Arabinose Residues Research Articles

Alkaline Hydrogen Peroxide Extraction of Wheat Bran Non-starch Polysaccharides

An extraction method based on the use of dilute alkaline solutions of hydrogen peroxide removing the lignin present in lignocellulosic materials (Gould, J. M. Biotechnology and Bioengineering 26 (1984) 46–52), was studied for the extraction of non-starch polysaccharides (NSP) from wheat bran. The influence of extraction temperature and time, hydrogen peroxide (H2O2) concentration and percentage of bran in the alkaline hydrogen peroxide solution on the extraction yields of non-cellulosic glucose, arabinose and xylose residues were investigated. Extraction for 4 h at 60 °C with an alkaline (pH 11.5) H2O2-solution (2·0%) and 2·0% wheat bran in the extractant yielded an alkaline extract containing 77% of the wheat bran total arabinose content, 65% of the total xylose content and 86% of the total non-cellulosic glucose content.

Structural features of the polysaccharide gum from Acacia glomerosa

Acacia glomerosa, Benth. (Vulgares Series) exudates a clear gum which produces gels easily. The physico-chemical data and sugar composition are very close to gum arabic from Acacia senegal, except that A. glomerosa gum contains a high nitrogen content. A series of degraded products was prepared by acid hydrolysis and Smith-degradation. The characterization of the degraded products by partial hydrolysis, sugar composition and by the application of uni- and bidimensional spectroscopy led to know interesting structural features of the polysaccharide isolated from A. glomerosa gum. This polysaccharide, as that from A. senegal gum, consists of 1,3-β- d-galactopyranosyl backbone. There are side-chains of 1,3-β- d-galactopyranosyl oligosaccharides attached to position six of the galactan main chain. Arabinose (furanosyl and pyranosyl) residues may be up to four units long because it was necessary to prepare four polysaccharides to remove them from the gum structure. Uronic acid residues were difficult to remove as has been observed in other Acacia gums.

Structural analyses of two arabinose containing oligosaccharides derived from olive fruit xyloglucan: XXSG and XLSG

Xyloglucan oligosaccharides were prepared by endo-(1→4)-β- d-glucanase digestion of alkali-extractable xyloglucan from olive fruit and purified by a combination of gel-permeation (Bio-Gel P-2) chromatography and high-performance anion-exchange chromatography. The two most abundant oligosaccharides were converted to the corresponding oligoglycosyl alditols by borohydride reduction and structurally characterised by NMR spectroscopy and post-source decay (PSD) fragment analysis of matrix-assisted laserinduced desorption/ionisation time-of-flight (MALDI-TOF) mass spectra. The results revealed that olive fruit xyloglucan is mainly built from two novel oligosaccharides: XXSG and XLSG. The structure of the oligosaccharides confirmed the presence of a specific xyloglucan in olive fruit with α- l-Ara f-(1→2)-α- d-Xyl p sidechains as was suggested previously. The presence of such sidechains is a common feature of xyloglucans with an XXGG core produced by solanaceous plants but has not been demonstrated for other dicotyledonous plants, which have in general an XXXG core. Direct treatment of cell wall material from olive fruit with pectin degrading enzymes in combination with endo-(1→4)-β- d-glucanase revealed that some of the arabinose residues of the oligosaccharides XXSG and XLSG are substituted with either 1 or 2 O-acetyl groups.

Involvement of terminal-arabinose and -galactose pectic compounds in mealiness of apple fruit during storage

Abstract Among eight apple cultivars (Malus domestica Borkh) held at 0 or 20°C for 4 or 8 weeks, mealiness was highest in ‘Starking Delicious’ (83%) and lowest in ‘Golden Delicious’ (0%) after 20°C for 8 weeks. In ‘Starking Delicious’ and ‘Golden Delicious’ fruit, total uronic acid contents [amount of water (WSP)+hexametaphosphate (HMP)+HCl soluble (HCP) pectic fractions] of the alcohol insoluble solids (AIS) of flesh hardly changed during storage at 20°C, although the ratio of uronic acid in WSP to total uronic acid increased during storage. Total (WSP+HMP+HCP) pentose contents in AIS decreased in most cultivars during storage, and the decrease was greatest in the fruit stored at 20°C. In ‘Starking Delicious’ fruit, the ratio of pentose in WSP to total pentose increased during storage at 20°C. Among pentoses, arabinose (Ara) content in the fruit stored at 20°C decreased more than in the fruit stored at 0°C. The linkages of the arabinose residue in each fraction were mainly T (terminal)-Ara, 5-Ara and 3,5-Ara, determined by methylation analysis. The ratio of T-Ara and 3,5-Ara to total arabinose linkage decreased both in HMP and HCP. The decrease in T-Ara and 3,5-Ara was higher in ‘Starking Delicious’ fruit compared with that in ‘Golden Delicious’ fruit in storage at 20°C. The linkages of the galactose residues in each fraction identified were mainly T-Gal, 3,6-Gal, 2,4-Gal and 6-Gal. The ratio of T-Gal to total galactose linkage increased both in HMP and HCP. The increase in T-Gal was higher in ‘Starking Delicious’ fruit than in ‘Golden Delicious’ fruit in storage at 20°C. The possible effect on mealiness of the release of T-Ara and increase of T-Gal in pectic substances is discussed.

Experimental evidence for a semi-flexible conformation for arabinoxylans

Purified water-soluble arabinoxylans from wheat flour were deferuloylated and fractionated into six fractions by graded ethanol precipitation. Further fractionation by HPSEC on Sephacryl S500 resulted in 48 subfractions with low polydispersity index. Conformational characteristics (persistence length q, hydrodynamic parameter ν and Mark–Houwink exponent a) were similar among all subfractions and fitted with a semi-flexible conformation, whatever their structural characteristics. Substitution degree of the xylan backbone by arabinose residues has no influence on the conformation of arabinoxylans.

Isolation and characterization of polysaccharides from Tansy

Using extraction with 0.75% aqueous ammonium oxalate, the following polysaccharide fractions were isolated: tanacetans TVF, TVS, and TVR from floscules, sprouts, and roots, respectively, of Tanacetum vulgare L., spread throughout the European North of Russia. The sugar chain of tanacetan TVF consists of D-galacturonic acid (61.4%), arabinose (14.7%), galactose (10.2%), and rhamnose (3.7%) as the main constituents as well as xylose, glucose, mannose, apiose, and 2-O-methylxylose in trace amounts. Tanacetans TVS and TVR were shown to differ in the sugar quantitative composition. They contain 67 and 28% galacturonic acid, respectively. A partial acid hydrolysis of the tanacetan TVF gave a polysaccharide fragment TVF1, alpha-1,4-D-galacturonan (GalA 98.2%). Digestion with pectinase (alpha-1,4-D-polygalacturonase) resulted in fragment TVF3, containing residues of arabinose (27.1%) and galactose (17.3%). NMR spectroscopy allowed detection of the terminal residues of alpha-Araf and beta-Galp as well as of the residues of alpha-Araf substituted in 3,5- and 5-positions. Thus, tanacetan TVF was proved to be a pectic polysaccharide.

Analysis of structural components and molecular construction of soybean soluble polysaccharides by stepwise enzymatic degradation.

Soybean soluble polysaccharides (SSPS) extracted from soybean cotyledons have a pectin-like structure. The core polysaccharides after treatments with four kinds of hemicellulases and a pectinase contained approximately equal numbers of L-rhamnose and D-galacturonate residues, suggesting the presence of the rhamnogalacturonan (RG) I structure consisting of the diglycosyl repeating unit, -4)-alpha-D-GalpA-(1-->2)-alpha-L-Rhap-(1-. The lengths of RG chains were calculated as approximately 15, 28, and 100 diglycosyl repeats. The RG components linked to each other by intervention of galacturonan (GN) chains, constituting the backbone of SSPS. All arabinose residues, which constitute 21% of total SSPS sugars, were found to be in side chains from RG regions, and this was also true for galactose residues, which constitute 50% of total sugars. Of arabinose residues, 94% are present as alpha-1,3- or alpha-1,5-arabinans, and 89% of galactose residues were present as beta-1,4-galactans. Galactan chains are modified with arabinose, xylose, fucose, and glucose at the sites close to the RG regions.

D-Galactose-Specific Sea Urchin Lectin Sugar-Specifically Inhibited Histamine Release Induced by Datura stramonium Agglutinin: Differences Between Sugar-Specific Effects of Sea Urchin Lectin and Those of D-Galactose- or L-Fucose-Specific Plant Lectins

A new sea urchin lectin from Toxopneustes pileolus, is D(+)galactose (Gal)-, D(+)fucose (Fuc)-specific. Incubation of rat peritoneal mast cells with the lectin in the presence of 0.3 mM CaCb for 10 min significantly and dose-dependently inhibited the histamine release induced by N-acetyl glucosamine (GlcNAc)-specific Datura stramonium agglutinin (DSA), an activator of the Gi-protein-dependent pathway in mast cells. This inhibition by the sea urchin lectin was sugar-specifically reversed in the presence of D(+)Gal or D(+)Fuc but not L(-)Fuc. The sea urchin lectin had no effect on the histamine release induced by compound 48/80, slightly inhibited the histamine release induced by substance P and mastoparan, and slightly enhanced the histamine release induced by melittin, but these effects were not dose-dependent. Compound 48/80, substance P, mastoparan and melittin are mast cell activators without sugar residues. It is suggested that the lectin binds to D(+)Gal residues of DSA to interfere with mast cell activation induced by DSA, a glycoprotein with arabinose and Gal residues. The effects of plant lectins with affinity to D(+)Gal, N-acetyl galactosamine and/>or sialic acid and L(-)Fuc on the histamine release induced by DSA, compound 48 /80 and substance P were also examined.

A wide diversity of sulfated polysaccharides are synthesized by different species of marine sponges

Sulfated polysaccharides were extracted from four species of marine sponges by exhaustive papain digestion. These compounds were purified by anion-exchange and gel-filtration chromatography. Analysis of the purified polysaccharides revealed a species-specific variation in their chemical composition and also in their molecular masses. In the species Aplysina fulva we found a sulfated glucan with a glycogen-like structure. The other three species contained sulfated polysaccharides with variable proportions of galactose, fucose, arabinose and hexuronic acid and also with different degrees of sulfation. Although the complex nature of these polysaccharides did not allow complete structure determination, we detected the occurrence of 4-sulfated residues of fucose and arabinose in the species Dysidea fragilis. The biological role of these sulfated polysaccharides requires further investigation. They may be involved in the species-specific aggregation of sponge cells and/or in the structural integrity of sponge, resembling the proteoglycans of mammalian connective tissues.

The composition of two Spondias gum exudates

The polysaccharides isolated from Spondias purpurea var. lutea and Spondias cytherea contain galactose, as main component, arabinose, mannose, xylose and rhamnose residues. On the other hand, glucuronic acid and its 4-0-methyl derivative are present in those polysaccharides in contrast to the presence of galacturonic acid reported for other Spondias gums. S. cytherea gum has the highest intrinsic viscosity (63 ml/g). The values of nitrogen are comparable to those observed for some Acacia included in series Vulgares. Comparison of the specific optical rotation values and the 13C-NMR spectra of the polysaccharides from S. purpurea var. lutea and S. purpurea, may be very useful to distinguish those two close botanical species. The high solubility of the Spondias gums studied and the absence of tannin may have potential industrial application therefore, it is necessary to do toxicological studies of those Spondias gums.

The isolation, preliminary structural studies, and physiological activity of water-soluble polysaccharides from the squeezed berries of the snowball treeViburnum opulus

Water-soluble polysaccharide fractions VO1–VO4 were isolated from the squeezed berries of the snowball tree (Viburnum opulus) by successive extraction with water at various temperatures and pH and with aqueous solutions of ammonium oxalate. These fractions were purified by ion-exchange chromatography on DEAE cellulose, and the homogeneity of the purified polysaccharides was determined by gel filtration on Sephacryl S-500. Acidic polysaccharides close to pectins in their sugar composition were found in all the extracts (fractions VO1-1, VO2-1, VO3-2, and VO4-2). Residues of galacturonic acid, galactose, arabinose, and (to a lesser extent) rhamnose are their main constituents. Neutral polysaccharides composed mainly of galactose and mannose residues were additionally found in fractions extracted with acidified water (pH 4.0) and with aqueous ammonium oxalate solutions. Partial acidic hydrolysis and digestion with pectinase of acidic polysaccharides indicated that their carbohydrate backbone consists of α-1,4-linked residues ofD-galacturonic acid. NMR spectra of acidic polysaccharides (fractions VO3-2 and VO3-3) confirmed this and demonstrated that their side oligosaccharide chains are composed of β-1,4-linked galactopyranose residues and of terminal and 2,5- and 3,5-substituted residues of α-arabinofuranose at a Gal : Ara ratio of 3 : 1. Some polysaccharides fromV. opulus were found to possess an immunostimulating activity: they enhance phagocytosis, in particular, the phagocytic index and the secretion of lysosomal enzymes with peritoneal macrophages. Calcium ions were found to be necessary for the appearance of the stimulating effect of acidic polysaccharides fromV. opulus.

Ferulic acid and diferulic acids as components of sugar-beet pectins and maize bran heteroxylans

Enzymatic hydrolysis of sugar-beet pulp, and subsequent isolation of feruloylated oligosaccharides, has shown that ferulic acid groups are ester-linked mainly on O-2 of arabinose residues and on O-6 of galactose residues in the pectin side-chains. After saponification of sugar-beet pulp enzymatic digests, dehydrodiferulic acids (0.14%, w/w) have also been identified and characterised as 8-5', 5-5', 8-8' and 8-O-4' isomers, suggesting that covalent cross-linking of pectic polysaccharides through diferulic bridges occurs in sugar-beet pulp. Feruloylated oligosaccharides from the side-chains of heteroxylans have been isolated from maize bran by acid hydrolysis. Ferulic acid is esterified on O-5 of arabinofuranose residues. 8-8', 8-5', 8-O-4' and 5-5' coupled dimers, which represent 2.5% (w/w) of the bran, have also been detected. It has been calculated that, in the cell wall, each heteroxylan macromolecule bore ∼ 75 esterified ferulic acid groups and could be cross-linked through ∼ 30 diferulic bridges. This result suggests a high degree of cross-linking of heteroxylans chains through ferulic acid in maize bran cell walls.

Chemical composition of the potential new oilseed cropsBarbarea vulgaris,Barbarea verna andLepidium campestre

Barbarea vulgaris, Barbarea verna and Lepidium campestre were selected as potential new oilseed crops. To evaluate the nutritional and technological quality of the seeds, the chemical composition was studied. The major constituents found were dietary fibre, crude fat and crude protein. Barbarea contained about 350 g kg−1 dietary fibre, 295 g kg −1 crude fat and 170 g kg−1 crude protein, while Lepidium contained about 400 g kg−1 dietary fibre, 200 g kg−1 crude fat and 190 g kg−1 protein. The amino acid composition was found to be suitable for human consumption when comparison with the amino acid pattern for high quality protein was made. Fatty acid composition was dominated by erucic acid in B vulgaris (28%) and B verna (50%) and by linolenic acid in L campestre (34%). Insoluble dietary fibres were dominated by Klason lignin in both Barbarea and Lepidium. Uronic acid and glucose residues were also found in large amounts. Soluble dietary fibres were dominated by uronic acid, arabinose and galactose residues. The major glucosinolates found were glucobarbarin in B vulgaris (108 μmol g−1), gluconasturtiin in B verna (106 μmol g−1) and sinalbin in L campestre (110 μmol g−1). No cyanogens were found in any of the seeds. © 1999 Society of Chemical Industry

Activity of an Aspergillus terreusα-arabinofuranosidase on phenolic-substituted oligosaccharides

The effect of phenolic substitutions on the activity of an α-arabinofuranosidase from Aspergillus terreus was investigated using feruloylated oligosaccharides isolated from plant cell walls, equivalent oligosaccharides obtained through treatment with specific ferulic acid esterases, and a synthetic lignin-carbohydrate complex (LCC). Feruloyl substituents limited the hydrolysis of arabinoxylan and arabinan oligosaccharides but only if the feruloyl group was esterified to the terminal non-reducing arabinose. Somewhat surprisingly, the LCC-model compound, in which the arabinose residue is substituted with a bulky dilignol group, was degraded by the enzyme. This indicated that the enzyme is able to approach this linkage from the xylose side.

Enzyme supplementation of wheat-based diets for broilers: 2. Effect on apparent metabolisable energy content and nutrient digestibility

Two experiments were conducted to determine the effect of enzyme supplementation on the nitrogen-corrected apparent metabolisable energy (AME n) and apparent nutrient digestibilities in ileum and excreta from male broiler chickens fed diets containing high amounts of wheat (>80%). Four different enzyme preparations were added to the wheat-based diets in varying levels and combinations. The difference between Experiments 1 and 2 consisted in the addition of different enzymes and enzyme levels. Excreta and ileal content were collected from broiler chickens at 3 and 6 weeks of age. At 3 weeks of age enzyme supplementation increased ( P<0.0001) the AME n from an average value of 13.86 MJ kg −1 dry matter (DM) to an average of 14.60 MJ kg −1 DM in the two experiments. The apparent digestibility of protein (APD) and fat (AFD) were improved significantly as a result of enzyme addition in both experiments. At 3 weeks of age, improvements ( P<0.05) in the ileal AFD and APD were on average 13% and 6%, respectively. The effect of enzyme supplementation on AFD measured in excreta from broiler chickens showed the same pattern. The positive effect of enzyme addition on the overall nutrient digestibility and AME n was reflected in weight gain and feed conversion efficiency (FCE). Significant improvements in AME n, APD, and AFD were still present in most of the groups fed with enzyme-supplemented diets at 6 weeks of age. The effect of enzyme addition, however, was less pronounced, especially in Experiment 1 where the ileal APD of broiler chickens did not differ significantly from the control group. Apparent starch digestibility (ASD), measured in Experiment 2, was very high in all groups, including the control; however, enzyme supplementation increased ASD ( P<0.001) in ileum and excreta at both 3 and 6 weeks of age. The digestibility of total non-starch polysaccharides (NSP) in excreta was improved significantly ( P<0.01) as a result of enzyme supplementation (Experiment 2). In addition, pH of caeca content decreased ( P<0.02) in broiler chickens fed with enzyme-supplemented diets when compared with the control group. Decreased pH could indicate microbial fermentation of unabsorbed NSP residues and nitrogenous compounds. Overall, the results demonstrated that the nutritive value of wheat-based diets to broiler chickens improve enzyme supplementation. The apparent digestibility of total NSP and of arabinose and xylose residues improved ( P<0.02) in the enzyme-supplemented diets indicating that the enzymes were able to break down the cell wall NSP to a certain extent.

Glycoinositol phospholipids from Endotrypanum species express epitopes in common with saccharide side chains of the lipophosphoglycan from Leishmania major.

We have characterized glycoinositol phospholipids (GIPLs) from three strains of the trypanosomatid parasites Endotrypanum schaudinni and Endotrypanum monterogeii. Methanolysis of the intact GIPLs liberated methyl esters of tetracosanoic acid, docosanoic acid, octadecanoic acid and hexadecanoic acid and C20 and C21 phytosphingosines. Phosphoinositol oligosaccharides were released from the GIPLs by mild base treatment, and their structures were determined by compositional analysis, fast-atom-bombardment MS and NMR spectroscopy. Similar compounds were detected in all three strains, although their relative proportions varied. The predominant components in E. schaudinni strain LV59 and E. monterogeii LV88 were Galpbeta1-3Galpbeta1-3Manalpha1-3Manalpha1-4G lcNalpha1-6Ins-1-P and Arapbeta1-2Ga lpbeta1-3Galpbeta1-3Manalpha1-3Manalpha1-4Glc Nalpha1-6Ins-1-P, and the major phosphoinositol oligosaccharide in E. schaudinni LV58 was the hybrid-type GIPL Manalpha1-2(EtNP-6)Manalpha1-6(Galpbeta1-3Man alpha1-3)Manalpha1-4GlcN alpha1-6Ins-1-P (where EtNP is ethanolamine phosphate). Several minor oligosaccharides containing additional galactose and/or arabinose residues were also detected.

Developmental changes of sugar contents in the gall on the leaf of elm (Zelkowa serrata Makino) formed byParacolopha morrisoni Baker (homopetra)

To understand cell wall polysaccharide synthesis and the role of gall in interaction with aphids, the changes of sugar contents in the galls during their growth and development were determined from May 2 to June 8, 1996. The sugar content in the symplastic (MeOH and hot water) fractions decreased as the developmental stages progressed. In the cell wall fraction, the amount of pectic substances (2-3 mg per gram fresh weight) did not change. The hemicellulosic substance increased by 40% from May 14 to May 31. Among the neutral sugar components of hemicellulosic polysaccharides, xylose and arabinose contents increased during development of the gall, suggesting that xylans with arabinose residues were massively synthesized. On the other hand, glucose content decreased during development of the gall. The cellulose substance consistently increased 5 folds from May 2 to 31. The relationship between the aphid and the changes in sugar contents of cell walls during the development of aphid and the gall formation was discussed.

Differential targeting of closely related ECM glycoproteins: the pherophorin family from Volvox.

The alga Volvox carteri represents one of the simplest multicellular organisms. Its extracellular matrix (ECM) is modified under developmental control, e.g. under the influence of the sex-inducing pheromone that triggers development of males and females at a concentration below 10(-16) M. A novel ECM glycoprotein (pherophorin-S) synthesized in response to this pheromone was identified and characterized. Although being a typical member of the pherophorins, which are identified by a C-terminal domain with sequence homology to the sex-inducing pheromone, pherophorin-S exhibits a completely novel set of properties. In contrast to the other members of the family, which are found as part of the insoluble ECM structures of the cellular zone, pherophorin-S is targeted to the cell-free interior of the spherical organism and remains in a soluble state. A main structural difference is the presence of a polyhydroxyproline spacer in pherophorin-S that is linked to a saccharide containing a phosphodiester bridge between two arabinose residues. Sequence comparisons indicate that the self-assembling proteins that create the main parts of the complex Volvox ECM have evolved from a common ancestral gene.

Chemical Composition of Barley Samples Focusing on Dietary Fibre Components

Abstract Grain samples of 16 barleys, including covered and naked types, were selected to represent genotypes that were known to vary in their contents of protein, amylose and amylopectin and β-glucan contents of wort or grain. The chemical compositions of the samples were analysed, focusing particularly on dietary fibre components. Covered and naked barley genotypes differed in their average contents of non-starch polysaccharides, Klason lignin and ash. High amylose types had higher total β-glucan values (6·3% and 7·9%) than waxy types (5·4%–5·8%). The content of extractable β-glucan was only slightly correlated with total β-glucan content. On average, 44% of the xylose residues in water extractable arabinoxylans were substituted with arabinose residues. The presence of considerable amounts of xylopyranose substituted only at O-2 was detected in water extractable arabinoxylans.

Water unextractable polysaccharides from three milling fractions of rye grain

Water unextractable material from bran, an intermediate milling fraction and sieved flour of rye grain were sequentially extracted at room temperature with saturated barium hydroxide, water, 4 M potassium hydroxide and water followed by extraction with 2 m potassium hydroxide in a boiling water bath, giving repeatable recoveries of extracts and polysaccharide residue compositions in collected fractions. Total recoveries of polysaccharide residues in extracts and residue from the different water unextractable materials were 78–88%. Extracts in which 90–93% of the carbohydrates were arabinose and xylose residues were obtained by extraction with saturated barium hydroxide. Subsequent extraction with water yielded a fraction in which 64–68% of the carbohydrates were glucose residues. The extraction with hot alkali resulted in extracts in which 85–89% of the carbohydrates were arabinose and xylose residues. The ara/xyl ratio in the collected fractions ranged from 0.1–1.3, with the lowest ratios in fractions that precipitated after neutralisation of the 4 m potassium hydroxide extract and the highest ratios in the unextractable residues. Structural characterisation with 1H-NMR spectroscopy revealed varying substitution patterns for arabinoxylans in the different extracts and that glucose residues in the extracts essentially originated from mixed-linked β-glucan. The proportion of disubstituted xylose residues was lower in barium hydroxide extracts compared to the other main extracts. A highly branched heteroxylan was extracted with hot alkali. The polysaccharides found in the corresponding extracts for all the starting materials had generally similar structural features, but the yield differed considerably.