Modification of the degree of branching of a beta-(1,3)-glucan affects aggregation behavior and activity in an oxidative burst assay

Interaction of beta-glucans with gut microbiota: Dietary origins, structures, degradation, metabolism, and beneficial function

Beta-glucan (BG), a polysaccharide comprised of interfacing glucose monomers joined via beta-glycosidic linkages, can be defined as a type of dietary fiber with high specificity based on its interaction with the gut microbiota. It can induce similar interindividual microbiota responses, thereby having beneficial effects on the human body. In this paper, we review the four main sources of BG (cereals, fungi, algae, and bacteria) and their differences in structure and content. The interaction of BG with gut microbiota and the resulting health effects have been highlighted, including immune enhancement, regulation of serum cholesterol and insulin levels, alleviation of obesity and improvement of cognitive disorders. Finally, the application of BG in food products and its beneficial effects on the gut microbiota of consumers were discussed. Although some of the mechanisms of action remain unclear, revealing the beneficial functions of BG from the perspective of gut microbiota can help provide theoretical support for the development of diets that target the regulation of microbiota.

Reprint of: Advanced glycosidases as ingenious biosynthetic instruments

Until recently, glycosidases, naturally hydrolyzing carbohydrate-active enzymes, have found few synthetic applications in industry, being primarily used for cleaving unwanted carbohydrates. With the establishment of glycosynthase and transglycosidase technology by genetic engineering, the view of glycosidases as industrial biotechnology tools has started to change. Their easy production, affordability, robustness, and substrate versatility, added to the possibility of controlling undesired side hydrolysis by enzyme engineering, have made glycosidases competitive synthetic tools. Current promising applications of engineered glycosidases include the production of well-defined chitooligomers, precious galactooligosaccharides or specialty chemicals such as glycosylated flavonoids. Other synthetic pathways leading to human milk oligosaccharides or remodeled antibodies are on the horizon. This work provides an overview of the synthetic achievements to date for glycosidases, emphasizing the latest trends and outlining possible developments in the field.

β-glucan, "the knight of health sector": critical insights on physiochemical heterogeneities, action mechanisms and health implications

β-glucans, the class of biological response modifier has unceasing attention, not only for its immune stimulating but also for its role as prebiotics, modulator of physiological events etc. and is widely used in the treatment of cancer, diabetes, gastrointestinal disorders, cardiovascular diseases etc. However, β-glucan with different physiochemical properties is found to have discrete clinical functions and thus careful selection of the types of β-glucan plays pivotal role in providing significant and expected clinical outcome. Herein this review, we presented the factors responsible for diverse functional properties of β-glucan, their distinct mode of actions in regulating human health etc. Further, clinical aspects of different β-glucans toward the management of wound care, metabolic dysbiosis, fatty liver disorders and endurance training associated energy metabolism were compiled and exhibited in detail.

Advanced glycosidases as ingenious biosynthetic instruments

Until recently, glycosidases, naturally hydrolyzing carbohydrate-active enzymes, have found few synthetic applications in industry, being primarily used for cleaving unwanted carbohydrates. With the establishment of glycosynthase and transglycosidase technology by genetic engineering, the view of glycosidases as industrial biotechnology tools has started to change. Their easy production, affordability, robustness, and substrate versatility, added to the possibility of controlling undesired side hydrolysis by enzyme engineering, have made glycosidases competitive synthetic tools. Current promising applications of engineered glycosidases include the production of well-defined chitooligomers, precious galactooligosaccharides or specialty chemicals such as glycosylated flavonoids. Other synthetic pathways leading to human milk oligosaccharides or remodeled antibodies are on the horizon. This work provides an overview of the synthetic achievements to date for glycosidases, emphasizing the latest trends and outlining possible developments in the field.

Beta-glucan's varying structure characteristics modulate survival and immune-related genes expression from Vibrio harveyi-infected Artemia franciscana in gnotobiotic conditions

β-Glucans have long been used as an immunostimulant in aquaculture. However, the relationship of its structure to its immunomodulatory properties are poorly understood. In this study, the particle size and chemical structure of β-glucans extracted from wild-type strain of baker's yeast (Saccharomyces cerevisiae) and its null-mutant yeasts Gas1 were characterised. Using Sigma β-glucan as a reference, the immunomodulatory properties of these polysaccharides in the germ-free Artemia franciscana model system in the presence of Vibrio harveyi bacterial challenge were investigated. The survival of the A. franciscana nauplii, upon challenge with V. harveyi, was significantly higher in all three glucan-treated groups compared to the control. The glucan Gas1 with a lower degree of branching and shorter side chain length had the most prominent V. harveyi-protective effects. The particle size did not affect the nauplii survival when challenged with V. harveyi. Results also showed that the salutary effect of the tested glucans was associated with the upregulation of innate immune genes such as lipopolysaccharide and β-1,3-glucan-binding protein (lgbp), high mobility group box protein (hmgb), and prophenoloxidase (proPO). Interestingly, the up-regulation of superoxidase dismutase (sod) and glutathione-s-transferase (gst) was only observed in Gas1 treated group, indicating that Gas1 could function to induce higher reactive oxygen species and stronger immunomodulatory function in A. franciscana, and therefore higher survival rate. The expression of heat shock protein 70 (hsp70), peroxinectin (pxn), and down syndrome cell adhesion molecule (dscam) remain unaltered in response to glucan treatment. Taken together, this study provides insights into the structure-function relationship of β-glucan and the results confirmed that β-glucan can be an effective immunostimulant in aquaculture, especially the Gas1 glucan.

Conformation and cooperative order-disorder transition in aqueous solutions of β-1,3-d-glucan with different degree of branching varied by the Smith degradation

β-1,3-d-glucan with different degrees of branching were obtained by selectively and gradually removing side chains from schizophyllan, a water-soluble triple helical polysaccharide, using the Smith degradation. Size exclusion chromatography combined with a multi-angle light scattering detection was performed in aqueous 0.1 M NaCl. The degree of branching decreased after the Smith degradation, while the molar mass distributions were almost unchanged. The molecular conformation of the Smith-degraded β-1,3-d-glucan was analyzed on the basis of the molar mass dependency of the radius gyration, and found to be comparable to the original triple helix of schizophyllan. Differential scanning calorimetry in deuterium oxide-hexadeuterodimethylsulfoxide mixtures was performed to investigate the effects of the degree of branching on the cooperative order-disorder transition. Removal of side chains affects both the transition temperature and transition enthalpy. The ordered structure is formed by the residual side chains in the triplex unit, so that the linear cooperative system of the triplex is maintained after the Smith degradation.

Catalytic Mechanism of a Novel Glycoside Hydrolase Family 16 "Elongating" β-Transglycosylase

Carbohydrates are complex macromolecules in biological metabolism. Enzymatic synthesis of carbohydrates is recognized as a powerful tool to overcome the problems associated with large scale synthesis of carbohydrates. Novel enzymes with significant transglycosylation ability are still in great demand in glycobiology studies. Here we report a novel glycoside hydrolase family 16 "elongating" β-transglycosylase from Paecilomyces thermophila (PtBgt16A), which efficiently catalyzes the synthesis of higher polymeric oligosaccharides using β-1,3/1,4-oligosaccharides as donor/acceptor substrates. Further structural information reveals that PtBgt16A has a binding pocket around the -1 subsite. The catalytic mechanism of PtBgt16A is partly similar to an exo-glycoside hydrolase, which cleaves the substrate from the non-reducing end one by one. However, PtBgt16A releases the reducing end product and uses the remainder glucosyl as a transglycosylation donor. This catalytic mechanism has similarity with the catalytic mode of amylosucrase, which catalyzes the transglycosylation products gradually extend by one glucose unit. PtBgt16A thus has the potential to be a tool enzyme for the enzymatic synthesis of new β-oligosaccharides and glycoconjugates.