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Galacturonic Acid (galacturonic + acid)
Selected AbstractsStructural studies of the capsular polysaccharide and lipopolysaccharide O-antigen of Aeromonas salmonicida strain 80204-1 produced under in vitro and in vivo growth conditionsFEBS JOURNAL, Issue 22 2004Zhan Wang Aeromonas salmonicida is a pathogenic aquatic bacterium and the causal agent of furunculosis in salmon. In the course of this study, it was found that when grown in vitro on tryptic soy agar, A. salmonicida strain 80204-1 produced a capsular polysaccharide with the identical structure to that of the lipopolysaccharide O-chain polysaccharide. A combination of 1D and 2D NMR methods, including a series of 1D analogues of 3D experiments, together with capillary electrophoresis-electrospray MS (CE-ES-MS), compositional and methylation analyses and specific modifications was used to determine the structure of these polysaccharides. Both polymers were shown to be composed of linear trisaccharide repeating units consisting of 2-acetamido-2-deoxy- d -galacturonic acid (GalNAcA), 3-[(N -acetyl-L-alanyl)amido]-3,6-dideoxy- d -glucose{3-[(N -acetyl- l -alanyl)amido]-3-deoxy- d -quinovose, Qui3NAlaNAc} and 2-acetamido-2,6-dideoxy- d -glucose (2-acetamido-2-deoxy- d -quinovose, QuiNAc) and having the following structure: [,3)- , - d -GalpNAcA-(1,3)- , - d -QuipNAc-(1,4)- , - d -Quip3NAlaNAc-(1-]n, where GalNAcA is partly presented as an amide and AlaNAc represents N -acetyl- l -alanyl group. CE-ES-MS analysis of CPS and O-chain polysaccharide confirmed that 40% of GalNAcA was present in the amide form. Direct CE-ES-MS/MS analysis of in vivo cultured cells confirmed the formation of a novel polysaccharide, a structure also formed in vitro, which was previously undetectable in bacterial cells grown within implants in fish, and in which GalNAcA was fully amidated. [source] Relationships between the ethanol utilization (alc) pathway and unrelated catabolic pathways in Aspergillus nidulansFEBS JOURNAL, Issue 17 2003Michel Flipphi The ethanol utilization pathway in Aspergillus nidulans is a model system, which has been thoroughly elucidated at the biochemical, genetic and molecular levels. Three main elements are involved: (a) high level expression of the positively autoregulated activator AlcR; (b) the strong promoters of the structural genes for alcohol dehydrogenase (alcA) and aldehyde dehydrogenase (aldA); and (c) powerful activation of AlcR by the physiological inducer, acetaldehyde, produced from growth substrates such as ethanol and l -threonine. We have previously characterized the chemical features of direct inducers of the alc regulon. These studies allowed us to predict which type of carbonyl compounds might induce the system. In this study we have determined that catabolism of different amino acids, such as l -valine, l -isoleucine, l -arginine and l -proline, produces aldehydes that are either not accumulated or fail to induce the alc system. On the other hand, catabolism of d -galacturonic acid and putrescine, during which aldehydes are transiently accumulated, gives rise to induction of the alc genes. We show that the formation of a direct inducer from carboxylic esters does not depend on alcA -encoded alcohol dehydrogenase I or on AlcR, and suggest that a cytochrome P450 might be responsible for the initial formation of a physiological aldehyde inducer. [source] Primary Cell Adhesion on RGD-Functionalized and Covalently Crosslinked Thin Polyelectrolyte Multilayer Films,ADVANCED FUNCTIONAL MATERIALS, Issue 1 2005C. Picart Abstract Polyelectrolyte multilayers (PEMs) are now widely used for biomedical applications. In this work, we investigated the primary osteoblast adhesion properties of PEMs of poly(L -lysine) (PLL), poly(L -glutamic acid) (PGA), poly(alginic acid) (Palg), and poly(galacturonic acid) (Pgal). In order to compensate for the poor adhesion of the as-synthesized films, two kinds of film modifications were achieved: a purely physical modification by film crosslinking, and a chemical modification by grafting a arginine,glycine,aspartic acid (RGD) peptide to PGA. Crosslinking was performed using a water-soluble carbodiimide in combination with N -hydroxysulfosuccinimide (sulfo-NHS) to induce amide formation. This reaction was followed by Fourier-transform IR spectroscopy. For film functionalization, a 15-amino-acid peptide was grafted to PGA and deposited as the top layer of the film. PLL/PGA, PLL/Palg, and PLL/Pgal films were crosslinked or functionalized. The films were tested for both short-term adhesion properties and long-term proliferation of primary osteoblasts. Whereas the effect of film crosslinking on short-term adhesion was moderate, it was much more important for the RGD-functionalized films. On the other hand, the long-term proliferation was the same or even higher for the crosslinked films as compared with the functionalized films. This effect was particularly enhanced for the PLL/Palg and PLL/Pgal films. Finally, we functionalized PLL/PGA that had been crosslinked prior to PGA-RGD deposition. These architectures exhibited even higher short-term adhesion and proliferation. These results clearly show the important role of the physical properties of the films, besides their chemical properties, for the modulation of primary cell-adhesion behavior. [source] The effect of carbohydrate carbon sources on the production of constitutive and inducible laccases by Botryosphaeria sp.JOURNAL OF BASIC MICROBIOLOGY, Issue 5 2003Mário A. Alves da Cunha The influence of carbohydrates: glucose, fructose, galactose, galacturonic acid, xylose, lactose, sucrose, pectin and inulin, were evaluated as sole carbon source for the production of laccases by the ascomycete, Botryosphaeria sp. Veratryl alcohol, a laccase inducer, was added to culture media to study inducible laccase production on the same carbon sources. Inulinase and pectinase were also produced when Botryosphaeria sp. was grown on inulin, and galacturonic acid and pectin, respectively, and their levels were less in the presence of veratryl alcohol. Botryosphaeria sp. produced constitutive laccases on all carbon sources examined, and veratryl alcohol increased the laccase production on most of carbon sources studied except for inulin and galacturonic acid. Evidence is presented that Botryosphaeria sp. is also pectinolytic. [source] EFFECTS OF CO-IMMOBILIZATION OF PECTINASE AND AMYLASE ON ULTRAFILTRATION OF APPLE JUICE SIMULATEJOURNAL OF FOOD PROCESS ENGINEERING, Issue 6 2001MARÍA E. CARRÍN ABSTRACT In view of its possible application in apple juice clarification, the potential of co-immobilized pectinase/amylase by physical adsorption on a polysulfone ultrafiltration hollow fiber was examined. Solutions containing different concentrations of pectin and starch were used. The effect of various operational parameters on the production of reducing compounds, mainly galacturonic acid and maltose, was investigated. Results indicated that relative permeate flux, during ultrafiltration of starch-pectin solutions, was up to 35% higher when commercial pectinase and amylase were co-immobilized on a hollow fiber membrane. Although the concentration of reaction products increased up to 50% with the pectin concentration, the same was not verified when the starch content changed from 3.85 to 5.00 mg/mL. However, the reference permeate flux was improved when starch was added to substrate, independently of its concentration. Considering the size of an average starch granule, this increase in permeate flux was attributed to the removal of pectin gel by dragging. Permeate fluxes were comparable for both batch and permeate recycling operations. [source] Composition and properties of biologically active pectic polysaccharides from leek (Allium porrum)JOURNAL OF THE SCIENCE OF FOOD AND AGRICULTURE, Issue 12 2010Maria Kratchanova Abstract BACKGROUND: Leek (Allium porrum) is very commonly used vegetable in Bulgaria and is distinctive with high content of bioactive components1. Previously2 we obtained five crude pectic polysaccharides from leek through consecutive extraction. Some of them appeared to be good stimulators of the immune system. Schols and Voragen3 investigated the composition of modified hairy regions of pectic polysaccharides isolated from leek cell walls. Samuelson et al.4 identified the polysaccharide structures encountered in hairy regions as bioactive. The aim of this work was to study the isolation, composition and biological activities of pectic polysaccharides from leek. RESULTS: Two pectic polysaccharides from leek were isolated through consecutive water and acid extraction. The water extractable pectin had higher polyuronic content, higher protein content and lower neutral sugar content. It was found that next to galacturonic acid they also contain glucuronic acid in ratio 9:1 for the water- and 3:1 for the acid-extractable polysaccharide. The main neutral sugar was galactose. The water-extractable pectic polysaccharide had higher molecular weight (106 Da) and homogeneity. It was shown that the pectic polysaccharides from leek have considerable immunostimulating activities. CONCLUSION: Leek polysaccharides have relatively high galacturonic and glucuronic acid content and are distinguished with high biological activity. Copyright © 2010 Society of Chemical Industry [source] Nuclear magnetic resonance water relaxation time changes in bananas during ripening: a new mechanismJOURNAL OF THE SCIENCE OF FOOD AND AGRICULTURE, Issue 12 2010Fayene Zeferino Ribeiro Abstract BACKGROUND: Nuclear magnetic resonance studies of banana fragments during ripening show an increase on the water transverse relaxation time (T2) and a decrease in water self-diffusion coefficient (D). As T2 and D are normally directly correlated, we studied these two properties in intact bananas during ripening, in an attempt to rule out the effect of injury on the apparent discrepancies in the behavior of T2 and D. RESULTS: The results show that injury in bananas causes a decrease in T2 of the water in vacuoles (T2vac). They also show that T2vac increased and D decreased during ripening, ruling out the injury effect. To explain the apparent discrepancies, we propose a new hypothesis for the increase in T2 values, based on the reduction of Fe3+ ions to Fe2+ by galacturonic acid, produced by the hydrolysis of pectin and a decrease in internal oxygen concentration during ripening. CONCLUSION: As injury alters T2 values it is necessary to use intact bananas to study relaxation times during ripening. The novel interpretation for the increase in T2vac based on reduction of Fe+3 and O2 concentration is an alternative mechanism to that based on the hydrolysis of starch in amyloplasts. Copyright © 2010 Society of Chemical Industry [source] Characterisation of a haemagglutinin from Hokkaido red bean (Phaseolus vulgaris cv. Hokkaido red bean)JOURNAL OF THE SCIENCE OF FOOD AND AGRICULTURE, Issue 1 2010Jack H Wong Abstract BACKGROUND: A haemagglutinin was purified from Japanese Hokkaido red beans (Phaseolus vulgaris cv. Hokkaido red bean) with a procedure that included three chromatographic media. RESULTS: Haemagglutinating activity was adsorbed on DEAE cellulose, Affi-gel blue gel and Mono S. The pure haemagglutinin was a homodimer and each subunit was around 30 kDa in molecular mass. The haemagglutinating activity of this agglutinin could not be inhibited by a variety of simple sugars at 200 mmol L,1 concentration including ,- L -fucose, D(+)-galactose, D(+)-glucose, D(+)-glucosamine, D(,)galactosamine, galacturonic acid, (+)-lactose, D(+)-melibose, L(,)-mannose, D(+)-mannose, D -mannosamine, D(+)-raffinose, L -rhamnose, (+)-xylose and galacturonic acid. The haemagglutinating activity was fully retained at pH 4,11 and at 0,80 °C, but was completely lost at extreme pH values (0,2 and 13,14) and at very high temperatures (90 °C and 100 °C). The haemagglutinin exhibited a weak mitogenic activity toward mouse splenocytes, a stronger anti-proliferative activity than Con A toward HepG2 (human hepatoma) cells and inhibited >80% of HIV-1 reverse transcriptase inhibitory activity at 3.3 µmol L,1. It was devoid of anti-fungal activity. CONCLUSION: Hokkaido red bean haemagglutinin possesses a potent anti-proliferative effect on HepG2 cells. Copyright © 2009 Society of Chemical Industry [source] The RhaS activator controls the Erwinia chrysanthemi 3937 genes rhiN, rhiT and rhiE involved in rhamnogalacturonan catabolismMOLECULAR MICROBIOLOGY, Issue 5 2004Nicole 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] Isolation and characterization of the cell-surface polysaccharides of Porphyromonas gingivalis ATCC 53978MOLECULAR ORAL MICROBIOLOGY, Issue 3 2000S. I. Farquharson The cell-surface carbohydrates of Porphyromonas gingivalis strain ATCC 53978 were isolated and partially characterized. Three separate polysaccharides were found to be present: an extracellular polysaccharide, capsular polysaccharide and lipopolysaccharide. The capsular polysaccharide, which had peculiar, gel-like viscoelastic properties, was found to be comprised of mannuronic acid, glucuronic acid, galacturonic acid, galactose, and 2-acetamido-2-deoxy- d -glucose in relative molar ratios of 0.6:0.9:0.5:0.5:1.0, respectively. The extracellular polysaccharide was found to contain mannose, rhamnose, glucose, galactose, and 2-acetamido-2-deoxy- d -glucose in relative molar ratios of 13.5:1.4:1.0:2.0:1.0, respectively. The lipopolysaccharide was found to contain an O -antigen with a regular tetrasaccharide repeat unit comprised of 4-linked ,- l -rhamnopyranosyl, 6-linked ,- d -glucopyranosyl, 3-linked ,- d -galactopyranosyl, and 4-linked 2-acetamido-2-deoxy-,- d -glucopyranosyl residues in equimolar proportions. [source] | |||||||||||||