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Uronic Acid (uronic + acid)
Selected AbstractsIn vitro degradation of forage chicory (Cichorium intybus L.) by endopoly- galacturonaseJOURNAL OF THE SCIENCE OF FOOD AND AGRICULTURE, Issue 15 2007Xuezhao Sun Abstract BACKGROUND: Leaves of forage chicory break down rapidly in the rumen despite little or no rumination. Because chicory cell walls contain high concentrations of pectin, degradation of leaf midrib and leaf lamina tissues by pectinolytic enzymes was investigated. RESULTS: Treatment with endopolygalacturonase (endo-PG) degraded fresh intact chicory leaves to particles of less than 1 mm in length and solubilised more than 70% of the dry matter within 16 h. Uronic acids were released more extensively than neutral monosaccharides. In similar treatments, 77% of white clover leaflets and 12% of perennial ryegrass leaf blades were solubilised or broken down to particles with a size of less than 1 mm. The degradation of pectic polysaccharides in chicory midribs was monitored by immunofluorescence labelling with monoclonal antibodies JIM5 and JIM7 which target partially methyl-esterified epitopes of the homogalacturonan (HG) domain of pectin. Examination by fluorescence microscopy revealed that cell separation in the cortical parenchyma of chicory midrib following endo-PG treatment was associated with loss of HG from the middle lamella, the corners of intercellular spaces and from the tricellular junctions. CONCLUSION: The results of the current study suggest that one of the main contributions to chicory breakdown in the rumen may be cell separation caused by degradation of HG by pectinolytic enzymes from rumen bacteria. Copyright © 2007 Society of Chemical Industry [source] Evaluation of the extraction efficiency for polyphenol extracts from by-products of green kiwifruit juicingINTERNATIONAL JOURNAL OF FOOD SCIENCE & TECHNOLOGY, Issue 12 2009Dongxiao Sun-Waterhouse Summary The health benefits of fruits are attributable in part to their bioactive components such as phenolics and pectic polysaccharides. By-products derived from kiwifruit processing can be a good source of such bioactive compounds. Extracts were produced using different concentrations of ethanol in water (0%, 30%, 50%, 74% and 96% v/v) from by-products (skin, residue and pulp) of the green-fleshed kiwifruit (Actinidia deliciosa,Hayward') juicing process. The amounts of phenolic compounds and uronic acid (UA) as well as the phenolic composition in each extract were determined. Results show that different by-products contained different concentrations of phenolics and pectic polysaccharides. Based on total phenolic contents, 96% v/v ethanol appeared to be the best extraction medium. The 30% or 74% ethanolic dilution was the second best medium for phenolic extraction from skin and pulp/residue, respectively. Water was a good medium for extracting satisfactory quantities of phenolics as well as the highest concentration of pectic polysaccharides. Phenolic profiling by high-performance liquid chromatography (HPLC) was used to detect individual phenolic compounds in an extract. Results using HPLC showed that alkali pre-treatment has improved the extraction efficiency of phenolics as a function of alkali concentration, fruit tissue type, extraction media, by-product preparation method, and class of polyphenols. As a result more efficient methods for both extraction and characterisation of polyphenols could be evaluated. [source] Combined Application of Galactose Oxidase and ,- N -Acetylhexosaminidase in the Synthesis of Complex Immunoactive N -Acetyl- D -galactosaminidesADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 7-8 2005Pavla Fialová Abstract A high-yield preparatory procedure for the synthesis of p -nitrophenyl 2-acetamido-2-deoxy-,- D - galacto -hexodialdo-1,5-pyranoside (2) using the galactose oxidase from Dactylium dendroides in a batch reactor was developed. Enzymatic recognition of this aldehyde and the respective uronic acid 3 obtained by NaClO2 oxidation was studied using a set of 36 fungal ,- N -acetylhexosaminidases from Acremonium, Aspergillus, Penicillium and Talaromyces genera. The aldehyde 2 was readily hydrolysed by all tested ,- N -acetylhexosaminidases but neither the uronic acid 3 nor its methyl ester 4 were accepted. Molecular modelling with docking into the active centre of the ,- N -acetylhexosaminidase from Aspergillus oryzae revealed that the aldehyde 2 is processed as a C-6 geminal diol by the enzyme. The aldehyde 2 was tested for transglycosylation reactions using GlcNAc as an acceptor. The ,- N -acetylhexosaminidase from Talaromyces flavus gave the best yields (37%) of the transglycosylation product 2-acetamido-2-deoxy-,- D - galacto -hexodialdo-1,5-pyranosyl-(1,4)-2-acetamido- 2-deoxy- D -glucopyranose, which was oxidised in situ to yield the final product 2-acetamido-2-deoxy-,- D -galactopyranosyluronic acid-(1,4)-2-acetamido-2-deoxy- D -glucopyranose (6). Compounds 3 and 6 were shown to be high-affinity ligands for two natural killer cell activation receptors, NKR-P1A and CD69. For the latter receptor they turned out to be among the best ligands described so far. This increase was obviously due to the presence of a carboxy moiety. [source] EXTRACELLULAR MATRIX ASSEMBLY IN DIATOMS (BACILLARIOPHYCEAE).JOURNAL OF PHYCOLOGY, Issue 2 2006The effects of phosphate (P) limitation, varying salinity (5,65 psu), and solid media growth conditions on the polysaccharides produced by the model diatom, Phaeodactylum tricornutum Bohlin were determined. Sequential extraction was used to separate polymers into colloidal (CL), colloidal extracellular polymeric substances (cEPS), hot water soluble (HW), hot bicarbonate soluble (HB), and hot alkali (HA) soluble fractions. Media-soluble polymers (CL and cEPS) were enriched in 4-linked mannosyl, glucosyl, and galactosyl residues as well as terminal and 3-linked xylosyl residues, whereas HW polymers consisted mainly of 3-linked glucosyl as well as terminal and 2,4-linked glucuronosyl residues. The HB fraction was enriched in terminal and 2-linked rhamnosyl residues derived from the mucilage coating solubilized by this treatment. Hot alkali treatment resulted in the complete dissolution of the frustule releasing 2,3- and 3-linked mannosyl residues. The fusiform morphotype predominated in standard and P-limited cultures and cultures subjected to salinity variations, but growth on solid media resulted in an enrichment of the oval morphotype. The proportion and linkages of 15 residues, including neutral, uronic acid, and O -methylated sugars, varied with environmental conditions. P limitation and salinity changes resulted in 1.5- to 2.5,fold increase in carbohydrate production, with enrichment of highly branched/substituted and terminal rhamnose, xylose, and fucose as well as O -methylated sugars, uronic acids, and sulfate. The increased deoxy- and O -methylated sugar content under unfavorable environments enhances the hydrophobicity of the polymers, whereas the anionic components may play important roles in ionic cross-linking, suggesting that these changes could ameliorate the effects of salinity or P-stress and that these altered polysaccharide characteristics may be useful as bioindicators for environmental stress. [source] Cell wall polysaccharides of bush butter (Dacryodes edulis (G Don) HJ Lam) fruit pulp and their evolution during ripeningJOURNAL OF THE SCIENCE OF FOOD AND AGRICULTURE, Issue 8 2001Crépin Ella Missang Abstract Cell wall material was isolated as alcohol-insoluble solids (AIS) from bush butter endocarp tissue at different stages of ripeness. AIS were then extracted with 0.05,M CDTA followed by increasing concentrations of KOH (0.05, 1 and 4,M respectively). The chemical extractions solubilised a total of 51.6,60.6% of AIS, the yields of CDTA extracts accounting for approximately 9.6,12.2% of AIS. The extracts as well as the residues were analysed for their sugar composition and protein and starch contents. CDTA extracted the bulk of uronic acid in AIS, but the uronic acid content (after dialysis) of these extracts showed a significant decrease as the fruits ripened (from 439 to 252,mg,g,1 between the first and the last degree of ripeness). Analysis of the CDTA extracts by anion exchange and size exclusion chromatography showed a gradual appearance of new pectic populations at low degrees of methylation and low molecular weights, indicating that CDTA-soluble pectins are demethylated and depolymerised during ripening. The dilute alkali (0.05,M KOH) extracts were essentially composed of proteins in addition to a minor quantity of pectin. The 1,M KOH and principally 4,M KOH treatments led to the extraction of hemicelluloses, mainly xyloglucan-like and mannan-like polymers. These extracts also contained substantial amounts of protein and starch. No variation related to the degree of ripeness was visible in the sugar composition of the alkali extracts. The molecular weight distribution of the hemicelluloses did not change with the degree of ripeness. The final residues accounted for 21.4,27.3% of AIS and were mostly composed of glucose (827,908,mg,g,1). All these results suggested that only CDTA-soluble pectins were involved in bush butter fruit softening. © 2001 Society of Chemical Industry [source] Phenolic Hydroxy Groups Incorporated for the Peroxidase-Catalyzed Gelation of a Carboxymethylcellulose Support: Cellular Adhesion and ProliferationMACROMOLECULAR BIOSCIENCE, Issue 3 2009Yuko Ogushi Abstract The effect of Ph-OH group content on gelation time, mechanical properties, hydrophobicity, and cellular adhesiveness of hydrogels produced from carboxymethylcellulose derivatives is investigated. A higher Ph-OH group content induces faster gelation and yields more brittle and hydrophobic gels. After 4 h of seeding, a larger number of L929 fibroblasts adhere to the hydrogel of the CMC-Ph that contains 15.4 Ph-OH groups per 100 repeat units of uronic acid (97% adhesion rate) than to the gel of CMC-Ph with only 8.4 Ph-OH groups (62% adhesion rate). The results demonstrate that controlling the Ph-OH group content is an effective and useful way to control cellular adhesion and proliferation on the hydrogels, as well as gelation time and mechanical properties of the gels. [source] Heating-induced conformational change of a novel ,-(1,3)- D -glucan from Pleurotus geestanusBIOPOLYMERS, Issue 2 2010Mei Zhang Abstract Recently, we isolated and purified a neutral polysaccharide (PGN) from edible fungus Pleurotus geestanus. Its structure was characterized by a range of physical,chemical methods, including high performance anion exchange chromatography, uronic acid, and protein analyses, size exclusion chromatography with ultraviolet, refractive index and light scattering detectors, and nuclear magnetic resonance. Our results revealed that PGN is a novel ,-(1,3)- D -glucan with glucose attached to every other sugar residues at Position 6 in the backbone. It has a degree of branching of 1/2. Such structure is different from typical ,-(1,3)- D -glucans schizophyllan and lentinan in which DB is 1/3 and 2/5, respectively. Rheological study showed a very interesting melting behavior of PGN in water solution: heating PGN in water leads to two transitions, in the range of 8,12.5°C and 25,60°C, respectively. The melting behavior and conformational changes were characterized by rheometry, micro-differential scan calorimetry, atomic force microscopy, static and dynamic light scattering at different temperatures. The first heating-induced transition corresponds to the disintegration of polymer bundles into small helical clusters, resembling the heating-induced dissociation of SPG in water at 7°C; the second one might correspond to the dissociation of helical strands to individual chains. The ability of PGN to undergo a conformation/viscosity transition in water upon heating is very valuable to immobilize cells or enzymes or therapeutic DNA/RNA, which makes PGN a potentially useful biomaterial. © 2009 Wiley Periodicals, Inc. Biopolymers 93: 121,131, 2010. This article was originally published online as an accepted preprint. The "Published Online" date corresponds to the preprint version. You can request a copy of the preprint by emailing the Biopolymers editorial office at biopolymers@wiley.com [source] Characterization of extracellular polymers synthesized by tropical intertidal biofilm bacteriaJOURNAL OF APPLIED MICROBIOLOGY, Issue 1 2007B.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] GLYCOSIDASE INHIBITORY ACTIVITY AND ANTIOXIDANT PROPERTIES OF A POLYSACCHARIDE FROM THE MUSHROOM INONOTUS OBLIQUUSJOURNAL OF FOOD BIOCHEMISTRY, Issue 2010HAIXIA 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] EXTRACELLULAR MATRIX ASSEMBLY IN DIATOMS (BACILLARIOPHYCEAE).JOURNAL OF PHYCOLOGY, Issue 2 2006The effects of phosphate (P) limitation, varying salinity (5,65 psu), and solid media growth conditions on the polysaccharides produced by the model diatom, Phaeodactylum tricornutum Bohlin were determined. Sequential extraction was used to separate polymers into colloidal (CL), colloidal extracellular polymeric substances (cEPS), hot water soluble (HW), hot bicarbonate soluble (HB), and hot alkali (HA) soluble fractions. Media-soluble polymers (CL and cEPS) were enriched in 4-linked mannosyl, glucosyl, and galactosyl residues as well as terminal and 3-linked xylosyl residues, whereas HW polymers consisted mainly of 3-linked glucosyl as well as terminal and 2,4-linked glucuronosyl residues. The HB fraction was enriched in terminal and 2-linked rhamnosyl residues derived from the mucilage coating solubilized by this treatment. Hot alkali treatment resulted in the complete dissolution of the frustule releasing 2,3- and 3-linked mannosyl residues. The fusiform morphotype predominated in standard and P-limited cultures and cultures subjected to salinity variations, but growth on solid media resulted in an enrichment of the oval morphotype. The proportion and linkages of 15 residues, including neutral, uronic acid, and O -methylated sugars, varied with environmental conditions. P limitation and salinity changes resulted in 1.5- to 2.5,fold increase in carbohydrate production, with enrichment of highly branched/substituted and terminal rhamnose, xylose, and fucose as well as O -methylated sugars, uronic acids, and sulfate. The increased deoxy- and O -methylated sugar content under unfavorable environments enhances the hydrophobicity of the polymers, whereas the anionic components may play important roles in ionic cross-linking, suggesting that these changes could ameliorate the effects of salinity or P-stress and that these altered polysaccharide characteristics may be useful as bioindicators for environmental stress. [source] The dual roles of AlgG in C-5-epimerization and secretion of alginate polymers in Pseudomonas aeruginosaMOLECULAR MICROBIOLOGY, Issue 4 2003Sumita Jain Summary Pseudomonas aeruginosa strains causing chronic pulmonary infections in cystic fibrosis patients produce high levels of alginate, an exopolysaccharide that confers a mucoid phenotype. Alginate is a linear polymer of d -mannuronate (M) and variable amounts of its C-5-epimer, l -guluronate (G). AlgG is a periplasmic C-5-epimerase that converts poly d -mannuronate to the mixed M+G sequence of alginate. To understand better the role and mechanism of AlgG activity, a mutant was constructed in the mucoid strain FRD1 with a defined non-polar deletion of algG . Instead of producing poly mannuronate, the algG deletion mutant secreted dialysable uronic acids, as does a mutant lacking the periplasmic protein AlgK. High levels of unsaturated ends and the nuclear magnetic resonance spectroscopy pattern revealed that the small, secreted uronic acids were the products of extensive polymer digestion by AlgL, a periplasmic alginate lyase co-expressed with AlgG and AlgK. Thus, AlgG is bifunctional with (i) epimerase activity and (ii) a role in protecting alginate from degradation by AlgL during transport through the periplasm. AlgK appears to share the second role. AlgG and AlgK may be part of a periplasmic protein complex, or scaffold, that guides alginate polymers to the outer membrane secretin (AlgE). To characterize the epimerase activity of AlgG further, the algG4 allele of poly mannuronate-producing FRD462 was shown to encode a protein lacking only the epimerase function. The sequence of algG4 has a Ser-272 to Asn substitution in a serine,threonine-rich and conserved region of AlgG, which revealed a critical residue for C-5-epimerase activity. [source] In vitro anti-adhesive activity of green tea extract against pathogen adhesionPHYTOTHERAPY RESEARCH, Issue 4 2009Ji-Hye Lee Abstract Camellia sinensis polysaccharide has been reported to possess anti-adhesive activity against pathogens. The present study was designed to investigate whether hot water extracts obtained from green tea leaves might inhibit pathogen adhesion to human or mouse cell lines. Green tea extract-4 (CSI-4) with the maximum yield of 4% (w/v) is composed of a major proportion of carbohydrates containing 40% uronic acids, but lack of catechins. It showed strong inhibitory activities against hemagglutination mediated by pathogens Helicobacter pylori, Propionibacterium acnes and Staphylococcus aureus with the minimum inhibitory concentrations of 0.01-0.5 mg/mL. CSI-4 further demonstrated an inhibitory effect on the adhesion of these pathogens to host cell lines with the IC50 values (50% inhibition of adhesion) of 0.14,2.3 mg/mL. It exhibited the highest activity against P. acnes, but no inhibitory effects were observed against Lactobacillus acidophilus, Bifidobacterium bifidum, Escherichia coli, or Staphylococcus epidermidis. Our results suggest that CSI-4 may exert a selective anti-adhesive effect against certain pathogenic bacteria with no adverse effects against beneficial or commensal bacteria. Copyright © 2008 John Wiley & Sons, Ltd. [source] | |||||||||||||