Structural studies of the Rhizobium trifolii extracellular polysaccharide

The structure of the extracellular polysaccharide of Rhizobium trifolii has been investigated. Methylation analysis, sequential degradations by oxidation and elimination of oxidized residues, uronic acid degradation, and degradation by oxidation of the acetylated polysaccharide with chromium trioxide in acetic acid were the main methods used. It is proposed that the polysaccharide is composed of heptasaccharide repeating-units having the following structure:

An unusual feature is that some of the repeating units are incomplete and lack the terminal β-d-galactopyranosyl group. The polysaccharide contains O-acetyl groups (somewhat more than 1 mol. per unit), linked to O-2 and O-3 of 4-O-substituted d-glucopyranosyl chain-residues. A previous finding that the polysaccharide contains 2-deoxy-d-arabino-hexose (2-deoxy-d-glucose) residues is erroneous.     

Structural studies on Klebsiella type 61 capsular polysaccharide

The capsular polysaccharide from klebsiella type 61 was found to contain d-galactose, d-glucose, d-mannose, and d-glucuronic acid in the ratios 1:2:1:1. Acid hydrolysis of the polysaccharide gave one aldobiouronic acid, whose structure was established. Methylation analysis of the polysaccharide provided information about the linkages in the polysaccharide. The polysaccharide is composed of a pentasaccharide repeating unit for which structures are proposed.     

Effect of flavonoids on the composition of surface glycopolymers of Azospirillum lipoferum Sp59b

Cultivation of the type strain Azospirillum lipoferum Sp59b in the presence of flavonoid quercetin induced modification of the structure of the bacterial lipopolysaccharide. Cultivation in the presence of the flavonoid was shown to result in altered serological characteristics of the bacteria, increased heterogeneity of the outer membrane lipopolysaccharide pool, as well as in modified composition and fatty acid ratio of lipid A. The flavonoid was shown to induce the synthesis of the O-specific polysaccharide with the repeating structure represented by a tetrasaccharide consisting of a linear trisaccharide fragment of α-L-Rhap residues in the main chain and the terminal β-D-Glcp residue. The structure of this O-specific polysaccharide was identical to the previously determined structure of the capsular polysaccharide of these bacteria grown without quercetin. Modifications in the structural composition of the capsular polysaccharide induced by cultivation in the presence of quercetin were revealed.     

Structural studies of the capsular polysaccharide of Klebsiella type 52

The structure of the capsular polysaccharide from Klebsiella Type 52 has been investigated. Methylation analysis, characterization by gas-liquid chromatography-mass spectrometry of oligosaccharide derivatives obtained on partial hydrolysis of the methylated polysaccharide with acid, and specific degradation of the methylated polysaccharide by successive treatments with base and acid followed by characterization of the product, were the principal methods used. The polysaccharide is composed of hexasaccharide repeating-units containing D-glucuronic acid, D-galactose, and L-rhamnose, in the ratios 1:3:2. A structure for these units, disregarding the anomeric natures of the sugar residues, is proposed.     

Structure of the capsular polysaccharide of Klebsiella K- type 63

Structural investigation of the capsular polysaccharide from Klebsiella K type 63 by methylation analysis, periodate oxidation, and uronic acid degradation showed the repeating unit to consist of →3)-α-D-Galp-(1→3)-α-D-GalpA-(1→3)-α-L-Fucp(1→. This structure is identical to that of Escherichia coli serotype K-42 capsular polysaccharide. The ¹H- and¹³C-n.m.r. spectra of the original and modified polysaccharide are consistent with the foregoing structure.     

Structural studies on a new polysaccharide,containing d-riburonic acid,from Rhizobium meliloti IFO 13336

The structure of an extracellular, acidic polysaccharide from Rhizobium meliloti IFO 13336 was studied by a method involving successive fragmentation with specific β-d-glycanases of Flavobacterium M64. The polysaccharide is composed of repeating units of the octasaccharide shown. An acidic component was identified as d-riburonic acid.     

Polysaccharide structure of tetrasporic red seaweed Tichocarpus crinitus

Sulfated polysaccharide isolated from tetrasporic plants of Tichocarpus crinitus was investigated. The polysaccharide was isolated by two methods: with water extraction at 80 °C (HT) and with a mild alkaline extraction (AE). The extracted polysaccharides were presented by non-gelling ones only, while galactose and 3,6-AG were the main monosaccharides, at the same time amount of 3,6-AG in AE polysaccharides was the similar to that of HT. According to methods of spectroscopy and mass spectrometry, the polysaccharide from tetrasporic T. crinitus contains main blocks of 1,3-linked β-d-galactopyranosyl-2,4-disulfates and 1,4-linked 3,6-anhydro-α-d-galactopyranosyl while 6-sulfated 4-linked galactopyranosyl resudies are randomly distributed along the polysaccharide chain. The alkaline treatment of HT polysaccharide results in obtaining polysaccharide with regular structure that composed of alternating 1,3-linked β-d-galactopyranosyl-2,4-disulfates and 1,4-linked 3,6-anhydro-α-d-galactopyranosyl residues. Native polysaccharide (HT) possessed both high anticoagulant and antiplatelet activity measured by fibrin clotting and platelet aggregation induced by collagen. This activity could be connected with peculiar chemical structure of HT polysaccharide which has high sulfation degree and contains also 3,6-anhydrogalactose in the polymer chain.     

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.     

Structural studies of the capsular polysaccharide of Klebsiella type 37

The structure of the Klebsiella type 37 capsular polysaccharide has been investigated. Methylation analysis, various specific degradations, and n.m.r. spectroscopy were the principal methods used. It is concluded that the polysaccharide is composed of tetrasaccharide repeating-units having the structure 4-O-Lac-d-GlcA  4-O-[(S)-1-carboxyethyl]-d-glucuronic acid:

     

Reactions between diglycolaldehyde dithioacetals and some nucleophiles

The homogeneous, neutral polysaccharide isolated from the crude polysaccharide of the fruit pulp from bael (Aegle marmelos) contains arabinose, galactose, and glucose in the molar ratios of 2:3:14. The linkages among the different monosaccharide residues were established through methylation analysis and Smith-degradation studies of the polysaccharide. The anomeric configurations of the different glycosyl groups were determined by study of the chromium trioxide oxidation of the acetylated polysaccharide. Results of these experiments have been discussed in order to assess the structure of the neutral polysaccharide.     

Structural studies on the soluble polysaccharide from Iridaea membranacea

Aqueous extraction of the red alga Iridaea membranacea gave a high-sulfated polysaccharide. The structure of the polysaccharide has been investigated by hydrolysis, methanolysis, and fractionation. It resembles carrageenan in composition, but fractionation with KCl, and methylation analysis of two homogeneous fractions, showed that it is a complex mixture of sulfated d-galactans.     

Structural studies of gellan gum,an extracellular polysaccharide elaborated by Pseudomonas elodea

The structure of gellan gum, a polysaccharide of potential commercial usefulness elaborated by Pseudomonas elodea, has been investigated. It is concluded that the polysaccharide is composed of tetrasaccharide repeating-units having the following structure.

Of the repeating units, ～25% contain an O-acetyl group linked to C-6 of one of the β-d-glucopyranosyl residues.     

A chitin sulfate-like polysaccharide from the test of the tunicate Halocynthia roretzi

Considerable amounts of water-soluble polysaccharides were found in the test of the tunicate Halocynthia roretzi. After fractionation with ethanol, a chitin sulfate-like polysaccharide was isolated. From the results of chemical analysis, optical rotation, infrared spectrum and alkaline treatment, it is suggested that the predominant structure for this polysaccharide is (1→4)-2-acetamido-2-deoxy-6-O-sulfo-β-D-glucopyranan.     

Production and properties of glycogen in the marine obligate chemolithoautotroph,Hydrogenovibrio marinus

Production of an intracellular polysaccharide was observed during cultivation of a marine, obligately chemolithoautotrophic hydrogen-oxidizing bacterium, Hydrogenovibrio marinus, under nitrogen or magnesium starvation or oxygen limitation in a continuous gas supply. The polysaccharide formed in oxygen-limited cells was isolated and shown to be composed of only glucose. Instrumental and enzymatic analyses revealed that the polysaccharide has a glycogen-like structure.     

Spectroscopic characterisation of order-disorder transitions for extracellular polysaccharides of arthrobacter species

The conformational behaviour of the extracellular polysaccharides from Arthrobacter species of soil-borne bacteria has been investigated by nuclear magnetic resonance relaxation and optical rotation. Polysaccharides from A. stabilis, A. viscosus, and A. viscosus sp. n, in solution at room temperature, all show evidence of an ordered conformation which can be melted out on heating. The temperature course of this transition, however, shows considerable variation with bacterial species. Thus A. stabilis polysaccharide shows a very sharp conformational transition centred around 60°, whereas the transitions of the polysaccharides from both strains of A. viscosus occur over a much broader temperature-range. The transition for the polysaccharide of A. viscosus sp. n is again centred close to 60°, whereas, for A. viscosus, melting of the tertiary structure of the polysaccharide is incomplete at 100°. O-Deacetylation destroys the ordered conformation of both A. viscosus polysaccharides. The ordered structure of A. stabilis polysaccharide, by contrast, is stabilised by removal of acyl substituents (which here include succinic half-ester). Understanding of the conformational state of these materials affords considerable insight into their gelation behaviour and unusual solution rheology. The known solution interactions with certain plant polysaccharides suggest a possible biological role for Arthrobacter polysaccharides in relationships with components of plant root-systems.     

Ultrastructural observations on Barroussia schneideri (apicomplexa,eucoccidiida) in the centipede Lithobius forficatus

The ultrastructure of the principal stages of Barroussia schneideri in the intestinal cells of the centipede, Lithobius forficatus, is described. The structure of the merozoites has much in common with that of other Eimeriidae: pellicle of an outer and two inner membranes, microtubules, mitochondria, micronemes, rhoptries, endoplasmic reticulum, and polysaccharide granules. The mature macrogamete has a large nucleus with a distinct nucleolus, wall-forming bodies of type 1 (WFB1), and presumably of type 2 (WFB2), and a large number of polysaccharide granules. The microgametocyte includes smaller polysaccharide granules closely associated with the cisternae of the endoplasmic reticulum. The microgametocyte surface is smooth in outline and has peripherally arranged nuclei. Microgametes have a curved nucleus, a mitochondrion, polysaccharide granules, and two flagella. One of the flagella is attached for some distance along the body.     

Structural studies of the polysaccharide antigen of Eubacterium saburreum, Strain L 32

The structure of the polysaccharide antigen produced by Eubacterium saburreum, strain L 32, has been investigated. The principal methods used were methylation analysis, graded hydrolysis with acid, and n.m.r. spectroscopy. The polysaccharide, which contains the unusual sugar 3,6-dideoxy-D-arabino-hexose (tyvelose, Tyv), is composed of trisaccharide repeating-units having the following structure:

     

Structural studies of the capsular polysaccharide elaborated by Haemophilus influenzae type d

The structure of the capsular polysaccharide elaborated by Haemophilus influenzae type d has been investigated, methylation analysis and n.m.r. spectrometry being the principal methods used. It is concluded that the polysaccharide is composed of repeating units having the structure: →4)-β-d-GlcpNAc-(1→3)-β-d-ManpNAcA-(1→. In addition, single residues of l-alanine, l-serine, or l-threonine, in the proportions 2:2:1, are linked, through their amino groups, to C-6 of the 2-acetamido-2-deoxy-β-d-mannopyranosyluronic acid residues. The degree of substitution (75-85%) varies for different preparations.     

Structural studies of an extracellular polysaccharide (S-198) elaborated by Alcaligenes ATCC 31853

The structure of an extracellular polysaccharide, S-198, elaborated by Alcaligenes ATCC 31853 has been investigated; methylation analysis, specific degradations, and ¹H-n.m.r. spectroscopy were the main methods used. It is suggested that the polysaccharide is composed of “repeating units” with the structure

A sugar residue in the chain may be either L-rhamnose or L-mannose and only ≈50% of the residues contain the branching α-L-rhamnopyranosyl group. The polysaccharide further contains O-acryl groups. It belongs to a group of polysaccharides, elaborated by Alcaligenes and Pseudomonas species, which all have the same linear backbone (except that some of them do not contain L-mannose) without branching or with branches that differ in their chemical structures and/or positions.     

Glycosylation by d-fructofuranose thio-orthoesters

The capsular polysaccharide from Klebsiella type K54, containing both O-formyl and O-acetyl groups, has been investigated by using the techniques of methylation analysis (by gas-liquid chromatography), periodate oxidation-Smith degradation, and both ¹H- and ¹³C-n.m.r. spectroscopy. Degradation of the native polysaccharide with a bacteriophage-induced glucosidase generated a formylated, as well as a formylated and acetylated, tetrasaccharide, whereas similar depolymerization of the deacetylated polysaccharide yielded a single tetrasaccharide; the corresponding, O-acylated octasaccharides were also isolated and characterized. These oligosaccharides, utilized in chemical and spectroscopic studies in order to determine the location of the O-acyl substituents in the repeating sequence, indicated formylation at O-4 of each lateral d-glucosyl group and acetylation at O-2 of alternate l-fucosyl residues. A new structure for the repeating unit in the polysaccharide is proposed.