Staff Publications

Staff Publications

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    'Staff publications' is the digital repository of Wageningen University & Research

    'Staff publications' contains references to publications authored by Wageningen University staff from 1976 onward.

    Publications authored by the staff of the Research Institutes are available from 1995 onwards.

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Culinary-medicinal mushrooms: must action be taken?
Griensven, L.J.L.D. van - \ 2009
International Journal of Medicinal Mushrooms 11 (2009)3. - ISSN 1521-9437 - p. 281 - 286.
agaricus-bisporus - fungal metabolites - cancer-therapy - extracts - immunochemotherapy - polysaccharides
In the Western world, the mushroom industry suffers from overproduction. Expectations are stronger than reality, and as a result, production is too high and prices are too low. Because bulk production has taken the lead, which not only happens in the West, overproduction occurs regularly. Low pricing influences the quality concept of consumers and hence their appreciation of mushrooms. This cannot continue without doing great harm to the socioeconomic structure of the industry. Therefore, measures have to be taken to introduce mushrooms as a true health food in the Western world. This may form a first step in the acceptance of mushroom extracts and mushroom-derived compounds as medicine in the prevention and cure of disease. The present review discusses the acceptance of mushrooms as health food and medicine and suggests pathways for necessary action
Inhibition of LPS-induced proinflammatory responses of J774.2 macrophages by immobilized enzymatically tailored pectins
Gallet, M. ; Vayssade, M. ; Morra, M. ; Verhoef, R.P. ; Perrone, S. ; Cascardo, G. ; Vigneron, P. ; Schols, H.A. ; Nagel, M.D. - \ 2009
Acta Biomaterialia 5 (2009). - ISSN 1742-7061 - p. 2618 - 2622.
hairy ramified regions - glinus-oppositifolius - rhamnogalacturonan-i - cell - polysaccharides - adhesion - activation - polymer - plant - vitro
The surface of an implant device can be modified by immobilizing biological molecules on it to improve its integration into the host tissue. We have previously demonstrated that enzymatically tailored plant pectins are promising nanocoatings for biomaterials. This study investigates whether a coating of modified hairy region (rhamnogalacturonan-I) from apple pectin (MHR-a) which has anti-adhesive properties can inhibit the generation of inflammatory mediators by lipopolysaccharide (LPS)-activated macrophages. For that purpose, J774.2 murine macrophages were cultured for 24 h on MHR-a-coated Petri dishes and tissue culture polystyrene controls, with and without LPS. Cell morphology, cell growth, nitrite and TNF-a secretion were studied. The results indicate that MHR-a coating inhibits the LPS-induced activation of macrophages.
Release and characterization of single side chains of white cabbage pectin and their complement-fixing activity
Westereng, B. ; Coenen, G.J. ; Michaelsen, T.E. ; Voragen, A.G.J. ; Samuelsen, A.B. ; Schols, H.A. ; Knutsen, S.H. - \ 2009
Molecular Nutrition & Food Research 53 (2009). - ISSN 1613-4125 - p. 780 - 789.
plantago-major l - structural features - biological-activity - cell-walls - polysaccharides - arabinogalactan - residues - acid - xylogalacturonan - homogalacturonan
A mixture of single side chains from white cabbage pectin were obtained by anion exchange chromatography after applying mild chemical conditions promoting -elimination. These pectin fragments were characterized by their molecular weight distribution, sugar composition, 13C-NMR, and MALDI-TOF-MS analysis. These analyses revealed that the large oligosaccharides released by -eliminative treatment were composed of -1,5 linked arabinosyl residues with 2- and 3-linked -arabinosyl side chains, and, or -1,4 linked galactosyl side chains. Fractions were tested for complement-fixing activity in order to determine their interaction with the complement system. These results strongly indicated that there was a minimal unit size responsible for the complement-fixing activity. Neutral pectin fragments (8 kDa) obtained from -elimination were inactive in the complement system, although they contained a sugar composition previously shown to be highly active. Larger pectin fragments (17 kDa) retained some activity, but much lower than polymers containing rhamnogalacturonan type 1 (RGI) structures isolated from the same source. This implied that structural elements containing multiple side chains is necessary for efficient complement-fixing activity.
Okra pectin contains an unusual substitution of its rhamnosyl residues with acetyl and alpha-linked galactosyl groups
Sengkhamparn, N. ; Bakx, E.J. ; Verhoef, R.P. ; Schols, H.A. ; Sajjaanantakul, T. ; Voragen, A.G.J. - \ 2009
Carbohydrate Research : an international journal 344 (2009)14. - ISSN 0008-6215 - p. 1842 - 1851.
hairy ramified regions - fat ingredient substitute - rhamnogalacturonan oligomers - structural-characterization - galacturonic acid - oligosaccharides - polysaccharides - degradation - substances - products
The okra plant, Abelmoschus esculentus (L.) Moench, a native plant from Africa, is now cultivated in many other areas such as Asia, Africa, Middle East, and the southern states of the USA. Okra pods are used as vegetables and as traditional medicines. Sequential extraction showed that the Hot Buffer Soluble Solids (HBSS) extract of okra consists of highly branched rhamnogalacturonan (RG) I containing high levels of acetyl groups and short galactose side chains. In contrast, the CHelating agent Soluble Solids (CHSS) extract contained pectin with less RG I regions and slightly longer galactose side chains. Both pectic populations were incubated with homogeneous and well characterized rhamnogalacturonan hydrolase (RGH), endo-polygalacturonase (PG), and endo-galactanase (endo-Gal), monitoring both high and low molecular weight fragments. RGH is able to degrade saponified HBSS and, to some extent, also non-saponified HBSS, while PG and endo-Gal are hardly able to degrade either HBSS or saponified HBSS. In contrast, PG is successful in degrading CHSS, while RGH and endo-Gal are hardly able to degrade the CHSS structure. These results point to a much higher homogalacturonan (HG) ratio for CHSS when compared to HBSS. In addition, the CHSS contained slightly longer galactan side chains within its RG I region than HBSS. Matrix-assisted laser desorption ionization-time of flight mass spectrometry indicated the presence of acetylated RG oligomers in the HBSS and CHSS enzyme digests and electron spray ionization-ion trap-mass spectrum showed that not only galacturonosyl residues but also rhamnosyl residues in RG I oligomers were O-acetylated. NMR spectroscopy showed that all rhamnose residues in a 20 kDa HBSS population were O-acetylated at position O-3. Surprisingly, the NMR data also showed that terminal a-linked galactosyl groups were present as neutral side chain substituents. Taken together, these results demonstrate that okra contained RG I structures which have not been reported before for pectic RG I.
Modulating in vitro bone cell and macrophage behavior by immobilized enzymatically tailored pectins
Bussy, C. ; Verhoef, R.P. ; Haeger, A. ; Morra, M. ; Duval, J.L. ; Vigneron, P. ; Bensoussan, A. ; Velzenberger, E. ; Cascardo, G. ; Cassinelli, C. ; Schols, H.A. ; Knox, J.P. ; Nagel, M.D. - \ 2008
Journal of Biomedical Materials Research Part A 86a (2008)3. - ISSN 1549-3296 - p. 597 - 606.
hairy ramified regions - osteoblast adhesion - extracellular-matrix - surface modification - synthetic peptides - rhamnogalacturonan - growth - polysaccharides - biomaterials - activation
Previous work has reported the results of a multidisciplinary effort producing a proof-of-concept on the use of pectic polysaccharides in the surface modification of medical devices. This study was designed to learn more about the capability of engineered rhamnogalacturonan-I (RG-I) fractions of apple pectin to control bone cell and macrophage behavior. Thermanox® or polystyrene Petri dishes were surface modified with two different modified hairy regions (MHRs) obtained by different enzymatic liquefaction processes of apples differing in relative amounts and lengths of their neutral side chains: (long-haired) MHR- and (short-haired) MHR-B. Bone explants from 14-day-old chick embryos were cultured for 14 days on both pectic substrata. MHR-B promoted cell migration and differentiation, MHR- did not. On MHR-, J774.2 macrophages grew well, their percentage in G1 phase was decreased and in S phase increased, and they did not secrete either proinflammatory-cytokines or nitrites. Contrasting results were gained from macrophages on MHR-B, except for nitrite secretion. Thus, we conclude that coatings from tailored pectins show different biological activities in vitro and are potential innovative candidates for improving the biocompatibility of medical devices in various applications. © 2007 Wiley Periodicals, Inc. J Biomed Mater Res, 2008
Effect of wheat cultivar and enzyme addition to broiler chicken diets on nutrient digestibility, performance, and apparent metabolizable energy content.
Gutierrez del Alamo Oms, A. ; Verstegen, M.W.A. ; Hartog, L.A. den; Villamide, M.J. - \ 2008
Poultry Science 87 (2008)4. - ISSN 0032-5791 - p. 759 - 767.
chemical-composition - supplementation - polysaccharides - variety - poultry - starch - barley - assay
A total of 5,000 one-day-old male broiler chickens were assigned to 8 different treatments in a 4 x 2 factorial design. Four wheat cultivars (Amiro, Guadalupe, Isengrain, and Horzal) and 2 levels (0 or 1 kg/t of feed) of an enzyme cocktail (Avizyme 1300, xylanase, 2,500 U/kg and protease, 800 U/kg) were used. Nutritionally complete mash diets contained 65 and 70% of the test wheat for the starter and grower period, respectively. Test wheats were used in diets for broilers, and growth performance and AME contents were measured. Broiler performance was measured in 4,800 broilers allocated to floor pens with 75 birds each and fed from 1 to 42 d of age. Digestibilities and AME contents of diets were measured in 200 broilers from 6 to 27 d of age individually allocated to battery cages. Chromic oxide (Cr2O3) at an inclusion rate of 0.5% in the diet was used as an indigestible marker. Apparent metabolizable energy was corrected by zero N balance to obtain AMEn. Wheat cultivar strongly influenced animal performance during the starter period (1 to 21 d of age). During the grower period (21 to 42 d of age), only BW and daily feed intake were influenced by wheat cultivar. Differences in daily feed intake were associated with differences in AMEn intake during the starter period, but not during the grower period. Nutrient digestibility was higher with the use of enzyme. Animal performance was not affected (i.e., wheat cultivar differences were not eliminated by using enzymes). During the grower period, significant interactions were detected with regard to nutrient digestibility and AMEn. Differences in AMEn content of wheat could not be explained by digestible starch.
Bifidobacterium glycoside hydrolases and (potential) prebiotics
Broek, L.A.M. van den; Voragen, A.G.J. - \ 2008
Innovative Food Science and Emerging Technologies 9 (2008)4. - ISSN 1466-8564 - p. 401 - 407.
adolescentis dsm20083 - in-vitro - probiotics - oligosaccharides - arabinoxylan - longum - fermentation - bacteria - cloning - polysaccharides
Carbohydrates occur in food as natural constituents or are added as ingredients. In the last decade a number of novel dietary carbohydrates have been introduced as ingredients for food applications, responding to the growing awareness among consumers of the link between health and diet. One important group is formed by the non-digestible oligosaccharides (NDOs) which may function as prebiotics. In many studies it has been shown that prebiotics in the diet positively influence the human intestinal microbiota. It is envisaged that this will balance the microbial composition in the gastrointestinal tract in favor of health promoting genera such as Bifidobacterium and Lactobacillus. In this review we will focus on the degradation of (potential) prebiotics, derived from plant (poly)saccharides, by bifidobacterial glycoside hydrolases. In addition the possibilities to use or produce new classes of NDOs using the most important glycoside hydrolases from Bifidobacterium sp. will be discussed.
Intrahepatic CD8+ lymphocyte trapping during tolerance induction using mushroom derived formulations: A possible role for liver in tolerance induction
Shuvy, M. ; Hershcovici, T. ; Lull-Noguera, C. ; Wichers, H.J. - \ 2008
World Journal of Gastroenterology 14 (2008)24. - ISSN 1007-9327 - p. 3872 - 3878.
inflammatory-bowel-disease - lentinus-edodes mycelia - t-cells - nkt cells - experimental colitis - medicinal mushrooms - immune-reactions - polysaccharides - antitumor - immunomodulation
AIM: To determine the immunomodulatory effect of Shiitake (a mushroom extract), we tested its effect on liver-mediated immune regulation in a model of immune-mediated colitis. METHODS: Four groups of mice were studied. Colitis was induced by intracolonic instillation of TNBS in groups A and B. Groups A and C were treated daily with Shiitake extract, while groups B and D received bovine serum albumin. Mice were evaluated for development of macroscopic and microscopic. The immune effects of Shiitake were determined by FACS analysis of intra-hepatic and intrasplenic lymphocytes and IFN-¿ ELISPOT assay. RESULTS: Administration of Shiitake resulted in by an increased intrasplenic/intrahepatic CD4/CD8 lymphocyte ratio. These effects were accompanied by a 17% increase in the number of intrahepatic natural killer T (NKT) cells. A similar effect was observed when Shiitake was administered to animals without disease induction. CONCLUSION: Shiitake extract affected livermediated immune regulation by altering the NKT lymphocyte distribution and increasing intrahepatic CD8+ T lymphocyte trapping, thereby leading to alleviation of immune-mediated colitis marked alleviation of colitis, manifested by significant improvement in the macroscopic and microscopic scores, and by reduction in IFN-¿-producing colonies in group A, compared to group B mice (1.5 pfu/mL vs 3.7 pfu/mL, respectively). This beneficial effect was associated with a significant increase in the intrahepatic CD8+ lymphocyte trapping, demonstrated
Effect of enzyme extracts isolated from white-rot fungi on chemical composition and in vitro digestibility of wheat straw
Rodrigues, M.A.M. ; Pinto, P. ; Bezerra, R.M.F. ; Dias, A.A. ; Guedes, C.M. ; Cone, J.W. - \ 2008
Animal Feed Science and Technology 141 (2008)3-4. - ISSN 0377-8401 - p. 326 - 338.
volatile fatty-acids - rumen microorganisms - manganese peroxidase - trametes-versicolor - lignin degradation - phenolic-acids - rice straw - fermentation - fiber - polysaccharides
A series of in vitro experiments were completed to evaluate the potential of enzyme extracts, obtained from the white-rot fungi Trametes versicolor (TV1, TV2), Bjerkandera adusta (BA) and Fomes fomentarius (FF), to increase degradation of cell wall components of wheat straw. The studies were conducted as a completely randomized design and analysed using one-way ANOVA. Enzyme activities of the extracts, previously obtained from a liquid culture medium, were characterized in terms of laccase and peroxidase for ligninolytic activity. Carboxymethyl cellulase (CMCase) and avicell digesting cellulase (Avicelase) were used for cellulolytic enzyme assays. Wheat straw samples were incubated with enzyme extracts in a citrate buffer (pH 5.0) in a forced air oven at 25 °C for 6 days. In vitro NDF digestibility (IVNDFD), and the rate and extent of NDF fermentation, without and after incubation with the white-rot enzyme extracts, were determined using a gravimetric microbiological method and a gas production technique, respectively. Results from cell wall chemical composition showed that TV2 and BA enzyme extracts decreased NDF concentration (P
Texture of food gels explained by combining structure and large deformation properties
Berg, L. van den - \ 2008
Wageningen University. Promotor(en): Tiny van Boekel; Erik van der Linden, co-promotor(en): F. van de Velde; Ton van Vliet. - S.l. : S.n. - ISBN 9789085049432 - 193
gels - wei-eiwit - polysacchariden - textuur - structuur - mechanische eigenschappen - reologische eigenschappen - confocale microscopie - gels - whey protein - polysaccharides - texture - structure - mechanical properties - rheological properties - confocal microscopy
Low Molecular Weight Melanoidins in Coffee Brew
Bekedam, E.K. ; Roos, E. ; Schols, H.A. ; Boekel, M.A.J.S. van; Smit, G. - \ 2008
Journal of Agricultural and Food Chemistry 56 (2008)11. - ISSN 0021-8561 - p. 4060 - 4067.
maillard reaction-products - chemical-characterization - antioxidant activity - colored compounds - roasted coffee - arabica beans - model systems - polysaccharides - xylose - lysine
Analysis of low molecular weight (LMw) coffee brew melanoidins is challenging due to the presence of many non-melanoidin components that complicate analysis. This study focused on the isolation of LMw coffee brew melanoidins by separation of melanoidins from non-melanoidin components that are present in LMw coffee brew material. LMw coffee fractions differing in polarity were obtained by reversed-phase solid phase extraction and their melanoidin, sugar, nitrogen, caffeine, trigonelline, 5-caffeoylquinic acid, quinic acid, caffeic acid, and phenolic groups contents were determined. The sugar composition, the charge properties, and the absorbance at various wavelengths were investigated as well. The majority of the LMw melanoidins were found to have an apolar character, whereas most non-melanoidins have a polar character. The three isolated melanoidin-rich fractions represented 56% of the LMw coffee melanoidins and were free from non-melanoidin components. Spectroscopic analysis revealed that the melanoidins isolated showed similar features as high molecular weight coffee melanoidins. All three melanoidin fractions contained ~3% nitrogen, indicating the presence of incorporated amino acids or proteins. Surprisingly, glucose was the main sugar present in these melanoidins, and it was reasoned that sucrose is the most likely source for this glucose within the melanoidin structure. It was also found that LMw melanoidins exposed a negative charge, and this negative charge was inversely proportional to the apolar character of the melanoidins. Phenolic group levels as high as 47% were found, which could be explained by the incorporation of chlorogenic acids in these melanoidins
Kinetics of Acid Hydrolysis of Water-Soluble Spruce O-Acetyl Galactoglucomannans
Xu, C. ; Pranovich, A. ; Vahasalo, L. ; Hemming, J. ; Holmbom, B. ; Schols, H.A. ; Willfor, S. - \ 2008
Journal of Agricultural and Food Chemistry 56 (2008)7. - ISSN 0021-8561 - p. 2429 - 2435.
molecular-weight changes - thermomechanical pulp - enzymatic-hydrolysis - degradation - chitosan - depolymerization - polysaccharides - products - polymers
Water-soluble O-acetyl galactoglucomannan (GGM) is a softwood-derived polysaccharide, which can be extracted on an industrial scale from wood or mechanical pulping waters and now is available in kilogram scale for research and development of value-added products. To develop applications of GGM, information is needed on its stability in acidic conditions. The kinetics of acid hydrolysis of GGM was studied at temperatures up to 90 °C in the pH range of 1¿3. Molar mass and molar mass distribution were determined using size exclusion chromatography with multiangle laser light scattering and refractive index detection. The molar mass of GGM decreased considerably with treatment time at temperatures above 70 °C and pH below 2. The molar mass distribution broadened with hydrolysis time. A first-order kinetic model was found to match the acid hydrolysis. The reaction rate constants at various pH values and temperatures were calculated on the basis of the first-order kinetic model. Furthermore, the activation energy, E, was obtained from the Arrhenius plot. The activation energy E was 150 kJ mol¿1 for acid hydrolysis of spruce GGM. The apparent rate constant during acid hydrolysis increased by a factor of 10 with a decrease in pH by 1 unit, regardless of temperature. In addition, gas chromatography and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry were applied to study the released GGM monomers and oligomers. Keywords: Kinetics; acid hydrolysis; galactoglucomannans; oligosaccharides; stability.
High-throughput screening of monoclonal antibodies against plant cell wall glycans by hierarchical clustering of their carbohydrate microarray binding profiles
Moller, I. ; Marcus, S.E. ; Haeger, A. ; Verhertbruggen, Y. ; Verhoef, R.P. ; Schols, H.A. ; Ulvskov, P. ; Mikkelsen, J.D. ; Knox, J.P. ; Willats, W.G.T. - \ 2008
Glycoconjugate Journal 25 (2008)1. - ISSN 0282-0080 - p. 37 - 48.
oligosaccharide microarrays - arabinogalactan-proteins - glycomics - pectin - polysaccharides - generation - epitope - carrot - homogalacturonan - glycoproteins
Antibody-producing hybridoma cell lines were created following immunisation with a crude extract of cell wall polymers from the plant Arabidopsis thaliana. In order to rapidly screen the specificities of individual monoclonal antibodies (mAbs), their binding to microarrays containing 50 cell wall glycans immobilized on nitrocellulose was assessed. Hierarchical clustering of microarray binding profiles from newly produced mAbs, together with the profiles for mAbs with previously defined specificities allowed the rapid assignments of mAb binding to antigen classes. mAb specificities were further investigated using subsequent immunochemical and biochemical analyses and two novel mAbs are described in detail. mAb LM13 binds to an arabinanase-sensitive pectic epitope and mAb LM14, binds to an epitope occurring on arabinogalactan-proteins. Both mAbs display novel patterns of recognition of cell walls in plant materials. Keywords Carbohydrate microarrays - Plant cell walls - Monoclonal antibodies - Hierarchical clustering
Structure of mixed Beta-lactoglobulin/pectin adsorbed layers at air/water interfaces; a spectroscopy study
Ganzevles, R.A. ; Fokkink, R.G. ; Vliet, T. van; Cohen Stuart, M.A. ; Jongh, H.H.J. de - \ 2008
Journal of Colloid and Interface Science 317 (2008)1. - ISSN 0021-9797 - p. 137 - 147.
air-water-interface - o/w emulsions - neutron reflection - protein adsorption - pectin - casein - films - polysaccharides - complexes - membranes
Based on earlier reported surface rheological behaviour two factors appeared to be important for the functional behaviour of mixed protein/polysaccharide adsorbed layers at air/water interfaces: (1) protein/polysaccharide mixing ratio and (2) formation history of the layers. In this study complexes of ß-lactoglobulin (positively charged at pH 4.5) and low methoxyl pectin (negatively charged) were formed at two mixing ratios, resulting in negatively charged and nearly neutral complexes. Neutron reflection showed that adsorption of negative complexes leads to more diffuse layers at the air/water interface than adsorption of neutral complexes. Besides (simultaneous) adsorption of protein/polysaccharide complexes, a mixed layer can also be formed by adsorption of (protein/)polysaccharide (complexes) to a pre-formed protein layer (sequential adsorption). Despite similar bulk concentrations, adsorbed layer density profiles of simultaneously and sequentially formed layers were persistently different, as illustrated by neutron reflection analysis. Time resolved fluorescence anisotropy showed that the mobility of protein molecules at an air/water interface is hampered by the presence of pectin. This hampered mobility of protein through a complex layer could account for differences observed in density profiles of simultaneously and sequentially formed layers. These insights substantiated the previously proposed organisations of the different adsorbed layers based on surface rheological data.
Effects of dietary water holding capacity and level of fermentable organic matter on digesta passage in various parts of the digestive tract in growing pigs
Leeuwen, P. van; Jansman, A.J.M. - \ 2007
Livestock Science 109 (2007)1-3. - ISSN 1871-1413 - p. 77 - 80.
gastric-emptying rate - fiber - polysaccharides - absorption - starch - flow
The effect diet composition on digesta passage over three sections of the gastro-intestinal tract (GIT) was studied in growing pigs. A control diet (C diet) and three diets differing in the contents of non-starch polysaccharides (NSP) and water holding capacity (WHC) were fed. Results showed a mean transit time (MTT) over the whole GIT over all diets of 75 h. NSP significantly (P <0.05) decreased MTT over the total GIT and through the large intestine. In contrast, NSP tended to increase the MTT of the stomach contents (P <0.10). The effects of WHC were limited to tendencies for a decrease of the MTT in the large intestine (P <0.10) and an increase of the MTT in the small intestine (P <0.10).
Regulation of pentose catabolic pathway genes of Aspergillus niger
Groot, M.J.L. de; Dool, C. van den; Wosten, H.A.B. ; Levisson, M. ; vanKuyk, P.A. ; Ruijter, G.J.G. ; Vries, R.P. de - \ 2007
Food Technology and Biotechnology 45 (2007)2. - ISSN 1330-9862 - p. 134 - 138.
transcriptional activator xlnr - d-xylose - l-arabinose - alpha-glucuronidase - degrading enzymes - kinase gene - expression - nidulans - polysaccharides - degradation
The aim of this study was to obtain a better understanding of the pentose catabolism in Aspergillus niger and the regulatory systems that affect it. To this end, we have cloned and characterised the genes encoding A. niger L-arabitol dehydrogenase (ladA) and xylitol dehydrogenase (xdhA), and compared the regulation of these genes to other genes of the pentose catabolic pathway. This demonstrated that activation of the pathway depends on two transcriptional regulators, the xylanolytic activator (XlnR) and an unidentified L-arabinose specific regulator (AraR). These two regulators affect those genes of the pentose catabolic pathway that are related to catabolic conversion of their corresponding inducers (D-xylose and L-arabinose, respectively).
Xylogalacturonan exists in cell walls from various tissues of Arabidopsis thaliana
Zandleven, J.S. ; Sorensen, S. ; Harbolt, J. ; Beldman, G. ; Schols, H.A. ; Scheller, H.V. ; Voragen, A.G.J. - \ 2007
Phytochemistry 68 (2007)8. - ISSN 0031-9422 - p. 1219 - 1226.
enzymatic degradation - polysaccharides - hydrolase - purification - pectin - leaves - apple
Evidence is presented for the presence of xylogalacturonan (XGA) in Arabidopsis thaliana. This evidence was obtained by extraction of pectin from the seeds, root, stem, young leaves and mature leaves of A. thaliana, followed by treatment of these pectin extracts with xylogalacturonan hydrolase (XGH). Upon enzymatic treatment, XGA oligosaccharides were primarily produced from pectin extracts obtained from the young and mature leaves and to a lesser extent from those originating from the stem of A. thaliana. The oligosaccharide GalA3Xyl was predominantly formed from these pectin extracts. No XGA oligosaccharides were detected in digests of pectin extracts from the seeds and roots. A low number of XGA oligosaccharides was obtained from pectins of A. thaliana. This indicates a uniform distribution of xylose in XGA from A. thaliana. The predominant production of GalA3Xyl, as well as the release of linear GalA oligosaccharides pointed to a lower degree of xylose substitution in XGA from A. thaliana than in XGA from apple and potato. The estimated amount of XGA accounted for approximately 2.5%, 7% and 6% (w/w) of the total carbohydrate in the pectin fraction of the stem, young leaves and mature leaves, respectively.
Molecular details of ovalbumin-pectin complexes at the air/water interface: a spectroscopic study.
Kudryashova, E.V. ; Visser, A.J.W.G. ; Hoek, A. van; Jongh, H.H.J. de - \ 2007
Langmuir 23 (2007)15. - ISSN 0743-7463 - p. 7942 - 7950.
air-water-interface - resolved fluorescence spectroscopy - alpha-chymotrypsin - polyelectrolyte complexes - protein adsorption - liquid interfaces - globular-proteins - kinetics - polysaccharides - stabilization
To stabilize air-water interfaces, as in foams, the adsorption of surface-active components is a prerequisite. An approach to controlling the surface activity of proteins is noncovalent complex formation with a polyelectrolyte in the bulk phase. The molecular properties of egg white ovalbumin in a complex with pectin in the bulk solution and at air/water interfaces were studied using drop tensiometry (ADT) and time-resolved fluorescence anisotropy techniques. The complex formation of ovalbumin with pectin in the bulk resulted in the formation of a compact structure with a different spatial arrangement depending on the protein/pectin ratio. Complex formation did not provide an altered protein structure, whereas the conformational stability was slightly increased in the complex. In excess pectin, an overall condensed complex structure is formed, whereas at limited pectin concentrations the structure of the complex is more "segmental". The characteristics of these structures did not depend on pH in the 7.0 to 4.5 regime. Interaction with pectin in the bulk solution resulted in a significantly slower adsorption of the protein to the air/water interface. The limited mobility of the protein at the interface was found for both ovalbumin and ovalbumin-pectin complexes. From both the rotational dynamics and total fluorescence properties of the protein in the absence and presence of pectin, it was suggested that the complex does not dissociate at the interface. Ovalbumin in the complex retains its initial "aqueous" microenvironment at the interface, whereas in the absence of pectin the microenvironment of the protein changed to a more nonpolar one. This work illustrates a more general property of polyelectrolytes, namely, the ability to retain a protein in its microenvironment. Insight into this property provides a new tool for better control of the surface activity of complex biopolymer systems.
Promiscuous, non-catalytic, tandem carbohydrate-binding modules modulate the cell-wall structure and development of transgenic tobacco (Nicotiana tabacum) plants
Olawole, O. ; Jacobsen, E. ; Timmers, J.F.P. ; Gilbert, H.J. ; Blake, W. ; Knox, J.P. ; Visser, R.G.F. ; Vincken, J.P. - \ 2007
Journal of Plant Research 120 (2007)5. - ISSN 0918-9440 - p. 605 - 617.
arabidopsis-thaliana - bacterial cellulose - gene-expression - growth - xyloglucan - polysaccharides - protein - endo-1,4-beta-glucanase - recognition - elongation
We have compared heterologous expression of two types of carbohydrate binding module (CBM) in tobacco cell walls. These are the promiscuous CBM29 modules (a tandem CBM29-1-2 and its single derivative CBM29-2), derived from a non-catalytic protein1, NCP1, of the Piromyces equi cellulase/hemicellulase complex, and the less promiscuous tandem CBM2b-1-2 from the Cellulomonas fimi xylanase 11A. CBM-labelling studies revealed that CBM29-1-2 binds indiscriminately to every tissue of the wild-type tobacco stem whereas binding of CBM2b-1-2 was restricted to vascular tissue. The promiscuous CBM29-1-2 had much more pronounced effects on transgenic tobacco plants than the less promiscuous CBM2b-1-2. Reduced stem elongation and prolonged juvenility, resulting in delayed flower development, were observed in transformants expressing CBM29-1-2 whereas such growth phenotypes were not observed for CBM2b-1-2 plants. Histological examination and electron microscopy revealed layers of collapsed cortical cells in the stems of CBM29-1-2 plants whereas cellular deformation in the stem cortical cells of CBM2b-1-2 transformants was less severe. Altered cell expansion was also observed in most parts of the CBM29-1-2 stem whereas for the CBM2b-1-2 stem this was observed in the xylem cells only. The cellulose content of the transgenic plants was not altered. These results support the hypothesis that CBMs can modify cell wall structure leading to modulation of wall loosening and plant growth.
Arabinogalactan Proteins Are Incorporated in Negatively Charged Coffee Brew Melanoidins
Bekedam, E.K. ; Laat, M.P.F.C. de; Schols, H.A. ; Boekel, M.A.J.S. van; Smit, G. - \ 2007
Journal of Agricultural and Food Chemistry 55 (2007)3. - ISSN 0021-8561 - p. 761 - 768.
arabica beans - maillard reaction - espresso coffee - green - model - food - polysaccharides - electrophoresis - substances - components
The charge properties of melanoidins in high molecular weight (HMw) coffee brew fractions, isolated by diafiltration and membrane dialysis, were studied. Ion exchange chromatography experiments with the HMw fractions showed that coffee brew melanoidins were negatively charged whereas these molecules did not expose any positive charge at the pH of coffee brew. Fractions with different ionic charges were isolated and subsequently characterized by means of the specific extinction coefficient (Kmix 405nm), sugar composition, phenolic group content, nitrogen content, and the arabinogalactan protein (AGP) specific Yariv gel-diffusion assay. The isolated fractions were different in composition and AGP was found to be present in one of the HMw fractions. The AGP accounted for 6% of the coffee brew dry matter and had a moderate negative charge, probably caused by the presence of uronic acids. As the fraction that precipitated with Yariv was brown (Kmix 405nm = 1.2), compared to a white color in the green bean, it was concluded that these AGPs had undergone Maillard reaction resulting in an AGP-melanoidin complex. The presence of mannose (presumably from galactomannan) indicates the incorporation of galactomannans in the AGP-melanoidin complex. As the uronic acid content in the more negatively charged melanoidin-rich, AGP-poor HMw fractions decreased, it was hypothesized that acidic groups are formed or incorporated during melanoidin formation.
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