Characterisation of cell-wall polysaccharides from mandarin segment membranes
Coll-Almela, L. ; Saura-Lopez, D. ; Laencina-Sanchez, J. ; Schols, H.A. ; Voragen, A.G.J. ; Ros-García, J.M. - \ 2015
Food Chemistry 175 (2015). - ISSN 0308-8146 - p. 36 - 42.
hairy ramified regions - cross-flow filtration - pectolytic enzyme - citrus-fruit - pectins - degradation - extraction - skin - rhamnogalacturonase - populations
In an attempt to develop a process of enzymatic peeling of mandarin segments suitable for use on an industrial scale, the cell wall fraction of the segment membrane of Satsuma mandarin fruits was extracted to obtain a chelating agent-soluble pectin fraction (ChSS), a dilute sodium hydroxide-soluble pectin fraction (DASS), a 1 M sodium hydroxide-soluble hemicellulose fraction (1MASS), a 4 M sodium hydroxide-soluble hemicellulose fraction (4MASS) and a cellulose-rich residue (3.1, 0.9, 0.4, 0.7 and 1.6% w/w of fresh membrane, respectively). The ChSS pectin consisted mainly of galacturonic acid followed by arabinose and galactose. The DASS fraction contained less galacturonic acid and more neutral sugars than ChSS. Eighty-nine percent of the galacturonic acid present in the segment membranes was recovered in the above two pectin fractions. The two hemicellulosic fractions consisted of two different molecular weight populations, which also differed in their sugar composition. Arabinose, xylose, mannose, galactose and glucose were the main sugar constituents of these hemicellulose fractions. In addition to an (arabino)xylan and a xyloglucan, the presence of an arabinogalactan is suggested by the sugar composition of both hemicelluloses. The pectin fractions were also characterised by their degradability by the pectic enzymes polygalacturonase, pectinmethylesterase and rhamnogalacturonan hydrolase. However the degree of degradation of the pectin fractions by enzymes differed, and the amount of the polymeric materials resistant to further degradation and the oligomeric products also differed. Using pectic enzymes it is possible to obtain peeled mandarin segments ready to eat or for canning.
Effects on interfacial properties and cell adhesion of surface modification by pectic hairy regions
Morra, M. ; Cassinelli, C. ; Cascardo, G. ; Nagel, M.D. ; Volpe, C. Della; Siboni, S. ; Maniglio, D. ; Brugnara, M. ; Ceccone, G. ; Schols, H.A. ; Ulvskov, P. - \ 2004
Biomacromolecules 5 (2004)6. - ISSN 1525-7797 - p. 2094 - 2104.
polysaccharide-coated surfaces - atomic-force microscopy - ramified regions - heparin - polystyrene - binding - wall - rhamnogalacturonase - antithrombin - architecture
Polystyrene Petri dishes, aminated by a plasma deposition process, were surface modified by the covalent linking of two different enzymatically modified hairy regions (HRs) from pectin containing, for example, rhamnogalacturonan-I and xylogalacturonan structural elements. The two polysaccharide preparations share the same structural elements of apple pectin, but the relative amounts and lengths of the neutral side chains present differ. Surface analysis by X-ray photoelectron spectroscopy, contact angle measurement, and atomic force microscope (AFM) force-separation curves was used to characterize the effects on surface chemistry and interfacial forces of the surface modification process. Cell adhesion experiments using continuous L-929 fibroblasts and primary aortic smooth muscle cells were performed to evaluate the effect of the polysaccharide nature on cell adhesion. Results show that immobilization of the HR affects the interfacial field of forces and the cell behavior: "equilibrium" contact angles, obtained by a recently introduced vibrational approach, decrease after HR immobilization reaching a value close to 20. AFM force-separation curves show a more extended (or softer) interface in the case of the HR bearing longer side chains. Accordingly, depending on the HR preparation, cells shifted from spread morphology and adhesion behavior quantitatively comparable to that observed on conventional tissue culture polystyrene to rounded morphology and significantly lower adhesion. These data show that engineering of plant pectins can be a valuable tool to prepare novel and finely tuned polysaccharides having different chemico-physical and biological properties, to be used in the surface modification of medical devices and materials.
Degradation of differently substituted xylogalacturonans by endoxylogalacturonan hydrolase and endopolygalacturonases.
Beldman, G. ; Vincken, J.P. ; Schols, H.A. ; Meeuwsen, P.J.A. ; Herweijer, M.A. ; Voragen, A.G.J. - \ 2003
Biocatalysis and Biotransformation 21 (2003)4/5. - ISSN 1024-2422 - p. 189 - 198.
hairy ramified regions - aspergillus-niger - pectins - enzyme - rhamnogalacturonase - polysaccharides - chromatography - oligomers - sugars
A method was developed to make xylogalacturonans (XGAs) with different degrees of xylosylation from gum tragacanth (XGA-25, XGA-29, XGA-35 and XGA-47), using alkali treatment at 4degreesC and acid treatment at 100degreesC. Ester linkages as well as fucose and arabinose substituents could selectively be removed by this procedure. Galactosyl- and xylosyl-linkages appeared to be more stable, while some backbone degradation of the galacturonan took place upon prolonged acid treatment. Using XGA-35, endoxylogalacturonan hydrolase (XGH) from Aspergillus tubingensis , expressed in Kluyveromyces lactis , was characterised with respect to kinetic parameters, temperature and pH effects. XGA-25 and XGA-47 were degraded with endopolygalacturonases (PGs) from Aspergillus niger (PG1, PG2), from A. tubingensis (PG-arf), from Kluyveromyces fragilis (PG-kluyv) and XGH from A. tubingensis . The activity of the different PGs decreased with increasing degrees of xylosylation. However, for each PG a different tolerance for the presence of side chains was observed. PG-arf and PG1 were hindered most by xylosyl branching, whereas XGH appeared to have a requirement for xylosylation and was almost not active towards polygalacturonic acid. The degradability of xylogalacturonans by XGH increased with higher degrees of xylosylation. Typically, a highly substituted xylogalacturonan from pea was almost resistant to XGH treatment. XGH produces a distinctive set of oligosaccharides from XGA, which is different from the hydrolysis products of PG action. Saponified modified hairy regions from apple (MHR-S), containing xylogalacturonan, were partially degraded by XGH. A combination of XGH and rhamnogalacturonan hydrolase was able to fully degrade the high molecular weight fraction of MHR-S. The two enzymes acted additively, no synergy being observed.