Structural features of an acidic polysaccharide from the mucin of Drosera binata

The polysaccharide from the mucin secreted by the leaves of Drosera binata is composed of l-arabinose, d-xylose, d-galactose, d-man     

Structural features of a polysaccharide from the mucin of water hyacinth

The mucin found in the nodal region of the weed, water hyacinth (Eichhornia crassipes), is a heteropolysaccharide composed of d-xylose, l-galactose and l-arabinose in the mol ratio of 1.3:1.2:1.0. Partial hydrolysis with acid gave four oligosaccharides which were characterized as: d-Xylp-(1 → 3)-l-Ara, l-Galp-(1 -→ 2)-l-Ara, d-Xylp-(1 → 3)-l-Galp-(1 → 2)-l-Ara, and d-Xylp-(1 → 2)-d-Xylp-(1 → 3)-l-Galp-(1 → 2)-l-Ara. These, together with the results of methylation analysis using GC and GC/MS and periodate oxidation, indicated that the trisaccharide repeating unit, → 4)-d-Xylp-(1 → 3)-l-Galp-(1 → 2)-l-Araf-(1 →, constitutes the backbone of the polysaccharide. Further, all the d-xylopyranosyl residues of the backbone are substituted at O-2 and, in addition, one out of seven such residues is also substituted at O-3; the substituents being l-Araf-(1 →, d-Xylp-(1 →, l-Galp-(1 →, d-Xylp-(1 → 3)-l-Araf-(1 →, residues.     

Structural characterisation of the pectic polysaccharide rhamnogalacturonan II using an acidic fingerprinting methodology

Rhamnogalacturonan II (RG-II) is a structurally complex cell wall pectic polysaccharide. Despite its complexity, both the structure of RG-II and its ability to dimerise via a borate diester are conserved in vascular plants suggesting that RG-II has a fundamental role in primary cell wall organisation and function. The selection and analysis of new mutants affected in RG-II formation represents a promising strategy to unravel these functions and to identify genes encoding enzymes involved in RG-II biosynthesis. In this paper, a novel fingerprinting strategy is described for the screening of RG-II mutants based on the mild acid hydrolysis of RG-II coupled to the analysis of the resulting fragments by mass spectrometry. This methodology was developed using RG-II fractions isolated from citrus pectins and then validated for RG-II isolated from the Arabidopsis mur1 mutant and irx10 irx10-like double mutant.     

Structural features of the sulphated polysaccharide from a green seaweed,Caulerpa taxifolia

A sulphated heteropolysaccharide was isolated from a green seaweed, Caulerpa taxifolia, by extraction with acid and purified via its copper complex. Methylation analysis of both the sulphated and desulphated polysaccharides revealed the presence of 1,4-linked xylose, 1,6-linked galactose, 1,4,6-linked mannose and non-reducing galactose end group units which are all devoid of sulphate groups. In addition 1,4-linked galactose units sulphated at C-3 are also present. Quantitative periodate oxidation showed a consumption of 1.30 and 1.60 moles of oxidant per anhydrosugar unit in the sulphated and desulphated polysaccharides respectively. The oxo-polysaccharides after reduction and hydrolysis revealed the presence of glycerol, erythritol and unoxidized galactose in the mol ratio 11.6:5.1:4.9 and 11.2:5.0:1.0 respectively, besides threitol (3.9 mol) in the desulphated polysaccharide.     

Structural features of a water soluble gum polysaccharide from Murraya paniculata fruits

A water soluble gum polysaccharide was isolated from Murraya paniculata fruits. Hydrolytic experiments, methylation analysis, periodate oxidation studies and NMR data revealed that the polysaccharide was extensively branched and it consisted of 1,3-, and 1,3,6-linked beta-D-galactopyranosyl units, terminal beta-D-galactopyranosyl units and terminal alpha-D-glucopyranosyl 1,4-beta-D-galactopyranosyl units. Small amounts of 4-O-methylglucuronic acid residues were also present.     

Structural features of the sulphated polysaccharide from a green seaweed, Spongomorpha indica.

A sulphated heteropolysaccharide, [alpha]D +59 degrees, was isolated from a green seaweed, Spongomorpha indica, by extraction with ammonium oxalate. The polymer is composed of arabinose, xylose, galactose and glucose in the ratio 8.9:1.0:12.0:1.0. Studies showed that the polysaccharide is a complex and multilinked polymer containing arabinose in both furanose and pyranose forms. The core of the polysaccharide is composed of 1,4-linked galactose units. The arabinofuranose units are present as non-reducing end units, as well as jointed through 1,3- and 1,2-linkages. The majority of the arabinopyranose units are joined through 1,4-linkages. Xylose is present as a branch terminating unit. Glucose is joined through 1,4-linkages. Both arabinose and galactose carry branches. Sulphate groups are present on some of the arabinose units at C-2 and on some of the galactose units at C-2 and C-3.     

Structural features of the sulphated polysaccharide from a green seaweed, Cladophora socialis.

A sulphated heteropolysaccharide, [alpha]27D + 59.9 degrees, has been isolated from a green seaweed, Cladophora socialis, by extraction with dilute acid and purified by fractional precipitation. The polymer is composed of galactose (58.3%), arabinose (31.8%), xylose (10.6%) and sulphate (16.9%). The results of methylation analysis, periodate oxidation and partial acid hydrolysis studies indicate that the polymer is a branched one and is composed of 1,3-linked galactose and 1,4-linked arabinose units. Xylose is present at the non-reducing end position of the branches. Both arabinose and galactose carry branches. Desulphation and subsequent analysis of the polymer show that some of the arabinose units carry sulphate groups at C-3 and some of the galactose units carry the sulphate groups at C-4 and some at C-4 and C-6 as well.     

Structural studies of an acidic polysaccharide from Ocimum basilicum seeds

An acidic polysaccharide isolated from the seeds of Ocimum basilicum by DEAE-cellulose fractionation was ～92% pure, having an associated glucan impurity (～8%). The polysaccharide is composed of d-xylose, l-arabinose, l-rhamnose, and d-galacturonic acid in the molar ratios 15:9:7:12, together with traces or galactose and glucose. Methylation analysis indicated that the polysaccharide contained a (1→4)-linked xylan backbone carrying branch-points at C-2 and C-3 of the xylosyl residues, and revealed the structural features of the side chains. Periodateoxidation and Smith-degradation studies support the results of methylation analysis.     

Effects of ingested fruiting bodies, submerged culture biomass, and acidic polysaccharide glucuronoxylomannan of Tremella mesenterica Retz.:Fr. on glycemic responses in normal and diabetic rats

Mushroom polysaccharides have been shown to regulate glucose metabolism. Using male Wistar rats injected with saline (normal rats), streptozotocin (STZ-NT rats), or streptozotocin plus nicotinamide (STZ+NT rats), we investigated the hypoglycemic activity of orally ingested fruiting bodies (FB), submerged culture biomass (CM), or the acidic polysaccharide glucuronoxylomannan (GXM) of Tremella mesenterica, an edible jelly mushroom. Our results demonstrated that FB ingestion significantly attenuated the elevated blood glucose levels in an oral glucose tolerance test (OGTT) in STZ-NT rats. However, in STZ+NT rats, FB, CM, and GXM ingestion significantly attenuated the increases in food and water intake, 2-h postprandial blood glucose concentrations, and blood glucose levels in OGTT. Moreover, FB and GXM ingestion significantly decreased serum concentration of fructosamine in STZ+NT rats. Our results indicated that T. mesenterica might be developed as a potential oral hypoglycemic agent or functional food for diabetic patients and for persons with high risk for diabetes mellitus.     

Structural features conserved in subclass of type II arabinogalactan

Arabinogalactan-proteins (AGPs) are extracellular proteoglycans, which are presumed to participate in the regulation of cell shape, thus contributing to the excellent mechanical properties of plants. AGPs consist of a hydroxyproline-rich core-protein and large arabinogalactan (AG) sugar chains, called type II AGs. These AGs have a β-1,3-galactan backbone and β-1,6-galactan side chains, to which other sugars are attached. The structure of type II AG differs depending on source plant, tissue, and age. Type II AGs obtained from woody plants in large quantity as represented by gum arabic and larch AG, here designated gum arabic-subclass, have a β-1,3;1,6-galactan structure in which the β-1,3-galactan backbone is highly substituted with short β-1,6-galactan side chains. On the other hand, it is unclear whether type II AGs found as the glycan part of AGPs from herbaceous plants, here designated AGP-subclass, also have conserved β-1,3:1,6-galactan structural features. In the present study we explore similarities of type II AG structures in the AGP-subclass. Type II AGs in fractions obtained from spinach, broccoli, bok choy, komatsuna, and cucumber were hydrolyzed into galactose and β-1,6-galactooligosaccharides by specific enzymes. Based on the proportion of these sugars, the substitution ratio of the β-1,3-galactan backbone was calculated as 46–58% in the five vegetables, which is consistently lower than what is seen in gum arabic and larch AG. Although most side chains were short, long chains such as β-1,6-galactohexaose chains were also observed in these vegetables. The results suggest a conserved β-1,3;1,6-galactan structure in the AGP-subclass that distinguishes it from the gum arabic-subclass.     

Structural studies of the capsular polysaccharide from Streptococcus pneumoniae type 5

The structure of the capsular polysaccharide (S5) elaborated by Streptococcus pneumoniae type 5 has been investigated by using n.m.r. spectroscopy, methylation analysis, and various specific degradations. It is concluded that the polysaccharide is composed of pentasaccharide repeating-units having the following structure: (Formula: see text) In this structure, L-PneNAc stands for 2-acetamido-2,6-dideoxy-L-talose (pneumosamine) and D-Sug for 2-acetamido-2,6-dideoxy-D-xylo-hexos-4-ulose. The latter sugar accounts for the lability of S5 towards alkali. N.m.r. spectra indicate heterogeneity in S5, most probably associated with the hexosyl-4-ulose residue.     

Structural characterization of oligosaccharides isolated from the pectic polysaccharide rhamnogalacturonan II

Rhamnogalacturonan II (RG-II) is a structurally complex pectic (d-galactosyl-uronic acid-rich) polysaccharide that is present in the primary (growing) cell-walls of higher plants. RG-II is composed of ∼60 glycosyl residues. The isolation and structural characterization of 23 oligosaccharide fragments of the residue of RG-II that remained after removal of hepta- and di-saccharides by partial hydrolysis with acid are reported. In order to obtain the oligosaccharide fragments characterized herein, the carboxyl groups of RG-II were dideuterio-reduced, and the carboxyl-reduced polysaccharide was per-O-methylated. The per-O-methylated polysaccharide was fragmented by partial hydrolysis with acid, producing partially O-methylated oligosaccharides. These derivatized oligosaccharides were reduced, to afford a mixture of partially O-methylated oligoglycosyl-alditols, which was then per-O-methylated. The structures of the resulting per-O-methylated oligoglycosylalditols were determined by chemical-ionization mass spectrometry, electron-impact mass spectrometry, fast-atom-bombardment mass spectrometry, ¹H-n.m.r. spectroscopy, and analysis of corresponding, partially O-acetylated, partially O-methylated alditols. Seventeen of the oligosaccharides isolated from RG-II were parts of a single heptasaccharide, namely.     

Structural studies on a polysaccharide from Shigella dysenteriae type 7

The polysaccharide obtained from the O-somatic antigen of Shigella dysenteriae type 7 (strain NCTC 519/66) contains d-glucose, d-galactose, and 2-acetamido-2-deoxy-d-glucose in the mole ratios of 2:1:1. From the results of methylation, periodate oxidation, graded hydrolysis, and deamination studies, the structure assigned to the repeating unit of the polysaccharide is as follows.

Oxidation studies with chromium trioxide revealed the nature of the anomeric linkages of some of the sugar residues in the polysaccharide.     

Structural studies of an acidic polysaccharide from the mucin secreted by Drosera capensis

The polysaccharide of the mucin secreted by the leaves of Drosera capensis is composed of l-arabinose, d-xylose, d-galactose, d-mannose, and d-glucuronic acid in the molar ratio of 3.6:1.0:4.9:8.4:8.2. For structural elucidation, methylation analysis using g.l.c. and g.l.c.-m.s. was performed on the native, the carboxyl-reduced, and the degraded polysaccharides. Partial hydrolysis, periodate oxidation, chromium trioxide oxidation, and uronic acid degradation were also performed on the native and carboxyl-reduced polysaccharides. Partial hydrolysis of the native and carboxyl-reduced polysaccharides gave various oligosaccharides that were characterized and suggest a structure containing a d-glucurono-d-mannan backbone having a repeating unit → 4)-β-d-GlcpA-(1 → 2)-α-d-Manp-(1 →. l-Arabinose and d-xylose are present as nonreducing furanosyl and pyranosyl end-groups, respectively, both attached to O-3 of d-glucuronic acid residues of the backbone. d-Galactose is present as non-reducing pyranosyl end-group linked to O-3 of d-mannose residues.     

Structural features of a sulphated,fucose-containing polysaccharide from the brown seaweed dictyota dichotoma

A sulphated heteropolysaccharide (～15% of the acid-extractable material) isolated from the brown alga Dictyota dichotoma contains residues of D-glucuronic acid, D-galactose, D-mannose, D-xylose, and L-fucose¹. Partial hydrolysis of the polysaccharide with acid gave one neutral and two acidic oligosaccharides. The behaviour towards periodate of the polysaccharide before and after partial hydrolysis, alkali-treatment, and methanolysis has been studied. Evidence is thereby provided that the polysaccharide is partially sulphated and composed of (1→4)-linked residues of D-glucuronic acid, D-galactose, D-mannose, and D-xylose, and (1→2)-linked L-fucose.     

Structural studies of the capsular polysaccharide from Klebsiella type 1

The structure of the capsular polysaccharide from Klebsiella type 1, which is composed of D-glucose, D-glucuronic acid, L-fucose, and pyruvic acid (1:1:1:1), has been investigated. Methylation analysis, n.m.r. spectroscopy, graded hydrolysis, and periodate-oxidation studies were the principal methods used. These studies demonstrated that the polysaccharide consists of the following trisaccharide repeating-unit: