Neutral Sugars (neutral + sugar)

Distribution by Scientific Domains


Selected Abstracts


Characterization and Origin of Dissolved Organic Carbon in Yegua Ground Water in Brazos County, Texas

GROUND WATER, Issue 5 2001
Joyanto Routh
Dissolved organic carbon (DOC) concentrations in five shallow (< 20 m) and three deeper wells (27 to 30 m) in the Eocene Yegua Formation (Brazos County in east-central Texas) ranged from 92 to 500 ,m. Characterization of high, intermediate, and low molecular weight DOC fractions (HMW > 3000 amu, IMW 1000 to 3000 amu, and LMW 500 to 1000 amu) and combined neutral sugar analyses provide information on organic matter sources in the Yegua aquifers. Combined neutral sugars ranged in concentration from 0.6 to 2.7 ,mol/L and comprised 0.8% to 6.7% of DOC in ground water. Glucose was the most abundant neutral sugar, followed by xylose and galactose, arabinose, mannose, rhamnose, and fucose. These combined neutral sugars were more diagenetically altered in shallow, oxic ground water as indicated by high mole % fucose + rhamnose and low neutral sugar yield. The precursors for neutral sugars are most probably angiosperm leaves, which show a similar distribution pattern of neutral sugars. Ground water DOC was depleted in 13C relative to soil-zone organic matter (OM) (,16, to ,19,). The ,13C values of bulk DOC and HMW DOC ranged from ,24, to ,32,, whereas LMW and IMW DOC ranged from ,32, to ,34, and ,16, to ,28,, respectively. This variability in ,13C values is probably related to microbial processes and selective preservation of OM. Carbon isotope analyses in bulk and different molecular weight DOC fractions imply a predominantly C3 OM source and a low contribution of soil-zone OM to DOC. [source]


GLYCOSIDASE INHIBITORY ACTIVITY AND ANTIOXIDANT PROPERTIES OF A POLYSACCHARIDE FROM THE MUSHROOM INONOTUS OBLIQUUS

JOURNAL OF FOOD BIOCHEMISTRY, Issue 2010
HAIXIA CHEN
ABSTRACT A water-soluble polysaccharide from Inonotus obliquus (IOPS) was isolated from the mushroom Inonotus obliquus (Fr.) Pilat. The chemical compositions, molecular weight and inhibitory activities on glycosidase and antioxidant properties of IOPS were investigated. The results indicated that IOPS was an acid protein-bound polysaccharide, with a molecular weight of 1.7 × 104 Da and the contents of neutral sugar, protein and uronic acids being 42.5, 18.5 and 6.1%, respectively. IOPS exhibited an inhibitory activity against ,-glucosidase with the IC50 value of 93.3 µg/mL, whereas it had no effective inhibition on ,-amylase. Results of antioxidant activity assays revealed that IOPS had inhibitory activity on the concentration-dependent quenching of 1,1-Diphenyl-2-picrylhydrazyl and hydroxyl radicals. Furthermore, IOPS inhibited the formation of thiobarbituric acid-reactive substances in Fe2+/ascorbate-induced lipid peroxidation in rat liver tissue. These results clearly demonstrated that IOPS was one of the main bioactive components of I. obliquus that contributed to hypoglycemic activity and antioxidant activity. PRACTICAL APPLICATIONS Diabetes mellitus is one of the primary threats to human health because of its increasing prevalence, chronic course and disabling complications. Postprandial hyperglycemia plays an important role in the development of type 2 diabetes mellitus and complications associated with the disease. One therapeutic approach to decrease postprandial hyperglycemia is to retard the absorption of glucose through inhibition of carbohydrate-hydrolyzing enzymes in the digestive organs. In this study, a polysaccharide isolated from the mushroom Inonotus obliquus (IOPS) was shown to have notable glycosidase inhibitory effects and antioxidant activities. This research will benefit for the investigation of effective and safe ,-glucosidase inhibitors from natural materials. IOPS could be a good candidate for application in food and medicinal fields. It might be developed for functional food or lead compounds for use in antidiabetes. [source]


An Acyclic Aminonaphthyridine-Based Receptor for Carbohydrate Recognition: Binding Studies in Competitive Solvents

EUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 22 2007
Monika Mazik
Abstract 1H NMR spectroscopic and microcalorimetric titrations revealed that receptor 3b, consisting of three protonated 2-amino-1,8-naphthyridine units, binds N -acetylneuraminic acid (Neu5Ac), the most commonly occurring sialic acid, with high affinity in competitive solvents such as water/dimethyl sulfoxide. Receptor 3b is able to form neutral/charge-reinforced hydrogen bonds and ion pairs with Neu5Ac, similar to sialic acid-binding proteins. Furthermore, indications for weak binding of neutral sugars, such as methyl ,- D -glucopyranoside, D -maltose and D -cellobiose were provided by NMR spectroscopy. Molecular modelling calculations, synthesis and binding studies in aqueous media are described. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007) [source]


Characterization and Origin of Dissolved Organic Carbon in Yegua Ground Water in Brazos County, Texas

GROUND WATER, Issue 5 2001
Joyanto Routh
Dissolved organic carbon (DOC) concentrations in five shallow (< 20 m) and three deeper wells (27 to 30 m) in the Eocene Yegua Formation (Brazos County in east-central Texas) ranged from 92 to 500 ,m. Characterization of high, intermediate, and low molecular weight DOC fractions (HMW > 3000 amu, IMW 1000 to 3000 amu, and LMW 500 to 1000 amu) and combined neutral sugar analyses provide information on organic matter sources in the Yegua aquifers. Combined neutral sugars ranged in concentration from 0.6 to 2.7 ,mol/L and comprised 0.8% to 6.7% of DOC in ground water. Glucose was the most abundant neutral sugar, followed by xylose and galactose, arabinose, mannose, rhamnose, and fucose. These combined neutral sugars were more diagenetically altered in shallow, oxic ground water as indicated by high mole % fucose + rhamnose and low neutral sugar yield. The precursors for neutral sugars are most probably angiosperm leaves, which show a similar distribution pattern of neutral sugars. Ground water DOC was depleted in 13C relative to soil-zone organic matter (OM) (,16, to ,19,). The ,13C values of bulk DOC and HMW DOC ranged from ,24, to ,32,, whereas LMW and IMW DOC ranged from ,32, to ,34, and ,16, to ,28,, respectively. This variability in ,13C values is probably related to microbial processes and selective preservation of OM. Carbon isotope analyses in bulk and different molecular weight DOC fractions imply a predominantly C3 OM source and a low contribution of soil-zone OM to DOC. [source]


Characterization of extracellular polymers synthesized by tropical intertidal biofilm bacteria

JOURNAL OF APPLIED MICROBIOLOGY, Issue 1 2007
B.O. Ortega-Morales
Abstract Aim:, This study was performed to determine the potential of tropical intertidal biofilm bacteria as a source of novel exopolymers (EPS). Methods and Results:, A screening procedure was implemented to detect EPS-producing biofilm bacteria. Isolates MC3B-10 and MC6B-22, identified respectively as a Microbacterium species and Bacillus species by 16S rDNA and cellular fatty acids analyses, produced different EPS, as evidenced by colorimetric and gas chromatographic analyses. The polymer produced by isolate MC3B-10 displays significant surfactant activity, and may chelate calcium as evidenced by spectroscopic analysis. Conclusions:, Polymer MC3B-10 appears to be a glycoprotein, while EPS MC6B-22 seems to be a true polysaccharide dominated by neutral sugars but with significant concentrations of uronic acids and hexosamines. EPS MC3B-10 possesses a higher surfactant activity than that of commercial surfactants, and given its anionic nature, may chelate cations thus proving useful in bioremediation. The chemical composition of polymer MC6B-22 suggests its potential biomedical application in tissue regeneration. Significance and Impact of the Study:, This is the first report of a Microbacterium species producing EPS with surfactant properties, which expands our knowledge of the micro-organisms capable of producing these biomolecules. Furthermore, this work shows that tropical intertidal environments are a nonpreviously recognized habitat for bioprospecting EPS-producing bacteria, and that these molecules might be involved in ecological roles protecting the cells against dessication. [source]


The RhaS activator controls the Erwinia chrysanthemi 3937 genes rhiN, rhiT and rhiE involved in rhamnogalacturonan catabolism

MOLECULAR MICROBIOLOGY, Issue 5 2004
Nicole Hugouvieux-Cotte-Pattat
Summary Erwinia chrysanthemi causes soft-rot diseases of various plants by enzymatic degradation of the pectin in plant cell walls. The linear regions of pectin are composed of an acidic sugar, d -galacturonic acid. The ramified regions of pectin also include neutral sugars, and are rich in l -rhamnose residues. E. chrysanthemi is able to degrade these polysaccharides, polygalacturonate and rhamnogalacturonate. In E. chrysanthemi, the production of pectinases acting on linear regions is induced in the presence of polygalacturonate by a mechanism involving the repressor KdgR. The induction of the two adjacent E. chrysanthemi genes, designated rhiT and rhiN, is maximal after the simultaneous addition of both polygalacturonate and l -rhamnose. The rhiT product is homologous to the oligogalacturonide transporter TogT of E. chrysanthemi. The rhiN product is homologous to various proteins of unknown function, including a protein encoded by the plant-inducible locus picA of Agrobacterium tumefaciens. Both rhiT and rhiN are highly induced during plant infection. Various data suggest that RhiT and RhiN are involved in rhamnogalacturonate catabolism. RhiN is able to degrade the oligomers liberated by the rhamnogalacturonate lyase RhiE. The induction of the rhiTN operon in the presence of polygalacturonate results from control by the repressor KdgR. The additional induction of these genes by rhamnose is directly mediated by RhaS, a protein homologous to the activator of rhamnose catabolism in Escherichia coli. The virulence of an E. chrysanthemi rhaS mutant towards different host plants was clearly reduced. In this phytopathogenic bacterial species, RhaS positively regulates the transcription of the rhaBAD operon, involved in rhamnose catabolism, of the rhiE gene and of the rhiTN operon. The regulator RhaS plays a larger role in E. chrysanthemi than in other enterobacteria. Indeed, the RhaS control is not restricted to the catabolism of rhamnose but is extended to the degradation of plant polysaccharides that contain this sugar. [source]


Barley polyamine oxidase: characterisation and analysis of the cofactor and the N-terminal amino acid sequence

PHYTOCHEMICAL ANALYSIS, Issue 3 2001
Anna Radová
Abstract This paper reports the first purification method developed for the isolation of an homogeneous polyamine oxidase (PAO) from etiolated barley seedlings. The crude enzyme preparation was obtained after initial precipitation of the extract with protamine sulphate and ammonium sulphate. The enzyme was further purified to a final homogeneity (by the criteria of isoelectric focusing and SDS,PAGE) using techniques of low pressure chromatography followed by two FPLC steps. The purified yellow enzyme showed visible absorption maxima of a flavoprotein at 380 and 450,nm: the presence of FAD as the cofactor was further confirmed by measuring the fluorescence spectra. Barley PAO is an acidic protein (pI 5.4) containing 3% of neutral sugars: its molecular mass determined by SDS,PAGE was 56,kDa, whilst gel permeation chromatography revealed the higher value of 76 kDa. The N-terminal amino acid sequence of barley PAO shows a high degree of similarity to that of maize PAO and to several other flavoprotein oxidases. The polyamines spermine and spermidine were the only two substrates of the enzyme with Km values 4,×,10,5 and 3,×,10,5,M and pH optima of 5.0 and 6.0, respectively. Barley polyamine oxidase is markedly inhibited by acridine dyes and hydrazines. Weak inhibition was observed with substrate analogues, aminoaldehydes, metal chelating agents and several other compounds. Copyright © 2001 John Wiley & Sons, Ltd. [source]