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  • 1
    Electronic Resource
    Electronic Resource
    Xyloglucan oligosaccharides with at least two α-d-xylose residues act as acceptor substrates for xyloglucan endotransglycosylase and promote the depolymerisation of xyloglucan (1993)
    Oxford, UK : Blackwell Publishing Ltd
    Physiologia plantarum 88 (1993), S. 0 
    Details
    ISSN: 1399-3054
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: A xyloglucan-derived pentasaccharide. Xyl2-Glc3, was shown by viscometry to promote the depolymerisation of xyloglucan by enzyme extracts from bean (Phaseolus vulgaris L. cv. Canadian Wonder) leaves and pea (Pisum sativum L. cv. Alaska) stems. Xyl2-Glc3 was also shown by a radiochemical assay to act as an acceptor substrate for xyloglucan endotransglycosylase activity (XET: EC 2.4.1.—) present in the same extracts. In both these assays, a heptasaccharide (Xyl3-Glc4) was more effective than Xyl2-Glc3 whereas two isomeric tetrasaccharides (Xyl1-Glc3) were essentially ineffective. The agreement in the structural requirements of the two assays suggests that they share a common basis; we therefore propose that the oligosaccharide-sensitive enzyme that depolymerises xyloglucan is XET rather than cellulase (EC 3.2.1.4). In the viscometric assay, the penta- and heptasaccharides would, according to our interpretation, compete with high molecular weight xyloglucan molecules as acceptor substrates for XET, leading to a decrease in the weight-average molecular weight of the xyloglucan and, therefore, to a decrease in viscosity.Our results indicate that oligosaccharides have to possess two α-d-xylose residues in order to act as acceptor substrates for XET. The non-reducing end of a high-molecular weight xyloglucan can also act as an acceptor substrate. Therefore, it is likely that exo-hydrolysis by α-d-xylosidase would destroy the ability of a polysaccharide to act as an acceptor, even though α-d-xylosidase may remove only a single xylose residue from each polysaccharide molecule.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1399-3054.1993.tb01767.x
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  • 2
    Electronic Resource
    Electronic Resource
    An unambiguous nomenclature for xyloglucan-derived oligosaccharides (1993)
    Oxford, UK : Blackwell Publishing Ltd
    Physiologia plantarum 89 (1993), S. 0 
    Details
    ISSN: 1399-3054
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: A revised system of abbreviated names is proposed for xyloglucan-derived oligosaccharides. Each (1→4)-linked β-d-glucosyl residue (and the reducing terminal d-glucose moiety) of the backbone is given a one-letter code according to its substituents. The name of the oligosaccharide consists of these code letters listed in sequence from non-reducing to reducing terminus of the backbone.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1399-3054.1993.tb01778.x
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  • 3
    Electronic Resource
    Electronic Resource
    Implication of persimmon fruit hemicellulose metabolism in the softening process. Importance of xyloglucan endotransglycosylase (1994)
    Oxford, UK : Blackwell Publishing Ltd
    Physiologia plantarum 91 (1994), S. 0 
    Details
    ISSN: 1399-3054
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Hemicellulosic polysaccharides from persimmon fruit (Diospyros kaki L.) pericarp were extracted from depectinated cell walls with 0.5, 1 and 4 M KOH at different stages of development: (I) maximal growth corresponding to the first sigmoidal growth phase; (II) cessation of growth corresponding to the lag between the first and the second sigmoidal phases; (III) maximal growth corresponding to the second sigmoidal phase; and (IV) cessation of growth when the fruit had reached its maximum size and the change in colour (green to red) had taken place. During fruit development the amount of total hemicelluloses per unit dry mass cell wall decreased twofold. Xyloglucan was present in the three hemicellulosic fractions, and also decreased with fruit age, although its amount relative to other hemicelluloses increased. The amount of xyloglucan was especially high in the hemicelluloses extracted with 4 M KOH, representing more than 50% at stages III and IV. The average molecular mass of xyloglucan increased from stage I through stage II (0.5 M hemicellulosic fraction) or through stage III (I and 4 M hemicellulosic fractions) and decreased after that. The xyloglucan endotransglycosylase (XET: EC 2.4.1.-) activity was measured as the incorporation of [3H]XXXGol (reduced xyloglucan heptasaccharide labelled at position 1 of the glucitol moiety) into partially purified persimmon fruit xyloglucan. XET specific activity increased greatly between stages I and II. The importance of this enzyme during fruit ripening is discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1399-3054.1994.tb00415.x
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  • 4
    Electronic Resource
    Electronic Resource
    Xylogliicae- and cello-oligosaccharides: Antagonists of the growth-promoting effect of H+ (1990)
    Oxford, UK : Blackwell Publishing Ltd
    Physiologia plantarum 80 (1990), S. 0 
    Details
    ISSN: 1399-3054
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Xyloglucan-oligosaccharides and cello-oligosaccharides, both of which are potential products of the action of cellulase on plant cell wail polysaccharides, inhibited acid-induced elongation in pea (Pisum sativum L. cv. Alaska) stem segments. Xyloglucan-derived nonasaccharide (XG9; Glc4-Xyl3)Gal-Fuc) and decasaccharide (XG10; Glc4-Xyl3-Gal2-Fue) inhibited acid-induced growth at 1.0 and 0.1 nM, respectively, whereas the heptasaccharide (XG7; Glc4-Xyl3) and octasaccharide (XG8; Glc4-Xyl3-Gal)2 which lack L-fucose, did not. XG9 at 1 nM inhibited acid-induced growth as effectively as it inhibits auxin-induced elongation. This suggests that XG9's effect as an inhibitor of auxin action is not mediated by a suppresion of H+-efflux, but rather that XG9 blocks some step that is common to the action of both auxin and H+ on growth. Cello-oligosaccharides (degree of polymerisation 4–7) also inhibited acid-induced growth at 10 nM; these are therefore a new class of possible oligosaccha-rin. The inhibitory effect of xyloglucan- and cellooligosaccharides on acid-induced growth was rapidly reversed by washing.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1399-3054.1990.tb04382.x
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  • 5
    Electronic Resource
    Electronic Resource
    Cellulases, hemicelluloses and auxin-stimulated growth: a possible relationship (1989)
    Oxford, UK : Blackwell Publishing Ltd
    Physiologia plantarum 75 (1989), S. 0 
    Details
    ISSN: 1399-3054
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: The plant growth promoter, auxin, may loosen the primary cell wall by increasing the activity of extracellular cellulases – a group of enzymes that cleave hemicellulose chains in the walls of both monocotyledons and dicotyledons. Evidence is reviewed that suggests that these hemicellulose chains tether adjacent microfibrils, and that by cleaving such chains the cellulases facilitate cell expansion. On the basis of this structural arrangement a mechanism for elastic and plastic wall extension is proposed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1399-3054.1989.tb05620.x
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  • 6
    Electronic Resource
    Electronic Resource
    Intracellular feruloylation of pectic polysaccharides (1987)
    Springer
    Planta 171 (1987), S. 205-211 
    Details
    ISSN: 1432-2048
    Keywords: Cell wall ; Ferulic acid ; Pectic arabinogalactan ; Polysaccharide ; Secretion (polysaccharide) ; Spinacia (cell wall)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The pectic polysaccharides of spinach cell walls carry feruloyl groups on arabinose and galactose residues. The following experiments were designed to discover whether the arabinose residues are feruloylated intra-or extracellularly. Cultured spinach cells started to incorporate exogenous [3H]arabinose into polymers at a linear rate after a lag period of approx. 3–4 min, although radioactive polysaccharides and extensin did not start to appear outside the plasmalemma until after an approx. 25-min lag. In the same cells, polysaccharide-bound feruloyl-[3H]arabinose units starded to accumulate radioactivity at a linear rate after a lag period of approx. 4–5 min. Therefore, arabinose residues of polysaccharides began to be feruloylated while still intracellular. The rate of formation of polysaccharide-bound feruloyl-[3H]arabinose units did not appreciably increase after 25 min, showing that any additional extracellular feruloylation of the polysaccharide was relatively slow. This conclusion was supported by two different types of pulse-chase experiments, one of which was designed to detect feruloylation of polysaccharides up to 6 d after synthesis.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00391095
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  • 7
    Electronic Resource
    Electronic Resource
    The relationship between xyloglucan endotransglycosylase and in-vitro cell wall extension in cucumber hypocotyls (1993)
    Springer
    Planta 190 (1993), S. 327-331 
    Details
    ISSN: 1432-2048
    Keywords: Cell wall (expansion, enzymes) ; Cucumis (cell wall expansion) ; Enzyme (cell wall) ; Protein (cell wall extension inducing) ; Xyloglucan endotransglycosylase
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract It has been proposed that cell wall loosening during plant cell growth may be mediated by the endotransglycosylation of load-bearing polymers, specifically of xyloglucans, within the cell wall. A xyloglucan endotransglycosylase (XET) with such activity has recently been identified in several plant species. Two cell wall proteins capable of inducing the extension of plant cell walls have also recently been identified in cucumber hypocotyls. In this report we examine three questions: (1) Does XET induce the extension of isolated cell walls? (2) Do the extension-inducing proteins possess XET activity? (3) Is the activity of the extension-inducing proteins modulated by a xyloglucan nonasaccharide (Glc4-Xyl3-Gal2)? We found that the soluble proteins from growing cucumber (cucumis sativum L.) hypocotyls contained high XET activity but did not induce wall extension. Highly purified wall-protein fractions from the same tissue had high extension-inducing activity but little or no XET activity. The XET activity was higher at pH 5.5 than at pH 4.5, while extension activity showed the opposite sensitivity to pH. Reconstituted wall extension was unaffected by the presence of a xyloglucan nonasaccharide (Glc4-Xyl3-Gal2), an oligosaccharide previously shown to accelerate growth in pea stems and hypothesized to facilitate growth through an effect on XET-induced cell wall loosening. We conclude that XET activity alone is neither sufficient nor necessary for extension of isolated walls from cucumber hypocotyls.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00196961
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  • 8
    Electronic Resource
    Electronic Resource
    Inhibition of auxin-stimulated growth of pea stem segments by a specific nonasaccharide of xyloglucan (1988)
    Springer
    Planta 175 (1988), S. 412-416 
    Details
    ISSN: 1432-2048
    Keywords: Anti-auxin ; Auxin ; ‘Oligosaccharin’ ; Pisum (growth inhibition) ; Rosa ; Xyloglucan
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Hemicellulose extracted from cell walls of suspension-cultured rose (Rosa “Paul's Scarlet”) cells was digested with cellulase from Trichoderma viride. The quantitatively major oligosaccharide products, a nonasaccharide and a heptasaccharide derived from xyloglucan, were purified by gel permeation chromatography. The nonasaccharide was found to inhibit the 2,4-dichlorophenoxy-acetic-acid-induced elongation of etiolated pea (Pisum sativum) stem segments. This confirms an earlier report (York et al., 1984, Plant Physiol. 75, 295–297). The inhibition of elongation by the nonasaccharide showed a maximum at around 10-9M with higher and lower concentrations being less effective. The heptasaccharide did not significantly inhibit elongation at 10-7–10-10M and also did not affect the inhibition caused by the nonasaccharide when co-incubated with the latter.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00396348
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  • 9
    Electronic Resource
    Electronic Resource
    Transport, degradation and cell wall-integration of XXFGol, a growth-regulating nonasaccharide of xyloglucan, in pea stems (1997)
    Springer
    Planta 204 (1997), S. 78-85 
    Details
    ISSN: 1432-2048
    Keywords: Key words: Cell wall signalling ; Endotransglycosylase action ; Oligosaccharin ; Pisum stem (cell expansion) ; Xylem (translocation) ; Xyloglucan oligosaccharide
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract. When [glucitol-3H]XXFGol (a NaB3H4-reduced xyloglucan nonasaccharide) was applied to excised shoots of pea (Pisum sativum L. cv. Progress) at the base of the epicotyl, it inhibited growth in the elongation zone, 4–5 cm distal. Experiments were conducted to discover whether such 3H-oligosaccharides are translocated intact over this distance, or whether an intercellular second messenger would have to be postulated. After 24 h, 3H from [glucitol-3H]XXFGol and [glucitol-3H]XXXGol showed U-shaped distributions, with most 3H at the base and apex of the stem. Radioactivity from [fucosyl-3H]XXFG and [xylosyl-3H]XXFG also moved acropetally, but did not concentrate at the apex, possibly owing to removal from the transpiration stream of fucose and xylose formed by partial hydrolysis of XXFG en route. When 10−7 M [glucitol-3H]XXFGol was supplied, about 14 fmol ·  seedling–1 of apparently intact [3H]XXFGol was extractable from the elongation zone after 24 h. Larger amounts of degradation products were extractable (including free [3H]glucitol) and some wall-bound 3H-hemicellulose was present (presumably formed by the oligosaccharides acting as acceptor substrates for transglycosylation). We conclude that biologically active oligosaccharides of xyloglucan can move through the stem acropetally and that they are maintained at low steady-state concentrations by both hydrolysis and transglycosylation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004250050232
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  • 10
    Electronic Resource
    Electronic Resource
    Evidence for covalent linkage between xyloglucan and acidic pectins in suspension-cultured rose cells (2000)
    Springer
    Planta 211 (2000), S. 275-286 
    Details
    ISSN: 1432-2048
    Keywords: Key words: Homogalacturonan ; Pectin ; Rhamnogalacturonan ; Rosa (cell wall) ; Wall model ; Xyloglucan
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract.  Neutral xyloglucan was purified from the cell walls of suspension-cultured rose (Rosa sp. `Paul's Scarlet') cells by alkali extraction, ethanol precipitation and anion-exchange chromatography on `Q-Sepharose FastFlow'. The procedure recovered 70% of the total xyloglucan at about 95% purity in the neutral fraction. The remaining 30% of the xyloglucan was anionic, as demonstrated both by anion-exchange chromatography at pH 4.7 and by high-voltage electrophoresis at pH 6.5. Alkali did not cause neutral xyloglucan to become anionic, indicating that the anionic nature of the rose xyloglucan was not an artefact of the extraction procedure. Pre-incubation of neutral [3H]xyloglucan with any of ten non-radioactive acidic polysaccharides did not cause the radioactive material to become anionic as judged by electrophoresis, indicating that stable complexes between neutral xyloglucan and acidic polysaccharides were not readily formed in vitro. The anionic xyloglucan did not lose its charge in the presence of 8 M urea or after a second treatment with NaOH, indicating that its anionic nature was not due to hydrogen-bonding of xyloglucan to an acidic polymer. Proteinase did not affect the anionic xyloglucan, indicating that it was not associated with an acidic protein. Cellulase converted the anionic xyloglucan to the expected neutral nonasaccharide and heptasaccharide, indicating that the repeat-units of the xyloglucan did not contain acidic residues. Endo-polygalacturonase converted about 40% of the anionic xyloglucan to neutral material. Arabinanase and galactanase also converted appreciable proportions of the anionic xyloglucan to neutral material. These results show that about 30% of the xyloglucan in the cell walls of suspension-cultured rose cells exists in covalently-linked complexes with acidic pectins.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004250000287
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