities to allow their use as substrates in further enzymic studies. For A^2,3XX, yields of approximately 16% of the starting material (wheat arabinoxylan) have been achieved. Mixtures of the α-L-arabinofuranosidases, with specific action on AXOS, have been combined with β-xylosidase and β-xylanase to obtain an optimal mixture for hydrolysis of arabinoxylan to L-arabinose and D-xylose.

The most commonly used method for the measurement of the level of endo-xylanase in commercial enzyme preparations is the 3,5-dinitrosalicylic acid (DNS) reducing sugar method with birchwood xylan as substrate. It is well known that with the DNS method, much higher enzyme activity values are obtained than with the Nelson-Somogyi (NS) reducing sugar method. In this paper, we have compared the DNS and NS reducing sugar assays using a range of xylan-type substrates and accurately compared the molar response factors for xylose and a range of xylo-oligosaccharides. Purified beechwood xylan or wheat arabinoxylan is shown to be a suitable replacement for birchwood xylan which is no longer commercially available, and it is clearly demonstrated that the DNS method grossly overestimates endo-xylanase activity. Unlike the DNS assay, the NS assay gave the equivalent colour response with equimolar amounts of xylose, xylobiose, xylotriose and xylotetraose demonstrating that it accurately measures the quantity of glycosidic bonds cleaved by the endo-xylanase. The authors strongly recommend cessation of the use of the DNS assay for measurement of endo-xylanase due to the fact that the values obtained are grossly overestimated due to secondary reactions in colour development.

The knowledge of the molecular properties and arrangements of biopolymers in both solid and solution state are essential in the design of sustainable materials and biomedicine as they are decisive for mechanical strength, flexibility, and biodegradability. However, the structure of most biopolymers at charged interfaces can vary considerably, and their time-dependent visualization in liquid-state still remains challenging. In this work, we employed high-speed atomic force microscopy (HS-AFM) to visualize single xylan macromolecules from alkali-extracted birch and beechwood. On negatively charged mica surfaces, they appeared as individual macromolecules but assembled into aggregates on 3-aminopropyltriethoxysilane (APTES) surfaces (AP-mica). Hence, we further investigated the susceptibility to enzymatic degradation using an endoxylanase, which showed that the individual xylan macromolecules remained intact, while larger assemblies on AP-mica degraded over time. We demonstrate that HS-AFM is a powerful tool for understanding the molecular properties and degradation mechanisms of biopolymers. Moreover, by identifying alignment-dependent binding sites, strategies can be developed to ensure the biodegradability of composite materials by intelligent interface design.

In the present study, the primary by-products of the hemp-seed oil process—hemp seed cake flour and hemp seed protein concentrate-underwent enzymatic hydrolysis using proteases and carbohydrases, either individually or in combination. The effectiveness of these enzymatic treatments in releasing bioactive compounds was evaluated by assessing the antioxidant and anti-inflammatory properties of the aqueous extracts of both hydrolysed and untreated hemp by-products. The aim was to explore their potential senotherapeutic properties and promote their application as dietary supplements. Secondary metabolites such as flavonoids, phenolic acids, and catechins were analysed using high-performance liquid chromatography. Total phenolic, flavonoid, and protein contents were determined using spectrophotometric methods. Scavenging activity (2,2-Diphenyl-1-picrylhydrazyl scavenging assay (DPPH assay)), antioxidant power (Ferric reducing antioxidant power assay (FRAP assay)), and lipid peroxidation-reducing activity (thiobarbituric acid-reactive substance analysis) were assessed through in vitro assays. Possible anti-inflammatory effects were evaluated by assessing haemolysis inhibition. The impact of extracts on albumin glycation induced by exposure to fructose was also determined. To assess the toxicity of extracts, a zebrafish larvae model was employed. All extracts contained significant amounts of phenolic compounds, flavonoids, and proteins, and they exhibited notable activities in reducing lipid peroxidation and stabilising erythrocyte cell membranes. However, they did not significantly influence protein glycation (the glycation inhibition was only in the range of 15–40%). Our research demonstrates the substantial health-promoting potential, including senescence delay, of aqueous extracts from by-products of the hemp-seed oil process, which are available in large quantities and can serve as valuable supplements to support the health of animals, including humans, rather than being discarded as waste from oil production.

The palate fullness (body) and mouthfeel are important sensory attributes influencing the consumers’ beer preference. Among the several parameters affecting these attributes, recent research suggests that the physical characteristics (molar mass and conformation) of starch (dextrins) and non-starch polysaccharides (arabinoxylans and β-glucans) play a critical role. However, the lack of information regarding the physical state of these polysaccharides in beer hinders the sensory evaluation of each component. A method was recently introduced to isolate and solely characterize the molar mass and conformation of beer's starch and non-starch polysaccharides in solution by AF4-MALS-DRI. Therefore, this research evaluated the relationship between the molar mass and conformation of arabinoxylans, β-glucans, and dextrins with the palate fullness and mouthfeel sensorial perception. Additionally, friction, assessed by soft tribology, was analyzed as a triggering mechanism during oral processing. Grains from different sources modified at a low level (steeping degree as parameter) were used to produce bottom-fermented beers with diverse physical characteristics. Regarding the friction response, the variation of correlation behavior at different sliding velocities suggests that the human sensory panel might perceive the palate fullness and mouthfeel at different stages during oral processing. The multivariate analysis suggests that the conformation ratio, from each polysaccharide triggers a distinctive sensory response, being dextrins related to palate fullness while arabinoxylans and β-glucans to mouthfeel. Furthermore, the beer sample substituted with barley modified at a low level presented an increase of branched dextrins in comparison to the (unsubstituted) control, which was related to its increase in palate fullness intensity.

Starch and non‐starch polysaccharides ((N)SPs) are relevant in cereal‐based beverages. Although their molar mass and conformation are important to the sensory characteristics of beer and non‐alcoholic beer, their triggering mechanism in the mouth is not fully understood. Soft tribology has emerged as a tool to mimic oral processing (drinking). The contribution of each (N)SPs to the friction coefficient can be determined when they are enzymatically isolated and characterized by chromatography techniques. Thus, this work aimed to study the relationship between the physical characteristics of isolated (N)SPs and their possible contribution to oral processing through soft tribology (friction). To accomplish this, this research analyzes the effect of grain source (barley, wheat, and oats) and its modification (by steeping degree at two levels) to the (N)SPs´ physical characteristics in wort produced on a laboratory scale. Different characteristics were present in the (N)SPs due to the grain source and the degree of modification. When comparing the impact of the grain source, the malted oats showed the highest molar masses. A higher modification degree produced smaller and more compact structures except for wheat's arabinoxylans and dextrins. The conformation ratio (rrms/rhyd) values indicate the existence of sphere and micro‐gel structures within each (N)SPs, with branches in arabinoxylans and dextrins. Subsequently, soft tribology was measured on all the worts and their correlation to the (N)SPs' data was performed by multivariate analysis. The wort produced with high modification grains generated higher friction responses. However, this was only statistically significant in barley samples. The multivariate analysis showed that within the mouth (tongue) velocity, the apparent density of the (N)SPs, and the molar mass of arabinoxylans and β‐glucans may influence the friction response and, hence, the oral processing in the mouth during oral processing (drinking).

Synthetic glycans (SGs) containing glycosidic linkages and structures not identified in nature offer a means for deliberately altering microbial community properties. Here pools of SG oligosaccharides were generated via polymerization of monosaccharides and screened for their ability to increase saccharolytic Bacteroides in ex vivo cultures of human fecal samples. A lead SG preparation was orally administered to gnotobiotic mice harboring a consortium of 56 cultured, phylogenetically diverse human gut bacteria and fed a Western diet. The abundances of 3 of 15 Bacteroides strains increased, most prominently B. intestinalis. Underlying mechanisms were characterized by analyzing in vivo expression of the carbohydrate utilization machinery, using retrievable microscopic paramagnetic particles with bound SG oligosaccharides and assaying SG degradation by individual purified B. intestinalis glycoside hydrolases. The results reveal that SGs can selectively co-opt carbohydrate utilization machinery in different human gut Bacteroides and demonstrate a means for identifying artificial carbohydrate structures for targeted bacterial manipulation.

Xylans' unique properties make it attractive for a variety of industries, including paper, food, and biochemical production. While for some applications the preservation of its natural structure is crucial, for others the degradation into monosaccharides is essential. For the complete breakdown, the use of several enzymes is required, due to its structural complexity. In fact, the specificity of enzymatically-catalyzed reactions is guided by the surface, limiting or regulating accessibility and serving structurally encoded input guiding the actions of the enzymes. Here, we investigate enzymes at surfaces rich in xylan using surface plasmon resonance spectroscopy. The influence of diffusion and changes in substrate morphology is studied via enzyme surface kinetics simulations, yielding reaction rates and constants. We propose kinetic models, which can be applied to the degradation of multilayer biopolymer films. The most advanced model was verified by its successful application to the degradation of a thin film of polyhydroxybutyrate treated with a polyhydroxybutyrate-depolymerase. The herein derived models can be employed to quantify the degradation kinetics of various enzymes on biopolymers in heterogeneous environments, often prevalent in industrial processes. The identification of key factors influencing reaction rates such as inhibition will contribute to the quantification of intricate dynamics in complex systems.

Despite the potential of lignocellulose in manufacturing value-added chemicals and biofuels, its efficient biotechnological conversion by enzymatic hydrolysis still poses major challenges. The complex interplay between xylan, cellulose, and lignin in fibrous materials makes it difficult to assess underlying physico- and biochemical mechanisms. Here, we reduce the complexity of the system by creating matrices of cellulose, xylan, and lignin, which consists of a cellulose base layer and xylan/lignin domains. We follow enzymatic degradation using an endoxylanase by high-speed atomic force microscopy and surface plasmon resonance spectroscopy to obtain morphological and kinetic data. Fastest reaction kinetics were observed at low lignin contents, which were related to the different swelling capacities of xylan. We demonstrate that the complex processes taking place at the interfaces of lignin and xylan in the presence of enzymes can be monitored in real time, providing a future platform for observing phenomena relevant to fiber-based systems.