Chemistry of the polysaccharides of the diatom Coscinodiscus nobilis

The extracellular polysaccharide of Coscinodiscus nobilis, a member of the Coscinodiscaceae, contains a highly branched heteropolysaccharide(s) containing fucose, rhamnose, mannose, d-glucose, xylose, d-glucuronic acid, galactose (trace) and half ester sulphate. The positions of linkages between the monosaccharides have been established and evidence for the linkages between d-glucuronic acid and monosaccharides was obtained. The extracellular polysaccharide contained also a chrysolaminaran, but this may have been derived from dead cells. Fucose and mannose occur also in a separate polymer. The diatom contained polysaccharide material consisting of glucose, mannose, fucose and uronic acid residues.     

Identification by NMR spectroscopy of oligosaccharides obtained by acidolysis of the capsular polysaccharides of a thermal biomass

This study deals with the chemical characterization of a capsular polysaccharide (CPS) produced by a thermal biomass largely comprising the cyanobacterium Mastigocladus laminosus. The sugar moiety of this polymer is composed of seven neutral monosaccharides (Rha, Fuc, Ara, Xyl, Man, GIc, Gal) and two uronic acids (GalA, GIcA). Proteins represent 18% of the dry weight of the CPS. Organic acid substituents (acetate, pyruvate, succinate) were also detected and estimated by high-performance liquid chromatography. The presence of sulfate groups (5% w/w) was observed, which represents a relatively rare feature for cyanobacteria. Acidic hydrolysis of the purified polysaccharide led to the isolation of four oligosaccharidic fractions. NMR spectroscopy studies of two of the four purified oligosaccharides allowed them to be identified as: GlcA(1→2)GalA(1→2)Man and GlcA(1→2)βMan(1→4)βGal(1→2)Rha     

Polysaccharide analysis using carbohydrate gel electrophoresis: a method to study plant cell wall polysaccharides and polysaccharide hydrolases.

A method to characterize plant cell wall polysaccharides is presented. The complexity of the polymer structures and the large number of different charged and uncharged monosaccharides that make up plant polysaccharides have previously made analysis technically demanding and laborious. Polysaccharide analysis using carbohydrate gel electrophoresis (PACE) relies on derivatization of reducing ends of sugars and oligosaccharides with a fluorophore, followed by electrophoresis under optimized conditions in polyacrylamide gels. We show that PACE is a sensitive and simple tool for studying the monosaccharide composition of polysaccharides and of cell wall preparations. In combination with specific hydrolases, it can be used to analyze the structure of polysaccharides. Moreover, the specificity and kinetics of the plant polysaccharide hydrolases themselves can be quickly and effectively studied. PACE can detect as little as 500 fmol of monosaccharides and 100 fmol of oligosaccharides, and it is fast and quantitative.     

Production of lactose-free galacto-oligosaccharide mixtures: comparison of two cellobiose dehydrogenases for the selective oxidation of lactose to lactobionic acid

Galacto-oligosaccharides, complex mixtures of various sugars, are produced by transgalactosylation from lactose using beta-galactosidase and are of great interest for food and feed applications because of their prebiotic properties. Most galacto-oligosaccharide preparations currently available in the market contain a significant amount of monosaccharides and lactose. The mixture of galacto-oligosaccharides (GalOS) in this study produced from lactose using recombinant beta-galactosidase from Lactobacillus reuteri contains 48% monosaccharides, 26.5% lactose and 25.5% GalOS. To remove efficiently both monosaccharides and lactose from this GalOS mixture containing significant amounts of prebiotic non-lactose disaccharides, a biocatalytic approach coupled with subsequent chromatographic steps was used. Lactose was first oxidised to lactobionic acid using fungal cellobiose dehydrogenases, and then lactobionic acid and monosaccharides were removed by ion-exchange and size-exclusion chromatography. Two different cellobiose dehydrogenases (CDH), originating from Sclerotium rolfsii and Myriococcum thermophilum, were compared with respect to their applicability for this process. CDH from S. rolfsii showed higher specificity for the substrate lactose, and only few other components of the GalOS mixture were oxidised during prolonged incubation. Since these sugars were only converted once lactose oxidation was almost complete, careful control of the CDH-catalysed reaction will significantly reduce the undesired oxidation, and hence subsequent removal, of any GalOS components. Removal of ions and monosaccharides by the chromatographic steps gave an essentially pure GalOS product, containing less than 0.3% lactose and monosaccharides, in a yield of 60.3%.     

Structure of the O-antigen of Yersinia pseudotuberculosis O:4a revised

The O-specific polysaccharide was isolated by mild acid degradation of the lipopolysaccharide of Yersinia pseudotuberculosis O:4a and studied by NMR spectroscopy, including 2D ROESY and ¹H, ¹³C HMBC experiments. The following structure of the pentasaccharide repeating unit of the polysaccharide was established, which differs from the structure reported earlier [Gorshkova, R. P. et al., Bioorg. Khim. 1983, 9, 1401-1407] in the linkage modes between the monosaccharides: where Tyv stands for 3,6-dideoxy-d-arabino-hexose (tyvelose). The structure of the Y. pseudotuberculosis O:4a antigen resembles that of Y. pseudotuberculosis O:2c, which differs in the presence of abequose (3,6-dideoxy-d-xylo-hexose) in place of tyvelose only.     

Structural Analysis of an Extracellular Polysaccharide Bioflocculant of Klebsiella pneumoniae

The glycoside composition and sequence of an extracellular polysaccharide flocculant of Klebsiella pneumoniae H12 was analyzed. GC and HPLC analysis of the acid-hydrolysate identified its constituent monosaccharides as D-Glc, D-Man, D-Gal, and D-GlcA in an approximate molar ratio of 3.9:1.0:2.3:3.6. To analyze the glycoside sequence, the polysaccharide was partially hydrolyzed by acid and enzyme treatment. GC, HPLC, TLC, MALDI-TOF/MS, and 1H- and 13C- NMR spectroscopy characterized the obtained oligosaccharides.

The results clarified the partial structure of H12 polysaccharide as a linear polymer of a unit of pentasaccharide with a side chain of one D-GlcA to D-Glc moiety (see below). Although the existence of other sequences or other constituent glycosides could not be fully excluded, H12 polysaccharide must be a novel types as such a complicated unit for a polymer has not so far been reported. The partial structure of a H12 polysaccharide flocculant is also discussed in this report.

→4)- α-D-Glcp-(1→2)-α-D-Manp-(1→3)-4,6-Pyr-β-D- 3 Galp-(1→4)-β-D-Galp-(1→ ↓

1 β-D-GlcpA     

In vitro antioxidant activities of sulfated polysaccharide fractions extracted from Corallina officinalis

Sulfated polysaccharides (F1, F2) from seaweed Corallina officinalis were isolated through anion-exchange column chromatography. Their chemical characteristics were determined by GC, HPLC, FT-IR and UV spectra. F1 and F2 contained only two monosaccharides, namely galactose and xylose. The antioxidant activities of F1, F2 and the de-sulfated polysaccharides (DF-1, DF-2) in vitro were investigated, including hydroxyl radicals scavenging effect, superoxide radical scavenging capacity, DPPH radical activity and reducing power. As expected, antioxidant assay showed that the two sulfated polysaccharide fractions (F1, F2) possessed considerable antioxidant properties and had more excellent abilities than de-sulfated polysaccharides (DF-1, DF-2).     

Primary structure and configuration of tea polysaccharide

Polysaccharide is a class of natural macromole-cules of which many species have been found to carry significant biological activities. Although the research on activities of saccharide has been at a lower level in the past comparing to those of proteins and nucleic acids, much progress has been made in recent years because of accelerated activities worldwide[1]. Such progress has been made mostly in areas of structural analysis, and researches on structure-activity relation-ships. The biologic…     

Structure of hemicelluloses isolated from Canavalia ensiformis and Triticum aestivum straws

Hemicellulose was extracted from horse bean and wheat straws in a yield of 5 and 9% respectively. The whole hemicellulose was hydrolysed and the molar ratio of the component monosaccharides was determined. Uronic acid, galactose, glucose, arabinose and xylose were found in both hemicelluloses. The molar ratio of the monosaccharides was determined in each of 4 fractions derived from the saccharide. The main fractions (B and C) were partially hydrolysed and an oligosaccharide containing arabinose and xylose (1:1) was isolated from both hemicelluloses. Another oligosaccharide containing xylose and glucose (2:1) was also isolated from wheat straw hemicellulose. Periodate oxidation was carried out on fractions B and C. The formic acid and the consumed periodate were determined. Each hemicellulose was subjected to Smith's degradation. Glycerol, erythrytol and compounds containing xylose and glycerol (1:1), and xylose and erythrytol (1:1) were isolated.     

Structure of an acidic polysaccharide from the marine bacterium Pseudoalteromonas flavipulchra NCIMB 2033(T)

An acidic polysaccharide was isolated from Pseudoalteromonas flavipulchra type strain NCIMB 2033(T) and found to consist of 6-deoxy-L-talose (L-6dTal), D-galactose and 3-deoxy-D-manno-oct-2-ulosonic acid (Kdo). The identities of the monosaccharides were ascertained by sugar analysis and 1D 1H and 13C NMR spectroscopy in conjunction with 2D COSY, TOCSY, ROESY and 1H, 13C HMQC experiments, which enabled determination of the following structure of the trisaccharide repeating unit of the polysaccharide:-->3)-alpha-L-6dTalp4Ac-(1-->3)-beta-D-Galp-(1-->7)-alpha-Kdop-(2-->.     

Primary structure and configuration of tea polysaccharide

The monosaccharide composition of a tea polysaccharide (TGC) was determined by GC-MS method. Furthermore, the primary structure of tea polysaccharide and its configuration in the aqueous solution were investigated utilizing a combination of classical chemical methods and modern instrumental techniques including GC-MS, Proton NMR, UV and CD. The results indicate that TGC consists of 6 monosaccharides: Rha, Ara, Xyl, Glu, Man and Gal. The configuration of TGC in water solution is proposed to be an ordered helix. The possible primary structure of TGC was outlined as below: the basic structure of the main chain consists of Rha, Glu and Gal units. All three monosaccharides can potentially be connected to branch chains consisting of mainly Ara, and the linkages could be in β1 → 2, β 1 → 3, β 2 → 3 forms. When branch chain is absent in the basic structure of the main chain the linkage consists of only β 1 → 3; Xyl exists at the terminal end of either the main chain or the branch chain with β 1 → linkage.     

Identification of the capsular polysaccharides of Type D and F Pasteurella multocida as unmodified heparin and chondroitin,respectively

Pasteurella multocida is a pathogenic Gram-negative bacterial species that infects a wide variety of animals and humans. A notable morphological feature of many isolates is the extracellular capsule. The ability to remove the capsule by treatment with certain glycosidases has been utilized to discern various capsular types called A, D and F. Based on this preliminary evidence, these microbes have capsules made of glycosaminoglycans, linear polysaccharides composed of repeating disaccharide units containing an amino sugar. Glycosaminoglycans are also abundant components of the vertebrate extracellular matrix. It has been shown previously that the major Type A capsular material was hyaluronan (hyaluronic acid). We report that the Type D polymer is an unmodified heparin (N-acetylheparosan) with a -->4)-beta-D-Glcp-UA-(1-->4)-alpha-D-Glcp-NAc-(1--> repeating unit and the Type F polymer is an unmodified chondroitin with a -->4)-beta-D-Glcp-UA-(1-->3)-beta-D-Galp-NAc-(1--> repeating unit. The monosaccharide compositions, disaccharide profiles, and 1H NMR analyses are consistent with these identifications. The molecular size of the Pasteurella polymers is approximately 100-300 kDa as determined by gel electrophoresis and multi-angle laser light scattering; this size is much greater than the 10-30 kDa size of the analogous polymers isolated from animal tissues. The glycosaminoglycan capsular polymers are relatively non-immunogenic virulence factors that enhance microbial pathogenicity.     

紫球藻多糖化学结构解析

为明确紫球藻多糖的化学结构,本文采用化学分析和光谱分析方法对紫球藻多糖的一级糖链结构进行了分析。GC分析表明该多糖由木糖、葡萄糖和半乳糖组成,为一种杂多糖,其摩尔比为:2.96∶1.25∶3.06;红外光谱分析结果显示紫球藻多糖为硫酸化多糖,糖苷键类型为β构型;化学分析结果推断紫球藻多糖糖链连接方式以1→3为主,存在少量1→2,1→4,1→6键型,且半乳糖在支链或主链末端有较大量的存在,木糖和葡萄糖在主链或靠近主链区域有特定分布;NMR分析显示紫球藻多糖的硫酸酯基连在C-6上,且多糖的糖苷键为β型;GC-MS联机分析进一步确定紫球藻多糖为一种主要含有1→3糖苷键,并含有1→4,1→6糖苷键的杂多糖。综合上述分析,推断出紫球藻多糖的糖链主链的重复单元结构。     

高效液相色谱法分析猪屎豆种子胶多糖中的单糖组成

建立了一种采用SUGAR SP-G 0810(Pb型)糖分析色谱柱,以纯水为流动相,利用示差折光检测器的高效液相色谱外标法直接分离分析半乳甘露聚糖胶中单糖组成的方法。木糖、葡萄糖、半乳糖和甘露糖的分离在20 min内完成,检出限分别达到2.0μg,20μg,1.0μg和20μg,线性范围为2～10 mg/mL。该方法简便、快速、重现性好,用于猪屎豆种子胶多糖中单糖组分的测定,并进行回收率试验,结果5次测定的半乳糖和甘露糖的回收率分别为95.83%和103.68%,RSD分别为1.53%和1.50%。     

The structure of the core region of the lipopolysaccharide from Shewanella algae BrY, containing 8-amino-3,8-dideoxy-D-manno-oct-2-ulosonic acid

The structure of the carbohydrate backbone of the lipid A-core region of the LPS from Shewanella algae strain BrY was analysed. The LPS was N,O-deacylated to give three products, which were isolated and studied by chemical methods, NMR and mass spectrometry: [Carbohydrate structures: see text]. All monosaccharides except L-rhamnose had the D-configuration. This LPS presents a second example (after S. oneidensis) of the structure with a novel linking unit between the core and lipid A moieties, 8-amino-3,8-dideoxy-D-manno-oct-2-ulosonic acid (8-amino-Kdo).     

The CWPS Rubik’s cube: Linking diversity of cell wall polysaccharide structures with the encoded biosynthetic machinery of selected Lactococcus lactis strains

The biosynthetic machinery for cell wall polysaccharide (CWPS) production in lactococci is encoded by a large gene cluster, designated cwps. This locus displays considerable variation among lactococcal genomes, previously prompting a classification into three distinct genotypes (A–C). In the present study, the cwps loci of 107 lactococcal strains were compared, revealing the presence of a fourth cwps genotype (type D). Lactococcal CWPSs are comprised of two saccharidic structures: a peptidoglycan-embedded rhamnan backbone polymer to which a surface-exposed, poly/oligosaccharidic side-chain is covalently linked. Chemical structures of the side-chain of seven lactococcal strains were elucidated, highlighting their diverse and strain-specific nature. Furthermore, a link between cwps genotype and chemical structure was derived based on the number of glycosyltransferase-encoding genes in the cwps cluster and the presence of conserved genes encoding the presumed priming glycosyltransferase. This facilitates predictions of several structural features of lactococcal CWPSs including (a) whether the CWPS possesses short oligo/polysaccharide side-chains, (b) the number of component monosaccharides in a given CWPS structure, (c) the order of monosaccharide incorporation into the repeating units of the side-chain (for C-type strains), (d) the presence of Galf and phosphodiester bonds in the side-chain, and (e) the presence of glycerol phosphate substituents in the side-chain.     

An alkali-soluble heteroxylan from seeds of Phoenix dactylifera L

Alkali-soluble polysaccharides, isolated from the seeds of dates, have been investigated using methylation and partial hydrolysis studies. The polysaccharides are shown to contain D-xylose and 4-O-methyl-D-glucuronic acid in a molar ratio of 5:1. An aldobiouronic acid from hemicellulose was characterized, and investigation revealed that the hemicellulose consists of a polymer of (1-->4)-linked D-xylopranosyl residues having branches of D-xylopyranosyl and 4-O-methyl-alpha-D-glucopyranosyluronic acid.     

Predicting the molecular shape of polysaccharides from dynamic interactions with water

How simple monosaccharides, once polymerized, become the basis for structural materials remains a mystery. A framework is developed to investigate the role of water in the emergence of dynamic structure in polysaccharides, using the important beta(1-->4) linkage as an example. This linkage is studied within decasaccharide fragments of cellulose, chitin, mannan, xylan, and hyaluronan, using molecular simulations in the presence of explicit water solvent. Although cellulose, mannan, chitin, and xylan are chemically similar, their intramolecular hydrogen-bond dynamics and interaction with water are predicted to differ. Cellulose, mannan, and chitin favor relatively static intramolecular hydrogen bonds, xylan prefers dynamic water bridges, and multiple water configurations are predicted at the beta(1-->4) linkages of hyaluronan. With such a variety of predicted dynamics, the hypothesis that the beta(1-->4) linkage is stabilized by intramolecular hydrogen bonds was rejected. Instead, it is proposed that favored molecular configurations are consistent with maximum rotamer and water degrees of freedom, explaining observations made previously by X-ray diffraction. Furthermore, polysaccharides predicted to be conformationally restricted in simulations (cellulose, chitin, and mannan) prefer the solid state in reality, even as oligosaccharides. Those predicted to be more flexible (xylan and hyaluronan) are known to be soluble, even as high polymers. Therefore an intriguing correlation between chemical composition, water organization, polymer properties, and biological function is proposed.     

The structure of the O-specific polysaccharide of the lipopolysaccharide from Pantoea agglomerans strain FL1

A neutral O-specific polysaccharide consisting of d-rhamnose was obtained by mild acid hydrolysis of the lipopolysaccharide of the plant pathogenic bacterium Pantoea agglomerans strain FL1, a common epiphyte of many plant species, and associated with Pseudomonas savastanoi pv. savastanoi in young and apparently intact olive knots. By means of compositional and methylation analyses, and NMR spectroscopy, the chemical repeating unit of the polymer was identified as a linear tetrasaccharide of the structure: