Mammalian-lung galactan

Exopolysaccharides of Agrobacterium tumefaciens and Rhizobium meliloti, containing d-glucose, d-galactose, pyruvic acid, and O-acetyl groups in the approximate proportions 6:1:1:1.5, were analysed by methylation. They were found to contain the following main structural units (all β-glycosidic): chain residues of (1→3)-linked d-glucose (24%), (1→3)-linked d-galactose (15%), (1→4)-linked d-glucose (20%), and (1→6)-linked d-glucose (18%); (1→4,1→6)-linked branching residues of d-glucose (12%), and terminal d-glucose residues substituted at positions 4 and 6 by pyruvate (11%). Uronic acid-containing exopolysaccharides of Rhizobium leguminosarum, R. phaseoli, and R. trifolii contained d-glucose, d-glucuronic acid, d-galactose, pyruvic acid, and O-acetyl groups in the approximate proportions 5:2:1:2:3. Methylation gave identical patterns of methylated sugar components, from which the following structural elements were deduced: chain residues of (1→3)-linked d-glucose substituted at positions 4 and 6 by pyruvate (13%), (1→4)-linked d-glucose (32%), and (1→4)-linked d-glucuronic acid (20%); (1→4,1→6)-linked branching residues of d-galactose and/or d-glucose (13%), and terminal d-glucose and/or d-galactose residues substituted at positions 4 and 6 by pyruvate (13%).     

The structure of a dextran produced by Leuconostoc mesenteroides NRRL B-1397: the linkages and length of the branches

The structure of a dextran produced by Leuconostoc mesenteroides NRRL B-1397 has been investigated in relation to its immunological properties. The methylated dextran yielded on acid hydrolysis 2,3,4,6-tetra-, 2,3,4-tri-, 3,4,-di-, and 2,4-di-O-methyl-d-glucose, in the molar ratio of 1.0:3.1:0.7:0.2, together with a trace of 2,4,6-tri-O-methyl-dglucose, indicating that the branches occur mainly at O-2 and the remainder at O-3. A carboxyl-dextran, obtained by catalytic oxidation of the dextran to convert the terminal, non-reducing d-glucose residues d-glucuronic acid residues, was partially hydrolyzed with acid. Fractionation gave 2-O-(α-d-glucopyranosyluronic acid) d-glucose (major), 6-O-(α-d-glucopyranosyluronic acid)-d-glucose, and mixtures of aldotri-, aldotetra-, and aldopentaouronic acid that contain both (1 → 6)- and (1 → 2)-d-glucosidic linkages. It is concluded that the branches at O-2 are mainly single d-glucose units, whereas those occurring at O-3 may be longer than two glucose units, forming a highly branched structure having an average repeating- unit of 5 sugar residues.     

Structural features of two amyloids from the hemi-cellulosic fraction of field-bean (Dolichos lablab) hulls

Two amyloid-type fractions were isolated from field-bean (Dolichos lablab) hulls by 10% alkali extraction followed by acetylation and solvent fractionation. The major, chloroform-insoluble fraction and a minor, chloroform-soluble fraction were found to be homogeneous in sedimentation analysis and molecular-sieve chromatography. The polysaccharides contained xylose and glucose in various proportions. Methylation analysis, periodate oxidation, Smith degradation, oxidation by chromium trioxide, and oligosaccharide studies indicated a new type of structure for the major fraction (glucose:xylose ratio of 1.9:1) in that it had a backbone of (1→4)-linked β-d-glucose residues interspersed with single or multiple residues of (1→4)-linked β-d-xylose, and to which some single d-xylosyl groups are attached through O-6 of d-glucose. In contrast, the minor fraction (glucose:xylose ratio of 1:3.7) had a backbone of (1→4)-linked β-d-xylose interspersed with (1→4)-β-d-glucose and having a side chain of d-xylose, attached through O-6 of d-glucose. The third fraction was found to be a mixture of linear (1→4)-d-glucan and (1→4)-d-xylan.     

Investigations on the fibers of pineapple [Ananas comosus (L.) Merr.] leaves: Structural study of the hemicellulose

Investigations on the hemicellulose released from extractive-free, delignified pineapple [Ananas comosus (L.) Merr.] leaf fiber revealed that it consists of (1→4)-linked d-xylopyranosyl residues in the main chain, from which branches of 4-O-methyl-d-glucopyranosyluronic acid, d-xylopyranosyl, and l-arabinofuranosyl groups originate from O-2 of the d-xylosyl residues.     

Chemical structures in a lignin-carbohydrate complex isolated from the bovine rumen

The soluble, lignin-carbohydrate complex (LCC) from the rumen fluid of steers fed a diet of pure spear grass (Heteropogon contortus) has been purified by gel filtration. The purified LCC contained 7.4% of carbohydrate which, on hydrolysis, gave d-glucose, d-xylose, l-arabinose, l-rhamnose, and traces of d-galactose and d-mannose. The structure of the LCC was examined by methylation analysis, using g.l.c.-m.s. for the unequivocal classification of the sugar derivatives. d-Glucose, d-xylose, and l-rhamnose were shown to be glycosidically linked to lignin. Some of the d-glucosyl residues carry other (1→4)-linked d-glucose units, and some of the d-xylosyl residues bear other (1→4)-linked d-xylose units and (1→3)-linked l-arabinofuranosyl groups. The major carbohydrate component is a single d-glucopyranosyl group. The LCC was subjected to various chemical treatments in an investigation of the chemical nature of the bonding between lignin and the carbohydrates. d-Glucose could be enzymically hydrolyzed from the LCC, but only with a very high concentration of β-d-glucosidase. The presence of lignin in rumen LCC has been confirmed by nitrobenzene oxidation, vanillin and syringaldehyde being identified by g.l.c.-m.s. as oxidation products from both the original spear grass and the LCC.     

Bis(2-acetamido-3,4,6-tri-O-acetyl-2-deoxy-β-D-glucopyranosyl)amine obtained by a fusion reaction

A unique, alkali-soluble polysaccharide has been isolated from the cell walls of the basidiomycete Coprinus macrorhizus microsporus. The polysaccharide, which is primarily a glucan, contains a large proportion of α-(1→4)-linked d-glucose residues and a smaller amount of β-(1→3) and (1→6) linkages, as suggested by methylation, partial acid hydrolysis, periodate oxidation, and enzymic studies. Hydrolysis of the methylated polysaccharide gave equimolar amounts of 2,4-di- and 2,3-di-O-methyl-d-glucose; no 2,6-di-O-methyl-d-glucose was identified, indicating the absence of branch points joined through O-1, O-3, and O-4. The isolation and identification of 2-O-α- glucopyranosylerythritol from the periodate-oxidized polysaccharide suggests that segments of the a-(1→4)-linked d-glucose residues are joined by single (1→3)-linkages. An extracellular enzyme-preparation from Sporotrichum dimorphosporum (QM 806) containing both β-(1→3)- and α-(1→4)-d-glucanohydrolase activity released 76% of the reducing groups from the polysaccharide. The polysaccharide also contains minor proportions of xylose, mannose, 2-amino-2-deoxyglucose, and amino acids.     

Characterization of a water-soluble glucan from angelica acutiloba

A water-soluble glucan, AR-Glucan, from the roots of Angelica acutiloba was obtained homogeneous as determined by ultracentrifugal analysis, electrophoresis, and gel filtration. AR-Glucan was composed Of d-glucose, and its MW was estimated to be 13 500. Methylation analysis indicated that AR-Glucan contained 4-O- and 4,6-di-O-substituted glucosyl residues. ¹H and ¹³C NMR data accorded with the results of methylation analysis, and the glycosidic linkages in AR-Glucan were shown to have the α-configuration. The results of β-amylase, α-amylase, and pullulanase treatments of AR-Glucan showed that it contained (1 → 4) linked α-d-glucosyl side chains of long chain length such as amylopectin. Thus, AR-Glucan is a (1 → 4) linked α-d-glucan to which are attached glucosyl side chains at O-6 of the glucosyl residues of the main chain.     

Structural features of a rye-bran arabinoxylan with a low degree of branching

Two fractions (AX-1 and AX-II) of an l-arabino-d-xylan with a low degree of branching were isolated from rye bran by different extraction procedures with and without a chlorite-delignification step. The yields and compositions of AX-I and AX-II were similar, but the d.p. of AX-II was ∼100 units higher. AX-I was shown by partial hydrolysis, methylation analysis, and ¹³C-n.m.r. spectroscopy to contain a backbone of (1→4)-linked β-d-xylopyranosyl residues substituted with single α-l-arabinofuranosyl groups at position 3 of every sixth or seventh d-xylosyl residue.     

Structural investigations of two capsular polysaccharides from cryptococcus neoformans

Two capsular polysaccharides from Cryptococcus neoformans serotype A have been shown to be chemically equivalent. One of these polysaccharides was further investigated and shown to consist of a chain of (1→3)-linked d-mannosyl residues, each of which is substituted at O–2 by a d-glucosyluronic acid or d-xylosyl group.     

Strucrural investigation of Klebsiella serotype K7 polysaccharide

Methylation analysis of and partial hydrolysis studies on the Klebsiella K7 capsular polysaccharide and its carboxyl-reduced derivative indicated the recurrence of D-glucopyranuronic acid, D-mannopyranose, and D-glucopyranose residues, linearly linked in a specific manner, in the molecular structure. D-Galactopyranose and pyruvic acid residues are linked to the main chain on the D-mannose residues (at O-3) and the D-glucose residues (at O-4 and O-6), respectively; the simplest interpretation of this evidence is that nine sugar residues and pyruvic acid constitute a repeating unit. The sequence →3)-β-D-GlcAp-(1→2)-α-D-Manp-(1→2)-α-D-Manp-(1→3)-D-Glcp→ was demonstrated by the isolation from the polysaccharide of an aldotetraouronic acid of this structure.     

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.     

Isolation from a softwood xylan of oligosaccharides containing two 4-O-methyl-d-glucuronic acid residues

Partial hydrolysis of a larch arabino(4-O-methylglucurono)xylan afforded two series of oligouronides composed of 4-O-methyl- d-glucuronic acid and d-xylose residues. The first series included aldouronic acids up to the aldopentaouronic acid. Methylation analysis indicated that the aldopentao- and aldotetrao-uronic acids were mixtures of isomers. One aldotetraouronic acid was isolated and identified as O-β-d-Xylp-(1 → 4)-O-β-d-Xylp-(1 → 4)-O-(4-O-Me-α-d-GlcAp)-(1 → 2)-d-Xyl. The two isomeric aldotriouronic acids were separated from each other. The acids of the second series, which were composed of two uronic acids and 2-4 d-xylose residues, were identified as follows: O-β-d-Xylp-(1 → 4)-O-(4-O-Me-α-d-GlcAp)-(1 → 2)-O-β-d-Xylp-(1 → 4)-O(4-O-Me-α-d-GlcAp)-(1 → 2)-O-β-d-Xylp-(1 → 4)-d-Xyl, O-(4-O-Me-α-d-GlcAp)-(1 → 2)-O-β-d-Xylp-(1 → 4)-O-(4-O-Me-α-d-GlcAp)-(1 → 2)-O-β-d-Xylp-(1 → 4)-O-β-d -Xylp-(1 → 4)-D-Xyl, O-(4-O-Me-α-d-GlcAp)-(1 → 2)-O-β-d-Xylp-(1 → 4)-O-(4-O-Mec-α-d-GlcAp)-(1 → 2)-O-β-d-Xylp-(1 → 4)-D-Xyl, and O-(4-O-Me-α-d-GlcAp)-(1 → 2)-O-β-d-Xylp-(1 → 4)-O-(4-O-Me-α-d-GlcAp)-(1 → 2)-D-Xyl. The first three compounds were new acidic oligosaccharides. The 4-O-methyl-d-glucuronic acid in the second series was present in a larger proportion than in the first series, indicating that a large proportion of the uronic acid side-chains were located on two contiguous D-xylose residues in the backbone of the softwood xylan.     

Isolation and characterization of β-d-glucan,heteropolysaccharide, and trehalose components of the basidiomycetous lichen Cora pavonia

Cora pavonia, a lichen having a basidiomycetous mycobiont, is rich in protein (36%), of which 10% is tyrosine. α,α-Trehalose is present and was isolated in 4.4% yield. The lichen was found to contain polysaccharides typical of basidiomycetes and different from those of ascomycetes and ascomycetous lichens. Isolated and characterized were a β-d-glucan and a heteropolysaccharide containing l-rhamnose, l-fucose, d-xylose, d-mannose, d-glucose, and d-galactose. The β-d-glucan was highly branched with 21% of nonreducing end-groups, contained 3-O-, 6-O-, and 3,6-di-O-substituted β-d-glucopyranosyl units, and had a main chain consisting of (1→3)- and (1→6)-links. The heteropolysaccharide component contained mainly mannose and xylose, having a mannose-containing nucleus and a main chain with preponderant (1→3)-linked α-d-mannopyranosyl residues. These were unsubstituted (10%), and 4-O- (10%) and 2,4-di-O-substituted (10%) with residues of β-d-xylopyranose. On methylation analysis of the heteropolysaccharide, a capillary column of DB-210 proved to be particularly useful for gas-liquid chromatographic resolution of partially O-methylated alditol acetates.     

Structural studies on the specific capsular polysaccharide from Rhizobium trifolii, TA-1

The repeating unit of the specific capsular polysaccharide from the bacterium Rhizobium trifolii (TA)-1 has been shown to contain (a) terminal 4,6-O-(1-carboxyethylidene)-D-galactose (1 residue), (b) (1 → 3)-linked 4,6-O-(1-carboxyethylidene)-D-glucose (1 residue), (c) (1 → 4)-(1 → 6)-linked D-glucose (1 residue), (d) (1 → 4)-linked D-glucuronic acid (1 residue), and (e) (1 → 4)-linked D-glucose (4 residues). The pyruvylated sugars were shown to be positioned sequentially, and at least one other unit was interposed between them and the branch point.     

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

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.

     

Structural studies on an antitumor polysaccharide from Microellobosporia grisea

The structure of the antitumor polysaccharide from the actinomycete Microellobosporia grisea has been investigated. By methylation and periodate-oxidation studies, the polysaccharide was shown to consist of (nonreducing)d-mannosyl groups, (1→4)-linkedd-glucosyl residues, and 3,6-branched, (1→4)-linkedd-glucosyl residues in the approximate molar ratios of 2:1:1. Periodate oxidation of the polysaccharide, followed by borohydride reduction and mild hydrolysis with acid yielded glycerol, erythritol, 2-O-β-d-glucopyranosyl-d-erythritol, and 5-O-β-d-glucopyranosyl-2,4-bis(hydroxymethyl)-1,3-dioxane, which were isolated in the molar ratios of 2.0:0.14:0.74:0.35. Partial hydrolysis of the polysaccharide gave α-d-Man p-(1→6)-d-Glcp, β-d-Glcp-(1→4)-d-Glcp, α-d-Man p-(1→3)-d-Glcp, and β-d-Glcp-(1→4)-[α-d-Man p-(1→3)-]-d-Glcp. From these results, it is proposed that the polysaccharide is mainly composed of tetrasaccharide repeating-units having the following structure.     

Isolation and characterisation of the cell-wall fibres of carrot

Cell-wall fractions have been prepared from an alcohol-insoluble-residue of carrot root by treatment with (a) Pronase to remove the cytoplasmic proteins, (b) hot dilute acid and cold dilute alkali to give pectin-free residues, and (c) concentrated alkali to leave the α-cellulose and lignin. The purified cell-wall material still contained ∼ 1% protein and was composed mainly of cellulose, lignin, methyl-esterified galacturonic acid, and smaller amounts of galactose and arabinose. Methylation analysis of the insoluble residues indicated the presence, in order of decreasing concentration, of rhamnogalacturonan with the rhamnosyl residues carrying side chains at position 4, cellulose, (1→4)-linked galactan, (1→5)-linked arabinan, (1→4)-linked xylan, (1→4)-linked mannan, and xyloglucan.     

Oligosaccharides from “standardized intermediates”. The 2-amino-2-deoxy- d-galactose analog of the blood-group O(H) determinant,type 2, and its precursors

The selectively benzylated glycoside allyl 2-acetamido-4,6-di-O-benzyl-2-deoxy-β- d-galactopyranoside ( 4) was prepared from the corresponding derivative of 2-acetamido-2-deoxy- d-glucose via the p-bromobenzenesulfonate and the benzoate. 2-O-Benzoyl-3,4,6-tri-O-benzyl-α- d-galactopyranosyl chloride ( 10) was obtained from allyl 6-O-benzyl-2-O-(2-butenyl)-α- d-galactopyranoside via known intermediates. To complete the sequence, the 1-propenyl 3,4,6-tri-O-benzyl galactoside was successively converted into the 2-benzoate, the free sugar, and the chloride 10. A fully protected form ( 11) of the trisaccharide α- l-Fucp-(1→2)-β- d-Galp-(1→4)- d-GalNAc was then synthesized by coupling 10 to 4, partially deblocking the disaccharide product, and l-fucosylating the resulting intermediate. Cleavage of the O-benzyl groups from 11, with concomitant saturation of the allyl group, gave the propyl β-glycoside of the unsubstituted trisaccharide.     

The structure of the low molecular-weight glucans isolated from the siphonous green alga caulerpa simpliciuscula

A β-d-glucan of low molecular weight isolated from the marine alga Caulerpa simpliciuscula has been shown to contain 30 glucose residues. At least 27 of these are β-d-(1→3) linked. There are 1-2β-(1→6) branches per molecule, with a maximum of 4 d-glucose residues per side chain. As normally isolated, this glucan is associated with a soluble (1→4)-α-d-glucan (soluble starch) of the same molecular weight, in the ratio of 3 molecules of β-d-glucan per molecule of α-d-linked glucan.     

Structure of the d-galacto-d-mannan isolated from the seeds of Melilotus indica All

A d-galacto-d-mannan ([α]_D +72.0 and d-galactose-to-d-mannose ratio 1:1.14) was isolated from the seeds of Melilotus indica All., syn. M. parviflora Desf. The ¹H- and ¹³C-n.m.r., and i.r. spectra indicated the presence of α-d-galactopyranosyl and β-d-mannopyranosyl residues. Methylation of the polysaccharide, followed by hydrolysis, afforded, 2,3,4,6-tetra-, 2,3,6-tri-, 2,3-di-, and 3,4-di-O-methyl-d-mannose, and 2,3,4,6-tetra- and 2,3,6-tri-O-methyl-d-galactose in the molar ratios of 1:2:22:6:27:3. Periodate oxidation of the polysaccharide, followed by reduction and hydrolysis, gave erythritol (1 mol) and glycerol (1.24 mol). Partial acid hydrolysis of the polysaccharide afforded O-β-d-mannopyranosyl-(1→2)-d-mannopyranose, O-β-d-mannopyranosyl-(1→4)-d-mannopyranose, O-α-d-galactopyranosyl-(1→6)-d-mannopyranose, O-α-d-galactopyranosyl-(1→4)-d-galactopyranose, and O-α-d-galactopyranosyl-(1→6)-O-β-d-mannopyranosyl-(1→4)-d-mannopyranose. A highly branched structure having a mannan backbone composed of 36% of (1→4)- and 10% of (1→2)-linked β-d-mannopyranosyl units is proposed for the galactomannan.