Glucan Structure Research Articles

Detailed structural characterization of five water-insoluble α-glucans produced by glucansucrases from Streptococcus spp.

Water-insoluble α-glucans synthesized from sucrose by glucansucrases from Streptococcus spp. are essential in dental plaque and caries formation. Because limited information is available on the fine structure of these biopolymers, we analyzed the structures of unmodified glucans produced by five recombinant Streptococcus (S.) mutans DSM 20523 and S. salivarius DSM 20560 glucansucrases in detail. A combination of methylation analysis, endo-dextranase and endo-mutanase hydrolyses, and HPSEC-RI was used. Furthermore, crystal-like regions were analyzed by using XRD and 13C MAS NMR spectroscopy. Our results showed that the glucan structures were highly diverse: Two glucans with 1,3- and 1,6-linkages were characterized in detail besides an almost exclusively 1,3-linked and a linear 1,6-linked glucan. Furthermore, one glucan contained 1,3-, 1,4-, and 1,6-linkages and thus had an unusual, not yet described structure. It was demonstrated that the glucans had a varying structural architecture by using partial enzymatic hydrolyses. Furthermore, crystal-like regions formed by 1,3-glucopyranose units were observed for the two 1,3- and 1,6-linked glucans and the linear 1,3-linked glucan. 1,6-linked regions were mobile and not involved in the crystal-like areas. Altogether, our results broaden the knowledge of the structure of water-insoluble α-glucans from Streptococcus spp.

Structure, Physicochemical Properties and Biological Activity of Lipopolysaccharide from the Rhizospheric Bacterium Ochrobactrum quorumnocens T1Kr02, Containing d-Fucose Residues.

Lipopolysaccharides (LPSs) are major components of the outer membranes of Gram-negative bacteria. In this work, the structure of the O-polysaccharide of Ochrobactrum quorumnocens T1Kr02 was identified by nuclear magnetic resonance (NMR), and the physical-chemical properties and biological activity of LPS were also investigated. The NMR analysis showed that the O-polysaccharide has the following structure: →2)-β-d-Fucf-(1→3)-β-d-Fucp-(1→. The structure of the periplasmic glucan coextracted with LPS was established by NMR spectroscopy and chemical methods: →2)-β-d-Glcp-(1→. Non-stoichiometric modifications were identified in both polysaccharides: 50% of d-fucofuranose residues at position 3 were O-acetylated, and 15% of d-Glcp residues at position 6 were linked with succinate. This is the first report of a polysaccharide containing both d-fucopyranose and d-fucofuranose residues. The fatty acid analysis of the LPS showed the prevalence of 3-hydroxytetradecanoic, hexadecenoic, octadecenoic, lactobacillic, and 27-hydroxyoctacosanoic acids. The dynamic light scattering demonstrated that LPS (in an aqueous solution) formed supramolecular particles with a size of 72.2 nm and a zeta-potential of -21.5 mV. The LPS solution (10 mkg/mL) promoted the growth of potato microplants under in vitro conditions. Thus, LPS of O. quorumnocens T1Kr02 can be recommended as a promoter for plants and as a source of biotechnological production of d-fucose.

Pullulan Production Utilizing Various Carbon Sources by Aureobasidium melanogenum DSM 2404 as Biotherapeutic Tool in Biomedical Applications

Introduction: Pullulan is a biodegradable biopolymer made up of maltotriose subunits that are water-soluble. It has a direct glucan structure comprising α-1,4 and α-1,6 linkages in a 2:1 ratio, which gives it exceptional physical and structural properties, making it a suitable choice for application in biomedical applications. Despite its potential benefits, the price of production is expansive, and productivity is low, which are significant drawbacks. Therefore, the objective of this work is to identify the ideal carbon source for Aureobasidium melanogenum DSM 2404 to produce high pullulans. Methods: In shake flask studies, the effects of different carbon sources, such as maltose, glucose, sucrose, lactose, and xylose, on cell growth and pullulan generation by Aureobasidium melanogenum DSM 2404 were examined. Results: The highest pullulan production was obtained from sucrose (13.38 g L-1) compared to other types of carbon sources used in the fermentation medium. The maximal pullulan production rate of 0.112 [g-1 L-1 h-1] was obtained in sucrose culture. This suggests that sucrose provides favorable conditions for the microorganisms to produce pullulan at a faster rate compared to other sugars. Conclusion: Sucrose was found to be the most efficient carbon source for the synthesis of pullulan using Aureobasidium melanogenum DSM 2404 generating 13.38 g L-1 of pullulan.

Dectin-1 multimerization and signaling depends on fungal β-glucan structure and exposure

Dectin-1A is a C-type lectin innate immunoreceptor that recognizes β-(1,3;1,6)-glucan, a structural component of Candida species cell walls. β-Glucans can adopt solution structures ranging from random coil to insoluble fiber due to tertiary (helical) and quaternary structure. Fungal β-glucans of medium and high molecular weight are highly structured, but low molecular weight glucan is much less structured. Despite similar affinity for Dectin-1, the ability of glucans to induce Dectin-1A-mediated signaling correlates with degree of structure. Glucan denaturation experiments showed that glucan structure determines agonistic potential, but not receptor binding affinity. We explored the impact of glucan structure on molecular aggregation of Dectin-1A. Stimulation with glucan signaling decreased Dectin-1A diffusion coefficient. Fluorescence measurements provided direct evidence of ligation-induced Dectin-1A aggregation, which positively correlated with increasing glucan structure content. In contrast, Dectin-1A is predominantly in a low aggregation state in resting cells. Molecular aggregates formed during interaction with highly structured, agonistic glucans did not exceed relatively small (<15 nm) clusters of a few engaged receptors. Finally, we observed increased molecular aggregation of Dectin-1A at fungal particle contact sites in a manner that positively correlated with the degree of exposed glucan on the particle surface. These results indicate that Dectin-1A senses the solution conformation of β-glucans through their varying ability to drive receptor dimer/oligomer formation and activation of membrane proximal signaling events.

Olive Oil as a Transport Medium for Bioactive Molecules of Plants?-An In Situ Study.

(1) Caries and erosions still remain a challenge for preventive dentistry. Certain plant extracts have shown beneficial effects in preventive dentistry. The aim of this study was to evaluate the antibacterial, anti-adherent and erosion-protective properties of ellagic acid (EA) as a polyphenolic agent. The combination with olive oil was investigated additionally to verify a possible improved bioactive effect of EA. (2) An in situ study was carried out with six subjects. Individual splints were prepared with bovine enamel specimens. The splints were worn for 1 min (pellicle formation time). Thereafter, 10 min rinses were performed with EA in water/in oil. Bacterial adherence was evaluated by fluorescence microscopy (DAPI, ConA, BacLight) after an 8 h oral exposition time. Additionally, the splints were worn for 30 min to quantify demineralization processes. The ultrastructure of the pellicle was investigated after an oral exposure time of 2 h under a transmission electron microscope. Statistical analysis was performed by Kruskal-Wallis tests, Mann-Whitney U tests and Bonferroni-Holm correction. (3) Rinsing with EA led to a significant reduction of adherent vital and dead bacteria. The combination with olive oil did not improve these outcomes. The assessment of glucan structures after rinsing with EA in water showed significant effects. Significant differences were observed for both rinses in calcium release at pH 3.0. After rinsing with EA in oil, significantly less calcium was released compared to rinsing with EA in water (pH = 3.0). (4) Olive oil is not suitable as a transport medium for lipophilic polyphenols. EA has anti-adherent and antibacterial properties in situ. EA also shows erosion-protective effects, which can be enhanced in combination with olive oil depending on the pH value. Ellagic acid has a neutral pH and could be an opportunity in the treatment of specific patient groups (xerostomia or mucositis).

In Situ Raman Analysis of Biofilm Exopolysaccharides Formed in Streptococcus mutans and Streptococcus sanguinis Commensal Cultures.

This study probed in vitro the mechanisms of competition/coexistence between Streptococcus sanguinis (known for being correlated with health in the oral cavity) and Streptococcus mutans (responsible for aciduric oral environment and formation of caries) by means of quantitative Raman spectroscopy and imaging. In situ Raman assessments of live bacterial culture/coculture focusing on biofilm exopolysaccharides supported the hypothesis that both species engaged in antagonistic interactions. Experiments of simultaneous colonization always resulted in coexistence, but they also revealed fundamental alterations of the biofilm with respect to their water-insoluble glucan structure. Raman spectra (collected at fixed time but different bacterial ratios) showed clear changes in chemical bonds in glucans, which pointed to an action by Streptococcus sanguinis to discontinue the impermeability of the biofilm constructed by Streptococcus mutans. The concurrent effects of glycosidic bond cleavage in water-insoluble α - 1,3-glucan and oxidation at various sites in glucans' molecular chains supported the hypothesis that secretion of oxygen radicals was the main "chemical weapon" used by Streptococcus sanguinis in coculture.

Characterization of Dextran Biosynthesized by Glucansucrase from Leuconostoc pseudomesenteroides and Their Potential Biotechnological Applications

Glucansucrase was purified from Leuconostoc pseudomesenteroides. The glucansucrase exhibited maximum activity at pH 5.5 and 30 °C. Ca2+ significantly promoted enzyme activity. An exopolysaccharide (EPS) was synthesized by this glucansucrase in vitro and purified. The molecular weight of the EPS was 3.083 × 106 Da. Fourier transform infrared (FT-IR) and nuclear magnetic resonance (NMR) spectroscopy showed that the main structure of glucan was 97.3% α-(1→6)-linked D-glucopyranose units, and α-(1→3) branched chain accounted for 2.7%. Scanning electron microscopy (SEM) observation of dextran showed that its surface was smooth and flaky. Atomic force microscopy (AFM) of dextran revealed a chain-like microstructure with many irregular protuberances in aqueous solution. The results showed that dextran had good thermal stability, water holding capacity, water solubility and emulsifying ability (EA), as well as good antioxidant activity; thus it has broad prospects for development in the fields of food, biomedicine, and medicine.

Interactions between structure and function of resistant glucans for alleviating type 2 diabetes mellitus (T2DM) and its complications in mice

Resistant glucan, a functional dietary fiber, has been shown to alleviate type 2 diabetes mellitus (T2DM) and its complications in clinical studies. However, the interactions between the special structure of resistant glucan and the metabolism-related pathways in T2DM have not yet been systematically studied. This study identified the structural differences between resistant glucans prepared by new and old methods. Oral gavage with two resistant glucans in T2DM mice, led to significant improvements in glucose and lipid metabolism as measured by related indicators (including gut microbiota, fecal metabolites, and physiological and biochemical indexes). According to these results, in addition to van der Waals forces, micelle formation, and hydrogen bonding, the branching structures of resistant glucans produced more hydroxyl, carbonyl, and keto groups that linked cholesterols, cholesterol esters, and low-density lipoprotein intermediates. Moreover, after lipid clearing, the metabolic environment was more conducive to the proliferation of specific gut microbiota (including Phascolarctobacterium, Prevotella, Butyricicoccus, Weissella, and Anaerostipes) with decreasing abundance ratios of Firmicutes and Bacteroides. This facilitated the synthesis of high-density lipoprotein, conversion of cholesterol into coprostanol, and production of short-chain fatty acids and bile acids. Our findings provide a foundation for comprehensive investigation of the structure of resistant glucan in the promotion and prevention of T2DM.

Natural polysaccharides from Glycyrrhiza uralensis residues with typical glucan structure showing inhibition on α-glucosidase activities

Two neutral Glycyrrhiza polysaccharide (GP), named GP-LA and GP-HA, with molecular weights of 3.023 × 105 and 1.291 × 105, respectively, were extracted from Glycyrrhiza residues by hot acid extraction (HA) and low-temperature acid extraction (LA) and purified by column chromatography. Comprehensive analysis showed that the backbone of GP was composed of →4)-β-D-Glcp-(1→. For GP-LA, the side chain probably composed of β-L-Araf-(1→, →5)-β-L-Araf-(1→, →4)-β-D-Xylp-(1→, β-D-Glcp-(1→, →3,4)-α-D-Glcp-(1→, →4,6)-α- D-Glcp-(1→, and for GP-LA, the side chain probably composed of→6)-β-D-Galp-(1→, -α-D-Glcp-(1→, →3,4)-α-D-Glcp-(1→, →2,4)-α-D-Glcp-(1→, →4,6)- D-Glcp-(1→. The GP had a triple helix conformation and numerous irregular spherical particles with smooth surfaces. Atomic force microscopy (AFM) confirmed that GP-HA possessed single-branched structures and GP-LA possessed cross-linked network structures. X-ray diffraction (XRD) analysis revealed that GP-LA had both crystalline and amorphous structures, but GP-HA had no crystal structure. Furthermore, the results indicated that GP-LA and GP-HA exhibited certain inhibition activity on α-glucosidase. CD spectra and fluorescence intensity measurements confirmed that the secondary structure of α-glucosidase changed with the addition of GP.

Raman Metabolomics of Candida auris Clades: Profiling and Barcode Identification.

This study targets on-site/real-time taxonomic identification and metabolic profiling of seven different Candida auris clades/subclades by means of Raman spectroscopy and imaging. Representative Raman spectra from different Candida auris samples were systematically deconvoluted by means of a customized machine-learning algorithm linked to a Raman database in order to decode structural differences at the molecular scale. Raman analyses of metabolites revealed clear differences in cell walls and membrane structure among clades/subclades. Such differences are key in maintaining the integrity and physical strength of the cell walls in the dynamic response to external stress and drugs. It was found that Candida cells use the glucan structure of the extracellular matrix, the degree of α-chitin crystallinity, and the concentration of hydrogen bonds between its antiparallel chains to tailor cell walls’ flexibility. Besides being an effective ploy in survivorship by providing stiff shields in the α–1,3–glucan polymorph, the α–1,3–glycosidic linkages are also water-insoluble, thus forming a rigid and hydrophobic scaffold surrounded by a matrix of pliable and hydrated β–glucans. Raman analysis revealed a variety of strategies by different clades to balance stiffness, hydrophobicity, and impermeability in their cell walls. The selected strategies lead to differences in resistance toward specific environmental stresses of cationic/osmotic, oxidative, and nitrosative origins. A statistical validation based on principal component analysis was found only partially capable of distinguishing among Raman spectra of clades and subclades. Raman barcoding based on an algorithm converting spectrally deconvoluted Raman sub-bands into barcodes allowed for circumventing any speciation deficiency. Empowered by barcoding bioinformatics, Raman analyses, which are fast and require no sample preparation, allow on-site speciation and real-time selection of appropriate treatments.

Tuning heterologous glucan biosynthesis in yeast to understand and exploit plant starch diversity

BackgroundStarch, a vital plant-derived polysaccharide comprised of branched glucans, is essential in nutrition and many industrial applications. Starch is often modified post-extraction to alter its structure and enhance its functionality. Targeted metabolic engineering of crops to produce valuable and versatile starches requires knowledge of the relationships between starch biosynthesis, structure, and properties, but systematic studies to obtain this knowledge are difficult to conduct in plants. Here we used Saccharomyces cerevisiae as a testbed to dissect the functions of plant starch biosynthetic enzymes and create diverse starch-like polymers.ResultsWe explored yeast promoters and terminators to tune the expression levels of the starch-biosynthesis machinery from Arabidopsis thaliana. We systematically modulated the expression of each starch synthase (SS) together with a branching enzyme (BE) in yeast. Protein quantification by parallel reaction monitoring (targeted proteomics) revealed unexpected effects of glucan biosynthesis on protein abundances but showed that the anticipated broad range of SS/BE enzyme ratios was maintained during the biosynthetic process. The different SS/BE ratios clearly influenced glucan structure and solubility: The higher the SS/BE ratio, the longer the glucan chains and the more glucans were partitioned into the insoluble fraction. This effect was irrespective of the SS isoform, demonstrating that the elongation/branching ratio controls glucan properties separate from enzyme specificity.ConclusionsOur results provide a quantitative framework for the in silico design of improved starch biosynthetic processes in plants. Our study also exemplifies a workflow for the rational tuning of a complex pathway in yeast, starting from the selection and evaluation of expression modules to multi-gene assembly and targeted protein monitoring during the biosynthetic process.

In vitro elucidation of antioxidant, antiproliferative, and apoptotic potential of yeast-derived β-1,3-glucan particles against cervical cancer cells.

Cancer is the leading cause of mortality worldwide and in particular is the fourth most common cause of mortality in women every year. Conventional treatments for cancer are chemotherapy and radiation therapy, which have various kinds of side effects. Hence, there is a high need to develop alternative, efficient, and safer therapies for cancer treatment. β-Glucan, a novel polysaccharide isolated from baker's yeast Saccharomyces cerevisiae, shows noteworthy cytotoxicity toward a variety of cancer cell lines in vitro. In this research, we characterized the β-glucan with high-performance thin-layer chromatography (HPTLC) analysis and found that d-glucose units with β-1,3 links are the major component of the extracted β-glucan particles. Fourier transform IR (FTIR) analysis confirmed a β-(1→3)-linked glucan structure. In vitro cell cytotoxicity was evaluated by MTT with IC50 136 μg/ml, and therapeutic potential was assessed by various assays using values below and above the IC50. A significant reactive oxygen species (ROS) generation at 50-150 μg/ml of concentrations indicated the apoptosis of cervical cancer cells. Along with ROS generation, these concentrations were also found to induce morphological changes such as fragmentation in DNA upon staining HeLa cells with DAPI. Mitochondrial membrane potential was significantly reduced after increasing the dose of treatment, assessed with the help of MitoTracker dye. Hence, by all these experimental supports, we observed that β-glucan has the potential to slow down the growth of cervical cancer cells, and it can be further investigated for unfolding its complete anticancer potential.

Structural characterization of a soluble polysaccharide SSPS1 from soy whey and its immunoregulatory activity in macrophages

A soluble soybean polysaccharide SSPS1 with a molecular weight of 2737 kDa was extracted and purified from soy whey. SSPS1 was composed of glucose (97.3 %) and a small amount of mannose (2.7 %). Structural analysis results suggested that SSPS1 had a → 6)-α-d-Glcp-(1 → glucan structure, with a trace amount of α-d-Glcp-(1 → connected to the main chain via O-3. In vitro immunological experiments suggested that SSPS1 enhanced the growth rate and phagocytic activity of RAW 264.7 macrophages. In addition, SSPS1 stimulated the secretion of cytokines (TNF-α, INF-β, IL-6 and IL-1β) as well as nitric oxide (NO) production through upregulating the expression of the related genes and proteins in RAW 264.7 cells. This study provided a new method for efficient utilization of soy whey, and the results indicate that SSPS1 extracted from soy whey could be used as a novel immunomodulator.

LIKE EARLY STARVATION 1 alters the glucan structures at the starch granule surface and thereby influences the action of both starch-synthesizing and starch-degrading enzymes.

For starch metabolism to take place correctly, various enzymes and proteins acting on the starch granule surface are crucial. Recently, two non-catalytic starch-binding proteins, pivotal for normal starch turnover in Arabidopsis leaves, namely, EARLY STARVATION 1 (ESV1) and its homolog LIKE EARLY STARVATION 1 (LESV), have been identified. Both share nearly 38% sequence homology. As ESV1 has been found to influence glucan phosphorylation via two starch-related dikinases, α-glucan, water dikinase (GWD) and phosphoglucan, water dikinase (PWD), through modulating the surface glucan structures of the starch granules and thus affecting starch degradation, we assess the impact of its homolog LESV on starch metabolism. Thus, the 65-kDa recombinant protein LESV and the 50-kDa ESV1 were analyzed regarding their influence on the action of GWD and PWD on the surface of the starch granules. We included starches from various sources and additionally assessed the effect of these non-enzymatic proteins on other starch-related enzymes, such as starch synthases (SSI and SSIII), starch phosphorylases (PHS1), isoamylase and β-amylase. The data obtained indicate that starch phosphorylation, hydrolyses and synthesis were affected by LESV and ESV1. Furthermore, incubation with LESV and ESV1 together exerted an additive effect on starch phosphorylation. In addition, a stable alteration of the glucan structures at the starch granule surface following treatment with LESV and ESV1 was observed. Here, we discuss all the observed changes that point to modifications in the glucan structures at the surface of the native starch granules and present a model to explain the existing processes.

Emerging Roles of β-Glucanases in Plant Development and Adaptative Responses

Plant β-glucanases are enzymes involved in the synthesis, remodelling and turnover of cell wall components during multiple physiological processes. Based on the type of the glycoside bond they cleave, plant β-glucanases have been grouped into three categories: (i) β-1,4-glucanases degrade cellulose and other polysaccharides containing 1,4-glycosidic bonds to remodel and disassemble the wall during cell growth. (ii) β-1,3-glucanases are responsible for the mobilization of callose, governing the symplastic trafficking through plasmodesmata. (iii) β-1,3-1,4-glucanases degrade mixed linkage glucan, a transient wall polysaccharide found in cereals, which is broken down to obtain energy during rapid seedling growth. In addition to their roles in the turnover of self-glucan structures, plant β-glucanases are crucial in regulating the outcome in symbiotic and hostile plant–microbe interactions by degrading non-self glucan structures. Plants use these enzymes to hydrolyse β-glucans found in the walls of microbes, not only by contributing to a local antimicrobial defence barrier, but also by generating signalling glucans triggering the activation of global responses. As a counterpart, microbes developed strategies to hijack plant β-glucanases to their advantage to successfully colonize plant tissues. This review outlines our current understanding on plant β-glucanases, with a particular focus on the latest advances on their roles in adaptative responses.

Controlling the Fine Structure of Glycogen-like Glucan by Rational Enzymatic Synthesis.

Glycogen-like glucan (GnG), a hyperbranched glucose polymer, has been receiving increasing attention to generate synthetic polymers and nanoparticles. Importantly, different branching patterns strongly influence the functionality of GnG. To uncover ways of obtaining different GnG branching patterns, a series of GnG with radius from 22.03 to 27.06 nm were synthesized using sucrose phosphorylase, α-glucan phosphorylase (GP), and branching enzyme (BE). Adjusting the relative activity ratio of GP and BE (GP/BE) made the molecular weight (MW) distribution of intermediate GnG products follow two different paths. At a low GP/BE, the GnG developed from "small to large" during the synthetic process, with the MW increasing from 6.15 × 106 to 1.21 × 107 g/mol, and possessed a compact structure. By contrast, a high GP/BE caused the "large to small" model, with the MW reduction of GnG from 1.62 × 107 to 1.21 × 107 g/mol, and created a loose external structure. The higher GP activity promoted the elongation of external chains and restrained chain transfer by the BE to the inner zone of GnG, which would modulate the loose-tight structure of GnG. These findings provide new useful insights into the construction of structurally well-defined nanoparticles.

Changes of structures and biosynthesis/hydrolysis-associated genes expression of glucans at different Volvariella volvacea maturity stages

In the present study, effects of maturity stage on structural characteristics and biosynthesis/hydrolysis-associated genes expression of glucans from Volvariella volvacea fruit body were well investigated. Elongation and pileus expansion stages decreased total soluble carbohydrate and protein contents to 17.09 mg/g and 8.33 mg/g, and significantly accumulated the total amino acids contents to 32.37 mg/g. Yields of crude polysaccharides significantly increased to 8.12% at egg stage and decreased to 3.72% at pileus expansion stage. Purified VVP I-a and VVP I-b were proved to be α-glucans. The maturity process affected the monosaccharide compositions, decreased the molecular weights of VVP I-a and VVP I-b with decreased transcription levels of glucan biosynthesis-associated enzyme genes vvugp and vvgls and increased glucan hydrolysis-associated glucanase gene vvexg2 expression with no significant effects on backbone structures including glycosidic linkages and configurations. The findings would benefit for understanding change patterns of V. volvacea glucan structures and their biosynthesis/hydrolysis-associated genes expression at maturity stages.

Reduction of antibiotic-induced biofilm accumulation of Pseudomonas aeruginosa by quaternized phytoglycogen.

Biofilms are oft cited as a factor in the unwanted persistence and recalcitrance of microbial life and a strong research initiative exists to identify, understand, and target vulnerabilities. Phytoglycogen is a biodegradable nanoparticulate biomaterial that is purified from crop plants. Importantly, the highly branched glucan structure provides a scaffold on which to construct novel polymers. Functionalized phytoglycogen (FP) was synthesized using green chemistry principles. Screening of several molecules identified a form of quaternized phytoglycogen which reduced biofilm formation and accretion by Pseudomonas aeruginosa. Exposing P. aeruginosa to modified phytoglycogen and antibiotic in combination not only substantively reduced biofilms, but also prevented increased biofilm formation, a biological response to suboptimal antibiotic concentrations. Treatment of pregrown biofilms with sub-minimum inhibitory concentration antibiotic alone also led to increased proliferation, whereas FP-antibiotic combinations prevented or reduced the extent of this. Swimming, swarming and twitching motility, all critical for biofilm development, were negatively affected by FP. This work supports phytoglycogen as a promising foundational molecule for novel polymers, including those with anti-biofilm function. Critically, in addition to published reports on how suboptimal antibiotic concentrations promote biofilm formation, we demonstrated a similar effect upon pre-existing biofilms, indicating a further route for the failure of antibiotic therapies.

Research On The Composition And Structure Of Β -Glucans Isolated From Basidiomycete Raw Materials Inonotus Hispidus

This article highlights the conducted researches on the composition and structure of β-glucans isolated from the basidiomycete raw material Inonotus hispidus. By means of using the alditol acetate method, as well as by UV and IR methods, one-dimensional (13C NMR, 1H NMR), two-dimensional (1H-1H COSY, 1H-13C HSQC) NMR spectroscopy, the composition and molecular structure of polysaccharides were determined and their branching was proved. It was clarified that the composition of the polysaccharide fractions consists mainly of glucose residues (68-100%), as well as residues of fructose, xylose, mannose and galactose as minor monosaccharides. NMR spectroscopic studies of the specimens showed that the obtained polysaccharides consist of branched glucan structures linked by α- and β-glycosidic bonds. In the structure of β-glucans, the main chain is linked mainly through β-1,3-, partially β-1,4-glycosidic bonds, the branched parts consist of one or more β-D-glucose residues that are linked β-1,3- glycosidic bonds, as well as with the main chain, mainly through α- or β-1,6-glycosidic bonds. The results of the study of molecular parameters showed that the MW of β-glucans of basidiomycetes are in the range of 9100-9900 Da, MWD - 1.2-1.5.

Molecular rotor as a structural probe of glucan polymers: Amylopectin, phytoglycogen, and their β-limit dextrins as models

Fluorescence emissions of molecular rotors (MRs) are affected by local restrictions to molecular motion, and therefore it was considered that MRs can be used as structural probes of biopolymers. In this study, 9-(2-carboxy-2-cyanovinyl)-julolidine (CCVJ), a hydrophilic MR, was used to differentiate branched α-D-glucans, including amylopectin, phytoglycogen, and their β-limit dextrins. CCVJ emissions of glucan dispersions were correlated with dispersion viscosities and glucan branch structures. In diluted glucan dispersions, CCVJ emission showed essentially linear correlation with glucan content. In concentrated glucan dispersions, CCVJ emission correlated with viscosity in a double-logarithmic linear pattern, with phytoglycogen showing much greater sensitivities than amylopectin. In the plots of CCVJ emission vs. molar amount of branch, phytoglycogen materials showed greater slopes than their amylopectin counterparts, suggesting evident effects of branch structure on the restrictions to CCVJ molecules. Overall, CCVJ has demonstrated its fluorescent sensitivity with glucans, showing strong potentials as a structural probe of biopolymers.