Malcolm A. O'Neill

Structure of the acidic extracellular gelling polysaccharide produced by Pseudomonas elodea

Abstract The gelling polysaccharide secreted by the bacterium Pseudomonas elodea contains l -rhamnose, d -glucose, and d -glucuronic acid in the molar ratios 1:2:1. Methylation analysis of native and carboxyl-reduced polysaccharide indicated (1→4)-Rha p , (1→3)-Glc p , (1→4)-Glc p , and (1→4)-Glc p A to be present in the ratios 1:1:1:1. Graded acid hydrolysis gave a series of acidic oligosaccharides that were isolated by ion-exchange chromatography and fractionated by gel-filtration. The purified oligosaccharides were analysed and characterised as their methylated alditol derivatives by e.i.-m.s. and c.i.-m.s., and also examined by fast-atom-bombardment (f.a.b.)-m.s. The tetrasaccharide repeating-unit 1 , excluding acetyl groups, is proposed.

Isolation and partial characterisation of a xyloglucan from the cell walls of Phaseolus coccineus

Abstract Cell-wall material from Phaseolus coccineus was fractionated by successive extraction with aqueous inorganic solvents. From the 4 m KOH-soluble fraction, a polymer composed of l -arabinose (4.2%), l -fucose (6.0%), d -galactose (9.3%), d -xylose (34.1%), and d -glucose (46.4%) was isolated and purified by ion-exchange and cellulose column chromatography; the product was homogeneous by moving-boundary electrophoresis and ultracentrifugation. The S20,wo and Dobs were 2.92 S and 1.7 × 10−7, respectively, and the molecular weight was ∼110,000. Methylation analysis suggested a (1→4)-linked glucan backbone with ∼3 out of 4 glucosyl residues substituted through O-6 with xylose or oligosaccharides terminating in galactose, fucose, and arabinose. Limited acetolysis gave several di- and tri-saccharide derivatives of which four [ d -Galp-(1→2)- d -Xylp, d -Glcp-(1→4)- d -Glcp, l -Fucp-(1→2)- d -Galp-(1→2)- d -Xylp, and d -Glcp-(1→4)- d -Glcp-(1→4)- d -Glcp] were tentatively identified. Specific glycosidases were used to determine the configuration of the glycosidic linkages. The backbone was shown to be a (1→4)-β- d -glucan and the l -fucosyl groups were α. Neither α- nor β- d -galactosidase removed d -galactose. The structure of the xyloglucan is discussed in relation to other cell-wall polymers, especially cellulose.

Structure of the extracellular polysaccharide produced by the bacterium Alcaligenes (ATCC 31555) species

Abstract The extracellular anionic polysaccharide produced by the bacterium Alcaligenes (ATCC 31555) contains l -mannose, l -rhamnose, d -glucose, and d -glucuronic acid in the molar ratios 1.0:4.5:3.1:2.3. Analysis of the methylated and methylated, carboxyl-reduced polysaccharide indicated terminal non-reducing rhamnose and mannose, (1→4)-linked rhamnose, (1→3)- and (1→3,1→4)-linked glucose, and (1→4)-linked glucuronic acid to be present in the ratios 1.0:0.8:2.1:2.2:2.0:2.2. Partial acid hydrolysis and base-catalysed β-elimination gave a series of oligosaccharides that were isolated as their alkylated alditol derivatives by reverse-phase h.p.l.c. and characterised by f.a.b.-m.s., e.i.-m.s., and 1H-n.m.r. spectroscopy. The repeating unit 1, excluding O-acyl groups, is proposed.

Methylation analysis of cell-wall material from parenchymatous tissues of phaseolus vulgaris and phaseolus coccineus

Abstract Cell-wall material (CWM) from parenchymatous tissues of pods of dwarf french and runner beans was prepared by sequentially extracting the wet ball-milled tissues with 1% aqueous sodium deoxycholate, phenol-acetic acid-water, and 90% aqueous dimethyl sulphoxide. The overall monosaccharide compositions of the preparations were similar, and each contained small but significant amounts of hydroxyprolinerich glycoproteins. Methylation analysis of the CWM revealed the following main glycosidic linkages in descending order of concentration: 4-linked galacturonic acid, 4-linked glucose, 4-linked galactose, 5-linked arabinose, 2-linked rhamnose, and 4-linked xylose. The major branch-points were those through C-6 of glucose, C-3 of arabinose, and C-4 of rhamnose. Arabinose, xylose, and galactose constituted the non-reducing end-groups. The general structural features of the CWM are discussed.

Structure of the extracellular gelling polysaccharide produced by Enterobacter (NCIB 11870) species

The gelling polysaccharide produced by a species of Enterobacter (NCIB 11870) contains L-fucose, D-glucose, and D-glucuronic acid in the ratios 1:2:1. Analysis of the methylated and methylated, carboxyl-reduced polysaccharide revealed terminal non-reducing glucose, (1----3)-linked fucose, (1----3,1----4)-linked glucose, and (1----4)-linked glucuronic acid in the ratios 1:1:1.2:0.8. From the results of Smith degradation of the polysaccharide and spectroscopic studies of the acidic tetra- and octa-saccharides produced by bacteriophage-induced enzymic depolymerization of the polysaccharide, the following tetrasaccharide repeating-unit is proposed. (Formula: see text). This repeating-unit is identical to that of the capsular polysaccharide produced by Klebsiella aerogenes serotype K54 except for the absence of O-acetyl groups. The effects of the O-acetyl groups on the secondary structure and rheological properties of these polysaccharides are discussed.

Structural analysis of the xyloglucan from Phaseolus coccineus cell-walls using cellulase-derived oligosaccharides

Abstract Oligosaccharides, obtained by digestion of a xyloglucan from the cell walls of Phaseolus coccineus with cellulase, have been isolated by gel filtration. Oligosaccharides containing 2–6 residues accounted for ∼57% of the hydrolysate, with larger oligosaccharides (d.p. ∼10) and partially degraded xyloglucan accounting for ∼32% of the polymer. The major glycosidic linkages were determined by methylation analysis. Methylated penta- and hexa-saccharide alditols were isolated by reverse-phase h.p.l.c. and characterised by e.i.-m.s. and f.a.b.-m.s. Methylated derivatives of the di-, tri-, and tetra-saccharide alditols were examined by g.l.c.-m.s. in the e.i. and c.i. modes. A structure based on these results is proposed.

Methylation analysis of cell wall glycoproteins and glycopeptides from Chlamydomonas reinhardii

Abstract Cell wall glycoproteins from Chlamydomonas reinhardii and the glycopeptides produced by the action of thermolysin were subjected to standard methylation analysis. GC-MS of the methylated alditol acetates revealed short oligosaccharides some of which show branching. O-glycosidically linked galactofuranosyl residues are present. The asymmetric distribution of the major O-glycosidic linkages is also reported.

Structural features of the mucilage from the stem pith of kiwifruit (actinidia deliciosa): part I, structure of the inner core

Abstract The mucilage found in the stem pith of Actinidia deliciosa contains d -glucuronic acid, d -mannose, l -fucose, l -arabinose, and d -galactose in the molar ratios 1.0:1.5:2.0:4.0. The native, carboxyl-reduced, and partially acid-hydrolysed polysaccharides were subjected to methylation analysis. Partial acid hydrolysis of the methylated, carboxyl-reduced glucuronomannan core produced a series of methylated oligosaccharides which, as their alditol derivatives, were isolated by reverse-phase h.p.l.c. and characterised by e.i.- and f.a.b.-m.s. The data suggest that the polysaccharide contains a →4)-β- d -Glc p A-(1→2)-α- d -Man p -(1→ backbone with most of the d -mannosyl and d -glucosyluronic acid residues substituted through positions 3 with oligosaccharides containing l -arabinose, α- l -fucose, and β- d -galactose.

Structural features of the mucilage from the stem pith of kiwifruit (acitinidia deliciosa_: part II, structure of the neutral oligosaccharides

Abstract Graded acid hydrolysis of the mucilage from the stem pith of Actinidia deliciosa gave a series of neutral oligosaccharides that were fractionated by gel filtration. The methylated alditol derivatives were isolated by reverse-phase h.p.l.c. and characterised by f.a.b.-m.s., e.i.-m.s., and g.l.c.—m.s. of the methylated alditol acetates. The results suggest the glucuronomannan core of the mucilage is substituted with oligosaccharides composed of (1→3)-linked β- d -galactose residues that are partially substituted through positions 2 and 6 with Araf, Arap, Fucp, and Galp. A tentative structure for the mucilage is proposed.