Advance diversity of enzymatically modified arabinoxylan from wheat chaff

Effect of glycoside hydrolase-mediated wheat arabinoxylan hydrolysate on gut microbiota and metabolite profiles

Cereal arabinoxylans (AX) are complex non-digestible polysaccharides and their molecular structural features significantly influence their degradation and metabolic behaviors within the body. This study focuses on investigating the impact of wheat AX hydrolysates produced by different glycoside hydrolases on the gut microbiota during colonic fermentation. Endo-1,4-β-xylanase (XYN) and arabinofuranosidase (ARF) were used to hydrolyze the xylan backbone and remove the arabinose side chains, respectively. The digestive and degradation fate was analyzed through in vitro simulated gastrointestinal digestion and colonic fermentation models. Results indicated that all hydrolase-treated groups exhibited different intestinal flora community structures, characterized by enhanced diversity and reduced richness of gut microbiota, along with differentially enriched bacterial taxa compared to native AX. The glycosidase-treated group showed greater advantages in promoting the growth of beneficial bacteria such as Bacteroides, Ruminococcus, and Faecalibacterium and produced higher levels of beneficial metabolites, mainly acetate, butyrate and caproate. Lower degrees of polymerization and side-chain substitution in AX enzymatic hydrolysate, along with higher levels of arabinoxylan-oligosaccharides (AXOS) exhibited the optimal promotion effects. However, certain gut bacteria such as Prevotella and Bifidobacterium prefer structurally intact long-chain AX. This study demonstrates that AX hydrolysates with different molecular characteristics, induced by specific hydrolases selectively influence distinct microbial consortia. Higher levels of short-chain unsubstituted XOS are more effective at promoting intestinal health and maintaining intestinal homeostasis.

Molecular and technical aspects on the interaction of bovine serum albumin with pyrazine derivatives: From molecular docking to spectroscopy study

In order to better understand the transport and action mechanism of flavor substance and proteins in human body, the interaction mechanism between pyrazine derivatives and bovine serum albumin (BSA) was studied by molecular dynamics simulation and a series of spectroscopic methods. In molecular docking, it was observed that the small molecules were surrounded by hydrophobic amino acid residues of the protein, and the main amino acid residues formed π-π interaction and hydrogen bond interaction with BSA. The results of fluorescence emission spectroscopy combined with thermodynamic analysis showed that static quenching was the main mechanism of the interaction between three pyrazine derivatives and BSA, which was dominated by hydrophobic interaction. Synchronous fluorescence spectroscopy and three-dimensional fluorescence spectroscopy combined with molecular dynamics simulation proved that the pyrazine derivatives changed the conformation of BSA. In summary, pyrazine derivatives can interact with BSA, and the complexation of the complex changes its spatial conformation. The research in this paper has positive significance for understanding the binding, transport, and metabolism of pyrazine compounds in the process of blood circulation and provides key data for the metabolism of pyrazine compounds in vivo. PRACTICAL APPLICATION: The interaction of pyrazine derivatives-BSA is studied by multi-spectra and MD. The fluorescence quenching of pyrazine derivatives-BSA is static quenching. The main force between pyrazine derivatives and BSA is hydrophobic force. There is only one site of association between pyrazine derivatives and BSA. Pyrazine derivatives have effects on conformation of BSA.

In vivo mechanism of the interaction between trimethylamine lyase expression and glycolytic pathways

Recent studies confirmed that host-gut microbiota interactions modulate disease-linked metabolite TMA production via TMA lyase. However, microbial enzyme production mechanisms remain unclear. In the present study, we investigated the impact of dietary and intervention factors on gut microbiota, microbial gene expression, and the interplay between TMA lyase and glycolytic pathways in mice. Using 16S rRNA gene sequencing, metagenomics, and metabolomics, the gut microbiota composition and microbial functional gene expression profiles related to TMA lyase and glycolytic enzymes were determined. The results revealed that distinct diets and intervention factors altered gut microbiota, gene expression, and metabolites linked to glycine metabolism and glycolysis. Notably, an arabinoxylan-rich diet suppressed genes linked to choline, glycine, glycolysis, and TMA lyase, favoring glycine utilization via pyruvate pathways. Glycolytic inhibitors amplified these effects, mainly inhibiting pyruvate kinase. Our findings underscored the crosstalk between TMA lyase and glycolytic pathways, regulating glycine levels, and suggested avenues for targeted interventions and personalized diets to curb choline TMA lyase production.

Synthesis and antitumor activity of bagasse xylan derivatives modified by graft-esterification and cross-linking

A crucial aspect in achieving sustainable development of biomass materials is the modification of renewable polysaccharides to create various high-value functional materials. In this paper, bagasse xylan (BX) was used as a raw material to introduce benzyl methacrylate (BMA) through graft copolymerization reaction to generate the intermediate product BX-g-BMA. Subsequently, the target product (CA-BX-g-BMA) was synthesized by catalytic esterification of BX-g-BMA with citric acid (CA) in AmimCl ionic liquid. Meanwhile, the characterization and bioactivity studies of CA-BX-g-BMA were carried out. The graft copolymerization and esterification reactions induced significant changes in the morphological structure of BX and obviously improved its thermal stability and crystallinity. The application of density functional theory (DFT), molecular electrostatic potential (MEP) and molecular docking has revealed that CA-BX-g-BMA possesses multiple active sites, strong biological activity and a strong binding affinity to 6RCF tumor protein with a binding energy of -32.26 kJ/mol. The in vitro antitumor activity of this novel derivative was tested by MTT assay, and the results showed that CA-BX-g-BMA was non-toxic to normal cells and inhibited MDA-MB-231 (breast cancer cells) by up to 32.16 % ± 4.89 %, which is approximately 11 times higher than that of BX. The exploration of these properties is essential to promote future multidisciplinary applications of BX derivatives.

Highly efficient synergistic activity of an α-L-arabinofuranosidase for degradation of arabinoxylan in barley/wheat

Here, an α-L-arabinofuranosidase (termed TtAbf62) from Thermothelomyces thermophilus is described, which efficiently removes arabinofuranosyl side chains and facilitates arabinoxylan digestion. The specific activity of TtAbf62 (179.07 U/mg) toward wheat arabinoxylan was the highest among all characterized glycoside hydrolase family 62 enzymes. TtAbf62 in combination with endoxylanase and β-xylosidase strongly promoted hydrolysis of barley and wheat. The release of reducing sugars was significantly higher for the three-enzyme combination relative to the sum of single-enzyme treatments: 85.71% for barley hydrolysis and 33.33% for wheat hydrolysis. HPLC analysis showed that TtAbf62 acted selectively on monosubstituted (C-2 or C-3) xylopyranosyl residues rather than double-substituted residues. Site-directed mutagenesis and interactional analyses of enzyme-substrate binding structures revealed the catalytic sites of TtAbf62 formed different polysaccharide-catalytic binding modes with arabinoxylo-oligosaccharides. Our findings demonstrate a "multienzyme cocktail" formed by TtAbf62 with other hydrolases strongly improves the efficiency of hemicellulose conversion and increases biomass hydrolysis through synergistic interaction.

Characterization of feruloyl esterases from Pecoramyces sp. F1 and the synergistic effect in biomass degradation

Feruloyl esterase (FAE; EC 3.1.1.73) cleaves the ester bond between ferulic acid (FA) and sugar, to assist the release of FAs and degradation of plant cell walls. In this study, two FAEs (Fae13961 and Fae16537) from the anaerobic fungus Pecoramyces sp. F1 were heterologously expressed in Pichia pastoris (P. pastoris). Compared with Fae16537, Fae13961 had higher catalytic efficiency. The optimum temperature and pH of both the FAEs were 45 ℃ and 7.0, respectively. They showed good stability-Fae16537 retained up to 80% activity after incubation at 37 ℃ for 24 h. The FAEs activity was enhanced by Ca²⁺ and reduced by Zn²⁺, Mn²⁺, Fe²⁺ and Fe³⁺. Additionally, the effect of FAEs on the hydrolytic efficiency of xylanase and cellulase was also determined. The FAE Fae13961 had synergistic effect with xylanase and it promoted the degradation of xylan substrates by xylanase, but it did not affect the degradation of cellulose substrates by cellulase. When Fae13961 was added in a mixture of xylanase and cellulase to degrade complex agricultural biomass, it significantly enhanced the mixture's ability to disintegrate complex substrates. These FAEs could serve as superior auxiliary enzymes for other lignocellulosic enzymes in the process of degradation of agricultural residues for industrial applications.

Fabrication and stabilization mechanisms of Pickering emulsions based on gliadin/arabinoxylan complexes

In the present work, the Pickering emulsions with enhanced oxidation stability were fabricated using gliadin (G)/arabinoxylan nanoparticles (GANPs). The influence of different G/AX ratios on the properties of GANPs and corresponding physicochemical characteristics of Pickering emulsions were investigated. Results indicated that the droplet size and ζ-potential of Pickering emulsions declined with the decrease of G/AX ratios. Pickering emulsion with the smallest G/AX ratio (1:4) exhibited excellent oxidative and coalescence stability due to the formation of viscoelastic gel network, which was supported by confocal laser scanning microscopy (CLSM) images. Furthermore, the increase of salt ions in a lower concentration (0-0.2 M) was conducive to the flocculation of the droplets, while further increasing the NaCl concentration impaired the emulsion stability. Such elements revealed that G/AX complex is a promising stabilizer of Pickering emulsions with prominent antioxidant activity, which have favorable potential applications in protecting the functional properties of polyunsaturated fatty acids (PUFAs).

Arabinoxylans as Functional Food Ingredients: A Review

The health benefits of fibre consumption are sound, but a more compressive understanding of the individual effects of different fibres is still needed. Arabinoxylan is a complex fibre that provides a wide range of health benefits strongly regulated by its chemical structure. Arabinoxylans can be found in various grains, such as wheat, barley, or corn. This review addresses the influence of the source of origin and extraction process on arabinoxylan structure. The health benefits related to short-chain fatty acid production, microbiota regulation, antioxidant capacity, and blood glucose response control are discussed and correlated to the arabinoxylan's structure. However, most studies do not investigate the effect of AX as a pure ingredient on food systems, but as fibres containing AXs (such as bran). Therefore, AX's benefit for human health deserves further investigation. The relationship between arabinoxylan structure and its physicochemical influence on cereal products (pasta, cookies, cakes, bread, and beer) is also discussed. A strong correlation between arabinoxylan's structural properties (degree of branching, solubility, and molecular mass) and its functionalities in food systems can be observed. There is a need for further studies that address the health implications behind the consumption of arabinoxylan-rich products. Indeed, the food matrix may influence the effects of arabinoxylans in the gastrointestinal tract and determine which specific arabinoxylans can be included in cereal and non-cereal-based food products without being detrimental for product quality.

Enzymatic upgrading of heteroxylans for added-value chemicals and polymers

Xylan is one of the most abundant, natural polysaccharides, and much recent interest focuses on upgrading heteroxylan to make use of its unique structures and chemistries. Significant progress has been made in the discovery and application of novel enzymes for debranching and modifying heteroxylans. Debranching enzymes include acetylxylan esterases, α-l-arabinofuranosidases and α-dglucuronidases that release side groups from the xylan backbone to recover both biochemicals and less substituted xylans for polymer applications in food packaging or drug delivery systems. Besides esterases and hydrolases, many oxidoreductases including carbohydrate oxidases, lytic polysaccharide monooxygenases, laccases and peroxidases have been also applied to alter different types of xylans for improved physical and chemical properties. This review will highlight the recent discovery and application of enzymes for upgrading xylans for use as added-value chemicals and in functional polymers.

Characterization of Feruloyl Esterase from Bacillus pumilus SK52.001 and Its Application in Ferulic Acid Production from De-Starched Wheat Bran

Feruloyl esterase (FAE; EC 3.1.1.73) catalyzes the hydrolysis of the 4-hydroxy-3-methoxycinnamoyl group in an esterified sugar to assist in waste biomass degradation or to release ferulic acid (FA). An FAE-producing strain was isolated from humus soil samples and identified as Bacillus pumilus SK52.001. The BpFAE gene from B. pumilus SK52.001 was speculated and heterogeneously expressed in Bacillus subtilis WB800 for the first time. The enzyme exists as a monomer with 303 amino acids and a molecular mass of 33.6 kDa. Its specific activity was 377.9 ± 10.3 U/ (mg protein), using methyl ferulate as a substrate. It displays an optimal alkaline pH of 9.0, an optimal temperature of 50 °C, and half-lives of 1434, 327, 235, and 68 min at 50, 55, 60, and 65 °C, respectively. Moreover, the purified BpFAE released 4.98% FA of the alkali-acidic extractable FA from de-starched wheat bran (DSWB). When the DSWB was enzymatically degraded by the synergistic effect of the BpFAE and commercial xylanase, the FA amount reached 49.47%. It suggested that the alkaline BpFAE from B. pumilus SK52.001, which was heterologously expressed in B. subtilis WB800, possesses great potential for biomass degradation and achieving high-added value FA production from food by-products.

Molecular modification, structural characterization, and biological activity of xylans

The differences in the source and structure of xylans make them have various biological activities. However, due to their inherent structural limitations, the various biological activities of xylans are far lower than those of commercial drugs. Currently, several types of molecular modification methods have been developed to address these limitations, and many derivatives with specific biological activity have been obtained. Further research on structural characteristics, structure-activity relationship and mechanism of action is of great significance for the development of xylan derivatives. Therefore, the major molecular modification methods of xylans are introduced in this paper, and the primary structure and conformation characteristics of xylans and their derivatives are summarized. In addition, the biological activity and structure-activity relationship of the modified xylans are also discussed.