D-glucopyranose Residues Research Articles

β-Cyclodextrin-Stabilized Silver Nanoparticle Production Combined with Loop-Mediated Isothermal Amplification for the Visual Detection of Contagious Pathogens.

β-cyclodextrin (β-CD) is a water-soluble, non-toxic, biocompatible, and cage compound that contains six, seven, or eight α-(1-4)-attached D-glucopyranose residues. The hydroxyl group in the β-CD is responsible for the reduction of metal ions as well as stabilizing the nanoparticles. In this study, we developed a colorimetric assay for identifying contagious pathogens such as SARS-CoV-2 and Enterococcus faecium (E. faecium) via in situ development of β-CD-stabilized silver nanoparticles (AgNPs). In the process, the LAMP amplicons produced a complex with silver nitrate (LAMP amplicon-Ag+) which was reduced when heated at 65 °C for 5 min in the presence of β-CD and developed a brown color. The limit of detection was determined to be approximately 101 CFU mL-1 and 10 fg µL-1 for E. faecium and SARS-CoV-2, respectively. Significantly, the colorimetric examination of contagious diseases was completed in less than 50 min, including the LAMP assay and detection process. Owing to the high sensitivity and rapid readout mechanism of the β-CD-stabilized AgNP-based colorimetric assay, it is anticipated that the introduced method can be efficiently utilized as a versatile point-of-care testing (POCT) platform for molecular diagnostics in resource-limited areas.

New two-stage pH combined with dissolved oxygen control strategy for cyclic β-1,2 glucans synthesis.

On the basis of a novel two-stage pH combined with dissolved oxygen (DO) control strategy in fed-batch fermentation, this research addresses the influence of pH on cyclic β-1,2-glucans (CβGs) biosynthesis and melanin accumulation during the production of CβGs by Rhizobium radiobacter ATCC 13,333. Under these optimal fermentation conditions, the maximum cell concentration and CβGs concentration in a 7-L stirred-tank fermenter were 7.94gL-1 and 3.12gL-1, which were the maximum production reported for R. radiobacter. The melanin concentration of the fermentation broth was maintained at a low level, which was beneficial to the subsequent separation and purification of the CβGs. In addition, a neutral extracellular oligosaccharide (COGs-1) purified by the two-stage pH combined with DO control strategy fermentation medium was structurally characterized. Structural analyses indicated that COGs-1 was a family of unbranched cyclic oligosaccharides composed of only β-1,2-linked D-glucopyranose residues with degree of polymerization between 17 and 23, namely CβGs. This research provides a reliable source of CβGs and structural basis for further studies of biological activity and function. KEY POINTS: • A two-stage pH combined with DO control strategy was proposed for CβGs production and melanin biosynthesis by Rhizobium radiobacter. • The final extracellular CβGs production reached 3.12 gL-1, which was the highest achieved by Rhizobium radiobacter. • The existence of CβGs could be detected by TLC quickly and accurately.

Insights into the mechanism(s) of digestion of crystalline cellulose by plant class C GH9 endoglucanases

Biofuels such as γ-valerolactone, bioethanol, and biodiesel are derived from potentially fermentable cellulose and vegetable oils. Plant class C GH9 endoglucanases are CBM49-encompassing hydrolases that cleave the β (1 → 4) glycosidic linkage of contiguous D-glucopyranose residues of crystalline cellulose. Here, I analyse 3D-homology models of characterised and putative class C enzymes to glean insights into the contribution of the GH9, linker, and CBM49 to the mechanism(s) of crystalline cellulose digestion. Crystalline cellulose may be accommodated in a surface groove which is imperfectly bounded by the GH9_CBM49, GH9_linker, and linker_CBM49 surfaces and thence digested in a solvent accessible subsurface cavity. The physical dimensions and distortions thereof, of the groove, are mediated in part by the bulky side chains of aromatic amino acids that comprise it and may also result in a strained geometry of the bound cellulose polymer. These data along with an almost complete absence of measurable cavities, along with poorly conserved, hydrophobic, and heterogeneous amino acid composition, increased atomic motion of the CBM49_linker junction, and docking experiements with ligands of lower degrees of polymerization suggests a modulatory rather than direct role for CBM49 in catalysis. Crystalline cellulose is the de facto substrate for CBM-containing plant and non-plant GH9 enzymes, a finding supported by exceptional sequence- and structural-homology. However, despite the implied similarity in general acid-base catalysis of crystalline cellulose, this study also highlights qualitative differences in substrate binding and glycosidic bond cleavage amongst class C members. Results presented may aid the development of novel plant-based GH9 endoglucanases that could extract and utilise potential fermentable carbohydrates from biomass.Graphical Crystalline cellulose digestion by plant class C GH9 endoglucanases - an in silico assessment of function.

Enzymatic synthesis of novel oligosaccharides from N-acetylsucrosamine and melibiose using Aspergillus niger α-galactosidase, and properties of the products.

Two kinds of oligosaccharides, N-acetylraffinosamine (RafNAc) and N-acetylplanteosamine (PlaNAc), were synthesized from N-acetylsucrosamine and melibiose using the transgalactosylation activity of Aspergillus niger α-galactosidase. RafNAc and PlaNAc are novel trisaccharides in which d-glucopyranose residues in raffinose (Raf) and planteose are replaced with N-acetyl-d-glucosamine. These trisaccharides were more stable in acidic solution than Raf. RafNAc was hydrolyzed more rapidly than Raf by α-galactosidase of green coffee bean. In contrast, RafNAc was not hydrolyzed by Saccharomyces cerevisiae invertase, although Raf was hydrolyzed well by this enzyme. These results indicate that the physicochemical properties and steric structure of RafNAc differ considerably from those of Raf.

In silico Identification and Taxonomic Distribution of Plant Class C GH9 Endoglucanases

The glycoside hydrolase 9 superfamily, mainly comprising the endoglucanases, is represented in all three domains of life. The current division of GH9 enzymes, into three subclasses, namely A, B, and C, is centered on parameters derived from sequence information alone. However, this classification is ambiguous, and is limited by the paralogous ancestry of classes B and C endoglucanases, and paucity of biochemical and structural data. Here, we extend this classification schema to putative GH9 endoglucanases present in green plants, with an emphasis on identifying novel members of the class C subset. These enzymes cleave the β(1 → 4) linkage between non-terminal adjacent D-glucopyranose residues, in both, amorphous and crystalline regions of cellulose. We utilized non redundant plant GH9 enzymes with characterized molecular data, as the training set to construct Hidden Markov Models (HMMs) and train an Artificial Neural Network (ANN). The parameters that were used for predicting dominant enzyme function, were derived from this training set, and subsequently refined on 147 sequences with available expression data. Our knowledge-based approach, can ascribe differential endoglucanase activity (A, B, or C) to a query sequence with high confidence, and was used to construct a local repository of class C GH9 endoglucanases (GH9C = 241) from 32 sequenced green plants.

Водорастворимые глюканы семян кардамона настоящегоElettaria cardamomum

Water-soluble polysaccharides from seeds of true cardamom (Elettaria cardamomum White at Maton, family Zingiberaceae) have been studied. The study has shown the presence of neutral and acidic components in these polysaccharides. Three polysaccharides (380, 166, and 27 kDa) have been isolated from the neutral fraction. According to the structural analysis data, they represent alpha-glucans with different degrees of branching (7.1-46.1%); alpha-(1-->4)-D-glucopyranose residues of their backbone chains are substituted at the C6 position with single a-D-glucopyranose residues. Polysaccharides with such structures have a wide range of biological activity. The presence of branched alpha-glucans in E. cardamomum seeds has been demonstrated.

Structure elucidation and antioxidant activity of a novel polysaccharide isolated from Tricholoma matsutake

In this study, structural features of Tricholoma matsutake polysaccharide (TMP-A) were investigated by a combination of infrared (IR) spectra, gas chromatography–mass spectrometry (GC–MS), nuclear magnetic resonance (NMR) spectroscopy. The results indicated that TMP-A had a backbone of 1,4-β- d-glucopyranose residue which branches at O-6 based on the experimental results. The branches were mainly composed of an (1 → 3)-α- d-galactopyranose residue, and terminated with α- d-xylopyranose residue. The antioxidant activity of TMP-A was evaluated with several biochemical methods, including DPPH − radical scavenging, hydrogen peroxide scavenging, superoxide anion radical scavenging. The results indicated that TMP-A showed strong antioxidant. In the in vitro antioxidant assay by MTT method, TMP-A could attenuate PC12 cell damage significantly caused by hydrogen peroxide.

Structure of the cell wall polysaccharides of probiotic bifidobacteria Bifidobacteriumbifidum BIM B-465

The composition and structure of cell wall polysaccharides of a biotechnologically promising probiotic strain of bifidobacteria Bifidobacterium bifidum BIM B-465 were established by monosaccharide and methylation analyses along with 2D 1H– 1H homonuclear and 1H– 13C heteronuclear correlation NMR spectroscopy. The major polysaccharide represents a branched glucogalactan consisting of heptasaccharide repeating units having the following structure: [Display omitted] The second isolated polysaccharide is a branched glucan with the main chain of (1→6)-linked α- d-glucopyranose residues, ∼60% of which are 2-substituted with a single α- d-glucopyranosyl group. This polysaccharide is a characteristic of various microorganisms, including some lactobacteria studied earlier.

A Quantum Mechanics/Molecular Mechanics Study of the Protein−Ligand Interaction of Two Potent Inhibitors of Human O-GlcNAcase: PUGNAc and NAG-Thiazoline

O-glycoprotein 2-acetamino-2-deoxy-beta- d-glucopyranosidase ( O-GlcNAcase) hydrolyzes 2-acetamido-2-deoxy-beta- d-glucopyranose ( O-GlcNAc) residues of serine/threonine residues of modified proteins. O-GlcNAc is present in many intracellular proteins and appears to have a role in the etiology of several diseases including cancer, Alzheimer's disease, and type II diabetes. In this work, we have carried out molecular dynamics simulations using a hybrid quantum mechanics/molecular mechanics approach to determine the binding of two potent inhibitors, PUGNAc and NAG, with a bacterial O-GlcNAcase. The results of these simulations show that Asp-401, Asp-298, and Asp-297 residues play an important role in the protein-inhibitor interactions. These results might be useful to design compounds with more interesting inhibitory activity on the basis of its three-dimensional structure.

Influence of cyclodextrins on the proliferation of HaCaT keratinocytes in vitro

Safety and efficacy of pharmaceutical agents can be greatly improved by encapsulation within, or covalent attachment to, a biomaterial carrier. Drug delivery systems must deliver the necessary amount of drug to the targeted site for a necessary period of time, both efficiently and precisely. Various kinds of high-performance biomaterials are being constantly developed for this purpose. Cyclodextrins are potential candidates for such a role, because of their ability to alter physical, chemical, and biological properties of guest molecules through the formation of inclusion complexes. The alpha-, beta-, and gamma-cyclodextrins are widely used natural cyclodextrins, consisting of six, seven, and eight D-glucopyranose residues, respectively, linked by -1,4 glycosidic bonds into a macro cycle. Each cyclodextrin has its own ability to form inclusion complexes with specific guests, an ability, which depends on a proper fit of the guest molecule into the hydrophobic cyclodextrin cavity. The most common pharmaceutical application of cyclodextrins is to enhance the solubility, stability, and bioavailability of drug molecules. Such kinds of ligand-receptor complexes can be used for different applications, e.g., for a transdermal therapeutic system (TTS) or in biofunctional textiles. The aim of this study was the investigation of the influence of the different cyclodextrins on the cell proliferation using HaCaT keratinocytes as an in vitro test system. Moreover, the study was performed to find harmless and nontoxic cyclodextrin concentrations for dermal applications. By means of different independent in vitro tests could be confirmed that alpha-, beta-, and gamma-cyclodextrins in concentrations up to 0.1% (w/v) do not show any antiproliferative influence on HaCaT keratinocytes. Sometimes even proliferative effects could be found. However, all used cyclodextrins (besides gamma-cyclodextrin and its derivatives) in concentrations of 0.5 and 1% (w/v), respectively, exert a cytotoxic influence on the proliferation of HaCaT keratinocytes. On the basis of these findings, the following rank order of cyclodextrins regarding their cytotoxicity was proposed: M-beta-CD > beta-CD > HP-beta-CD > alpha-CD > (gamma-CD). It could be confirmed that beta-CD and M-beta-CD trigger the activity of the effectors caspases -3 and -7. A significant increase of LDH release could be found for beta-CD and methyl-beta-CD in concentrations of 0.5 and 1% (w/v). The calculated cytotoxicity amounted 45 and 79%, respectively. The measurements of the interleukins IL-6 and IL-8 confirmed the findings of the proliferation assays as well as the LDH measurements. These findings may provide further rationale to the use of CDs in topical formulations for dermal and transdermal drug delivery or as raw material to functionalize textiles for medical applications.

Structural characterization of the carbohydrate backbone of the lipooligosaccharide of the marine bacterium Arenibacter certesii strain KMM 3941 T

The structure of the carbohydrate backbone of the lipooligosaccharide (LOS) of the marine bacterium Arenibacter certesii strain KMM 3941 T has been elucidated. The structure was obtained by means of compositional analysis, matrix-assisted laser desorption/ionization mass spectrometry and complete 1H and 13C and 31P NMR spectroscopy. It shows novel and interesting aspects and is the first description of Arenibacter lipopolysaccharides. Strong and mild alkaline treatments, to fully deacylate and only to O-deacylate the LOS were performed in order to determine the core structure. The core consists of a mixture of species differing by the presence of a non-stoichiometric α- d-rhamnose residue. The Kdo unit is substituted at O-5 by α-mannose and at O-4 by a α-galactosyluronic acid phosphate. The lipid A is constituted by a bis-phosphorylated disaccharide unit composed by a 2,3-diamino-2,3-dideoxy-β- d-glucopyranose (DAG) residue as non-reducing end and a GlcN as reducing end. ▪

Synthesis of l-arabinopyranose containing hederagenin saponins

The synthesis of eight hederagenin saponins, five of which are natural products, and their methyl esters is described as part of an ongoing study of the biological activity of triterpenoid saponins. Six disaccharides consisting of an l-arabinopyranose glycosylated in positions 2, 3, or 4 with a β- d-xylopyranose or a β- d-glucopyranose residue, respectively, were synthesized in good to excellent yields. The saponins were then prepared in good yields through glycosylation with a suitably protected hederagenin derivative followed by total deprotection and treatment with diazomethane.

Two-dimensional rotating-frame Overhauser spectroscopy (ROESY) and 13C NMR study of the interactions between maltodextrin and an anionic surfactant

Rotational frame nuclear Overhauser effect spectroscopy (ROESY) and 13C NMR measurements were carried out to study the molecular interaction between maltodextrin, a digestive byproduct of starch, and an anionic surfactant. Significant differences in chemical shifts were observed when sodium dodecyl sulfate (SDS) was introduced into the maltodextrin (DE 10) solutions. 13C NMR measurement indicated that there were downfield shifts and broadening of peaks, especially in the region of 75–81 and 100–103 ppm, which were assigned to carbons 1 and 4 of the d-glucopyranose residues of maltodextrin, respectively. ROESY spectra indicated cross-peaks between the SDS and maltodextrin protons. These peaks can arise only in the case of the designated SDS protons and maltodextrin protons being less than 0.5 nm apart for a substantial period of time. The most intense cross-peaks are those between the central CH 2 protons of SDS near 1.2 ppm and the maltodextrin protons ranging from 3.5 to 3.9 ppm. The SDS-H3 CH 2 protons were resolved from the bulk of the SDS protons, with peaks and shoulders at 1.25 ppm, which indicated an especially strong interaction of the SDS hydrophobic tail with MD6 and some less intense interactions with MD2, 4, and 5.

Structural characteristics of a bioactive polysaccharide from Sorghum arundinaceum.

A polysaccharide, an alpha-D-glucan with an apparent molecular weight of 6.85 x 10(4), called PSa glucan, was isolated from fresh seeds of Sorghum arundinaceum by fractionation on Sephacryl S-300 HR and Sephadex G-25. Chemical and spectroscopic studies indicated that it has a highly branched glucan type structure composed of alpha-(1-->4) linked D-glucopyranose residues with (1-->3), (1-->6) branching points, and a significant amount of alpha-(1-->6) branching to alpha-(1-->3) linked D-glucopyranose residues. The anti-inflammatory activity of the polysaccharide was performed using the capillary permeability assay.

Structural elucidation and antitumor activity of a fructan from Cyathula officinalis Kuan

A fructan named CoPS3 was isolated from Cyathula officinalis Kuan. The structure of CoPS3 was determined by methylation, by the reductive–cleavage method combined with GC–MS analysis, and both 1D and 2D 1H and 13C NMR spectroscopy. These results show that CoPS3 is a graminans-type fructan that is comprised of a β- d-fructofuranosyl backbone having residues linked (2→1)- and (2→6) with branches and an α- d-glucopyranose residue on the nonreducing end of the fructan chain. Each branch is terminated by a β- d-Fru f residue. Bioassay showed that it could inhibit growth of Lewis pulmonary carcinoma implanted in mice.

Conjugation of meningococcal lipooligosaccharides through their lipid A terminus conserves their inner epitopes and results in conjugate vaccines having improved immunological properties

The importance of conserved inner saccharide epitopes to the immune performance of meningococcal lipooligosaccharide–protein conjugate vaccines was demonstrated in the following experiments. Two different oligosaccharides were obtained by chemical degradations of the same L7 lipooligosaccharide, and both were linked terminally to tetanus toxoid. One was a truncated oligosaccharide in which the inner epitopes were incomplete and was obtained by mild acid hydrolysis of the L7 lipooligosaccharide. This oligosaccharide was conjugated by direct reductive amination through its newly exposed terminal Kdo residue. The second, a full-length oligosaccharide, was obtained by O-deacylation of the L7 lipooligosaccharide, with subsequent removal of phosphate substituents from its lipid A moiety using alkaline phosphatase. This permitted the full-length oligosaccharide to be conjugated directly to tetanus toxoid by reductive amination through its newly exposed terminal 2- N-acyl-2-deoxy- d-glucopyranose residue. Comparison of the immune performance of the two conjugates in mice revealed, that while both were able to induce significant levels of L7-lipooligosaccharide-specific IgG antibody, the conjugate made with the full-length saccharide was able to induce antibodies with increased bactericidal activity against homologous meningococci.

Bioactive polysaccharides from Costus spicatus

Three polysaccharides, glucans with mean M r's of 7.50×10 5, 4.25×10 5 and 2.15×10 5, were isolated from fresh stems of Costus spicatus by fractionation on Sephacryl S-300 HR and Sephadex G-25. Chemical and spectroscopic studies indicated that they have a highly branched glucan type structure composed of α-(1→4) linked d-glucopyranose residues with (1→3), (1→6) branching points, and a small amount of (1→6) branching to α-(1→3) linked d-glucopyranose residues. The polysaccharides inhibit capillary permeability and demonstrate phagocytosis stimulating properties.

Synthesis and conformational analysis of a pentasaccharide corresponding to the cell-wall polysaccharide of the Group A Streptococcus

The synthesis and conformational analysis of a pentasaccharide corresponding to a fragment of the cell-wall polysaccharide (CWPS) of the bacteria Streptococcus Group A are described. The polysaccharide consists of alternating α-(1→2)- and α-(1→3)-linked l-rhamnopyranose (Rha p) residues with branching 2-acetamido-2-deoxy- d-glucopyranose (Glc pNAc) residues linked β-(1→3) to alternate rhamnose rings. The pentasaccharide is of interest as a possible terminal unit on the CWPS, for use in a vaccine. The syntheses employed a trichloroacetimidate glycosyl donor. Molecular dynamics ( md) calculations of the pentasaccharide with the force fields cvff and parm22, both in gas phase and with explicit water present, gave different predictions for the flexibility and preferred conformational space. Metropolis Monte Carlo ( mmc) calculations with the hsea force field were also performed. Experimental data were obtained from 1D transient NOE measurements. Complete build-up curves were compared to those obtained by full relaxation matrix calculations in order to derive a model of the conformation. Overall, the best fit between experimental and calculated data was obtained with mmc simulations using the hsea force field. Molecular dynamics and mmc simulations of a tetrasaccharide corresponding to the Group A-variant polysaccharide, which differs in structure from Group A in lacking the Glc pNAc residues, were also performed for purposes of comparison.

An anti-inflammatory and immunomodulatory polysaccharide from Orbignya phalerata

A polysaccharide, a glucan with mean M r of 1.0×10 6 (MP1), was isolated from the mesocarp of fruits of Orbignya phalerata. Chemical and spectroscopic studies indicated that MP1 has a highly branched glucan type structure composed of α-(1→4) linked d-glucopyranose residues with (3→4), (4→6), and with (3→6) branching points. MP1 enhanced phagocytosis in vivo and exhibited anti-inflammatory activity.

Anti-inflammatory and immunologically active polysaccharides of Periandra mediterranea

Three polysaccharides, glucans with mean M r’s of 1.5 × 10 5, 3.6 × 10 4 and 2.1 × 10 4, were isolated from dried roots of Periandra mediterranea by fractionation on Sephacryl S-300 HR and Sephadex G-25. Chemical and spectroscopic studies indicated that they have a highly branched glucan type structure composed of α-(1→4) linked D-glucopyranose residues with both (3→4) and (4→6) branching points. The polysaccharides enhance phagocytosis in vivo, and exhibit anti-inflammatory activity.