D-galacturonic Acid Residues Research Articles

Pectin Isolated from the Midrib of Leaves ofNicotiana tabacum

A pectin isolated from tobacco midrib contained residues of d-galacturonic acid (83.7%), L-rhamnose (2.2%), l-arabinose (2.4%) and d-galactose (11.2%) and small amounts of d-xylose and d-glucose. Methylation analysis of the pectin gave 2, 3, 5-tri- and 2, 3-di-O-methyl-l-arabinose, 3, 4-di- and 3-O-methyl-l-rhamnose and 2, 3, 6-tri-O-methyl-d-galactose. Reduction with lithium aluminum hydride of the permethylated pectin gave mainly 2, 3-di-O-methyl-d-galactose and the above methylated sugars. Partial acid hydrolysis gave homologous series of β-(1 → 4)-linked oligosaccharides up to pentaose of d-galactopyranosyl residues, and 2-O-(α-d-galactopyranosyluronic acid)-l-rhamnose, and di- and tri-saccharides of α-(1 → 4)-linked d-galactopyranosyluronic acid residues.These results suggest that the tobacco pectin has a backbone consisting of α-(1 → 4)-linked d-galactopyranosyluronic acid residues which is interspersed with 2-linked l-rhamnopyranosyl residues. Some of the l-rhamnopyranosyl residues carry substituen...

Pectin isolated from the midrib of leaves of Nicotiana tabacum.

A pectin isolated from tobacco midrib contained residues of d-galacturonic acid (83.7%), L-rhamnose (2.2%), l-arabinose (2.4%) and d-galactose (11.2%) and small amounts of d-xylose and d-glucose. Methylation analysis of the pectin gave 2, 3, 5-tri- and 2, 3-di-O-methyl-l-arabinose, 3, 4-di- and 3-O-methyl-l-rhamnose and 2, 3, 6-tri-O-methyl-d-galactose. Reduction with lithium aluminum hydride of the permethylated pectin gave mainly 2, 3-di-O-methyl-d-galactose and the above methylated sugars. Partial acid hydrolysis gave homologous series of β-(1 → 4)-linked oligosaccharides up to pentaose of d-galactopyranosyl residues, and 2-O-(α-d-galactopyranosyluronic acid)-l-rhamnose, and di- and tri-saccharides of α-(1 → 4)-linked d-galactopyranosyluronic acid residues.These results suggest that the tobacco pectin has a backbone consisting of α-(1 → 4)-linked d-galactopyranosyluronic acid residues which is interspersed with 2-linked l-rhamnopyranosyl residues. Some of the l-rhamnopyranosyl residues carry substituen...

Structure of sugar-beet pectin

The results are given of a chemical study of one of the fractions of ammonium pectate, PAP-12 with a molecular weight of 18,000, obtained from sugar-beet pulp. PAP-12 contains mainly D-galacturonic acid residues in the pyranose form linked by α-1→4 bonds, and also rhamnose, galactose, and traces of arabinose.

Somatic Antigens of Shigella

The specific polysaccharide was obtained from the lipopolysaccharide of Shigella newcastle by mild acid hydrolysis and further purified by permeation chromatography on Sephadex G-50. It was found to consist of L-rhamnose, 2-acetamido-2-deoxy-D-galactose, D-galacturonic acid residues and O-acetyl groups in the molar ratios of 2:1:1:1. On the basis of 1H and 13C nuclear magnetic resonance spectroscopy, methylation analysis, partial acid hydrolysis, Smith degradation, and chromium trioxide oxidation, the following structure can be assigned to the repeating oligosaccharide unit of the polysaccharide:-4)DGalA(beta 1-3)DGalNAc-(beta 1-2)LAc3Rha(alpha 1-2)LRha(alpha 1-, where GalA = galacturonic acid. GalNAc = N-acetylgalactosamine, Ac3Rha = 3-O-acetylrhamnose. The structural and immunochemical data presented prove that Sh. newcastle lipopolysaccharide belongs to a 'non-classical' type of somatic antigens with acidic O-specific polysaccharide chains.

The mucilage of Opuntia ficus-indica

The mucilage extracted from the cladodes (modified stems) of Opuntia ficus-indica contains residues of d-galactose, d-xylose, l-arabinose, l-rhamnose, and d-galacturonic acid. Seasonal variation in the sugar composition of the mucilage has been investigated. Fractionation studies indicate that the mucilage is essentially homogeneous. The rate of release of the constituent sugars and the change in optical rotation on mild hydrolysis coupled with the results of chromic acid oxidation suggest that the mucilage contains α-arabinofuranosyl, β-xylopyranosyl, β-rhamnopyranosyl, β-galactopyranosyl, and α-galactopyranosyluronic acid residues. The results also suggest a core containing galacturonic acid, rhamnose, and galactose, to which xylose and arabinose are attached in peripheral positions.

Structure of a new acid-polysaccharide from the bark of Pterospermum acerifolium

A new acid-polysaccharide isolated from the bark of Pterospermum acerifolium N.O. Sterculiaceae has been shown to be composed of residues of D-galacturonic acid, D-galactose, and L-rhamnose in the molar ratio 5 : 3 : 3, repectively. Partial acid hydrolysis gave three oligosaccharides, 2-O-(α-D-galactopyranosyl uronic acid)-L-rhamnose, 4-O-(α-D-galactopyranosyl uronic acid)-D-galacturonic acid, and O-D-galactopyranosyl uronic acid(1 → 2)-O-L-rhamnopyranosyl-(1 → 4)-D-galactose. The various glycosidic linkages have been determined by the products from hydrolysis of the methylated polysaccharide and confirmed by periodate oxidation of the polysaccharide.

Structure of the pectic acid of Matricaria chamomilla

The main features of the structure of the pectic acid from the racemes of German chanomile have been established. The main polysaccharide chain consists of D-galacturonic acid residues in the pyranose form with α-1→4 bonds. Isolated single-unit branches of the neutral monosaccharides galactose, arabinose, and xylose are possible. L-rhamnose, which was isolated from the degradation products of the permethylated pectic acid only in the form of 3,4-di-O-methyl-L-rhamnose is apparently included in the main polysaccharide chain.

Pectin substances ofChara aculeolata

The carbohydrate complex of the Chara algaChara aculeolata Kutz includes an acid polysaccharide similar to the pectin substances of higher plants. It is based on a fragment constructed of α-1→4 bound residues of D-galacturonic acid in the pyranose form. The pectin is characterized by a high homogeneity, a considerable content of D-galacturonic acid, and a low degree of acidification of the carboxy groups.

The structure of degraded bael ( Aegle marmelos) gum

Mild, acid hydrolysis of purified bael gum yielded a homogeneous, degraded product consisting of residues of L-arabinose, D-,galactose, L-rhamnose, and D-galacturonic acid in the molar proportions of 1:19:1:2. The homogeneity of this degraded gum was proved from electrophoretic data. Hydrolysis of one mole of the fully methylated polysaccharide gave ( a) from the neutral part, 2,3,4,6-tetra- O-methyl- D-galactose (12 moles), 3,4-di- O-methyl- L-rhamnose (2 moles), 2,5-di- O-methyl- L-arabinose (1 mole), 2,4,6-tri- O-methyl- D-galactose (8 moles), 2,3-di- O-methyl- L-arabinose (1 mole), 2,4-di- O-methyl- D-galactose (12 moles), and 2- O-methyl- D-galactose (2 moles), and ( b) from the acidic part, 2,3,4-tri- O-methyl- D-galacturonic acid (1 mole), 2,4,6-tri- O-methyl-3- O-(2,3,4-tri- O-methyl- D-galactopyranosyluronic acid)- D-galactose (2.5 moles), and 2,4,6-tri- O-methyl-3- O-[2,4,6-tri- O-methyl-3- O -(2,3,4-tri- O-methyl- D-galactopyranosyluronic acid)- D-galactopyranosyl]- D-galactose (1 mole). The results of periodate oxidation were in agreement with those of methylation studies. Smith, and Barry, degradation studies on the degraded gum were also conducted. From the results of all these experiments, a tentative structure for the average repeating-unit of the degraded gum is proposed.

The structure of the polyuronide of the leaves of the sugar beet

The polygalacturonide of the pectin of sugar-beet leaves has been studied. It has a linear carbohydrate chain consisting of D-galacturonic acid residues in the pyranose form linked by α-(1→4) bonds.

Analysis of some partly and fully esterified oligogalactopyranuronic acids by p.m.r. spectrometry at 220 MHz

The p.m.r. spectra of mono-, di-, tri-, tetra-, and penta-galactopyranuronic acids (1–5), the corresponding fully esterified methyl esters (6–10), the partly esterified di- (11) and tri-galactopyranuronic acids (12, 13), and the unsaturated di-, tri-, and tetra-galactopyranuronic acids (14–16) were measured on solutions in D2O at 220 MHz at a pH of 1 and 6. Observation of doublets (J 4 Hz) in the range δ 4.90–5.05 p.p.m. indicates the site of esterification in the non-reducing or reducing sugar residue. Esterification of the sugar residue at the non-reducing end can be deduced from both the presence of a methyl resonance peak at δ 3.80 and the indifference of the signal at δ 4.35 (H-4) to the change in pH. The δ values and coupling constants confirm that all the d-galacturonic acid residues have the CI conformation and are α-(1→4)-linked. In the unsaturated oligogalactopyranuronic acids, the double bond is located between C-4 and C-5 of the sugar unit at the non-reducing end. The 4-deoxyhex-4-enopyranosyluronic acid residue occurs in the 2H1(d) conformation. Compound 11 was identified as O-(α-d-galactopyranosyluronic acid)-(1→4)-(methyl α,β-d-galactopyranuronate). Compounds 12 and 13 each consisted of a mixture of the three possible isomers; preference for the site of esterification decreases in the order reducing sugar unit, non-reducing sugar unit, sugar unit at the non-reducing end.

Acid and Enzymatic Hydrolysis of an Acidic Polysaccharide from Soy Sauce

Mild acid hydrolysis of an acidic polysaccharide (APS-I) from soy sauce resulted in a degraded polysaccharide (DPS), the mixture of neutral sugar, D-galacturonic acid, its α-1,4-linked homologous di- and trisaccharides, and acidic oligosaccharides containing residues of D-galacturonic acid and L-rhamnose. Besides the above-mentioned sugars, an aldobiouronic acid containing D-xylose moiety was also yielded in the enzymatic hydrolysates with a crude polysaccharidase preparation. However, only a β-l, 4-galactobiose was isolated from the lower molecular fraction of enzymatic digest of APS-I with a typical hemicellulase preparation. DPS containing 83% of D-galacturonic acid was able to be degraded by endo-polygalacturonase, but APS-I was not because of its highly was discussed on the basis of these results, periodate oxidation study.

The pectic substances of zosteraceae: Part IV. Pectinase digestion of zosterine

Pectinase digestion of zosterine furnished apiogalacturonan (AGU), an oligosaccharide mixture, and D-galacturonic acid, thereby suggesting a structure that contains, in part, galacturonan chains free of glycosidic bonds with neutral sugars. AGU, which was homogeneous and resistant to pectinase, was composed of D-galacturonic acid and D-apiose residues in a ratio of ≈4:5. Partial hydrolysis with acid, periodate oxidation, and methylation studies proved AGU to possess a branched structure with a linear, α-(1→4)-linked D-galacturonan chain substituted in the 2-, 3-, or 2,3-positions by D-apiose residues. Pseudoaldobiouronic acids, consisting of D-xylose or L-arabinose residues linked to D- galacturonic acid, were isolated from the oligosaccharide mixture, thereby demonstrating the presence of glycosidic bonds between the galacturonan chain and neutral fragments of zosterine.

Polysaccharide conformation. Part VII. Model building computations for α-1,4 galacturonan and the kinking function ofL-rhamnose residues in pectic substances

D-Galacturonic acid residues in α-1,4 linked chains are shown, by 1H n.m.r. spectroscopy of oligomers in solution and by mathematical model-building to have the Reeves C1 conformation. The probable conformation of the polymer in the solid state is also derived. Calculations show that multiple-helix formation is impossible for α-1,4-galacturonan; therefore, despite physical similarities, the gel properties of pectins and pectates cannot be explained in the same terms as for agar and carrageenans. There is, however, a strong analogy with the other biological-network polysaccharides in that anomalous units are interspersed to form ‘kinks’ which interrupt any tendency to an ordered chain conformation; these units are L-rhamnose in pectic substances and correspond to galactose 6-sulphate in carrageenans and to L-iduronic or D-glacuronic acid in mucopolysaccharides.

Isolation and partial characterization of apiogalacturonans from the cell wall of Lemna minor.

1. A mild, reproducible extraction procedure, using 0.5% ammonium oxalate, was developed for the isolation of polysaccharides containing d-apiose from the cell wall of Lemna minor. On a dry-weight basis the polysaccharide fractions extracted with ammonium oxalate made up 14% of the material designated cell walls and contained 20% of the d-apiose originally present in the cell walls. The cell walls, as isolated, contained 83% of the d-apiose present in L. minor. 2. After extraction with ammonium oxalate, purified polysaccharides were obtained by DEAE-Sephadex column chromatography and by fractional precipitation with sodium chloride. With these procedures the material extracted at 22 degrees C could be separated into at least five polysaccharides. On a dry-weight basis two of these polysaccharides made up more than 50% of the material extracted at 22 degrees C. There was a direct relationship between the d-apiose content of the polysaccharides and their solubility in sodium chloride solutions; those of highest d-apiose content were most soluble. 3. All the polysaccharides isolated appeared to be of one general type, namely galacturonans to which were attached side chains containing d-apiose. The d-apiose content of the apiogalacturonans varied from 7.9 to 38.1%. The content of esterified d-galacturonic acid residues in all apiogalacturonans was low, being in the range 1.0-3.5%. Hydrolysis of a representative apiogalacturonan with dilute acid resulted in the complete removal of the d-apiose with little or no degradation of the galacturonan portion. 4. Treatment of polysaccharide fractions with pectinase established that those of high d-apiose content and soluble in m-sodium chloride were not degraded, whereas those of low d-apiose content and insoluble in m-sodium chloride were extensively degraded. When the d-apiose was removed from a typical pectinase-resistant polysaccharide, the remainder of the polysaccharide was readily degraded by this enzyme. 5. Periodate oxidation of representative polysaccharide fractions and apiogalacturonans and determination of the formaldehyde released showed that about 50% of the d-apiose molecules were substituted at either the 3- or the 3'-position.

The pectin of ginseng. The structure of the poly-galacturonide

The partial hydrolysis of the pectin ofPanax ginseng C. A. Mey gives a polygalacturonide which has a linear carbohydrate chain consisting of residues of D-galacturonic acid in the pyranose form linked by α-(1 → 4)-bonds.

The Pectic substances of Zosteraceae: Part II. The structural features of the pectic acid

The pectic acid obtained on partial hydrolysis of zosterine, which is a pectic polysaccharide of various Zosteraceae plants, has been shown to be a linear galacturonan containing (1→4)- and, possibly, (1→5)-linked residues of D-galacturonic acid.

Some structural features of Panax ginseng C. A. Mey pectin

The pectin isolated from roots of Panax ginseng C. A. Mey, contains residues of d-galacturonic acid, d-galactose, and l-arabinose, as main components, and those of d-xylose, l-rhamnose, and an unidentified sugar, as minor components of its carbohydrate chain. On partial hydrolysis with acid, the pectin afforded a galacturonan having a linear chain of (1 → 4)- and, possibly, (1 → 5)-linked α- d-galacturonic acid residues. Pectinase digestion of the pectin furnished a neutral, pectic polysaccharide in which l-arabinofuranose residues apparently occur in the exterior chains. On partial hydrolysis with acid, the polysaccharide afforded a branched galactan and an acidic heteropolysaccharide. The galactan contains chains of (1 → 3)- and (1 → 6)-linked d-galactopyranose residues. The heteropolysaccharide appears to contain sequences involving d-galactose residues, and others involving residues of d-galacturonic acid, d-xylose, and l-rhamnose.

Properties of a polygalacturonic acid-synthesizing enzyme system from Phaseolus aureus seedlings

A cell-free enzyme system from Phaseolus aureus seedlings, which is capable of catalyzing the synthesis of polygalacturonic acid, was found to utilize UDP- d-galacturonic acid in preference to other nucleoside diphosphate d-galacturonic acid derivatives. It did not incorporate d-galacturonic acid residues from UDP-methyl- d-galacturonate into polygalacturonic acid. Maximum rate of polymerization occurs where preparations from seedlings germinated for 3 days are reacted with substrate at 30 °, pH 6, in the presence of 1.7 m m MnCl 2 and 0.4 m sucrose. The enzyme system has an apparent Michaelis constant of 1.7 × 10 −6 m, and at a substrate concentration of 3.7 × 10 −5 m will catalyze the polymerization of d-galacturonic acid residues at the rate of 4.7 mμmoles per milligram protein per minute. The enzyme is inactivated spontaneously, the rate of which is a function of temperature and pH. The addition of MnCl 2 delays inactivation.

Myo-inositol-2-t Incorporation by Germinating Pollen

POLLEN of pear (Pyrus communis) germinated in vitro in 10−3 M myo-inositol-2-t rapidly incorporates label into its 70 per cent ethanol-insoluble polysaccharides1. Analysis of pectinase hydrolysates recovered nearly all this label in D-galacturonic acid and L-arabinose residues. Other investigations2,3 have shown that this conversion is highly specific and that the original carbon sequence in inositol is conserved. Hexose constituents present in these 70 per cent ethanol-insoluble pollen residues, principally D-glucose and D-galactose, are essentially unlabelled.