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PubMed2001

Density-labelling of cell wall polysaccharides in cultured rose cells: comparison of incorporation of 2H and 13C from exogenous glucose.

Labelling with stable isotopes has under-exploited potential for studies of polysaccharide endotransglycosylation in vivo. Ideally, the labelled polysaccharides should have the highest possible buoyant density. Although [13C6]glucose has previously been used as a precursor, it was unclear whether 2H would be efficiently incorporated from [2H]glucose or lost as D2O. Rose (Rosa sp.) cell-suspension cultures efficiently incorporated 13C from D-[13C6,2H7]glucose into wall polysaccharides with negligible dilution from atmospheric 12CO2. Also, approximately 70% of the 2H atoms in D-[13C6,2H7]glucose were retained during polysaccharide biosynthesis. This shows that relatively few cycles of intermediary metabolism leading to the release of D2O occurred before sugar residues were incorporated into wall polysaccharides. In agreement with these observations, isopycnic centrifugation in caesium trifluoroacetate gradients showed that the hydrated buoyant density of xyloglucan synthesised by rose cells growing on [13C6,2H7]glucose and [13C6]glucose was 3.7 and 2.6% higher, respectively, than in isotopically non-labelled cultures. Thus, [13C,2H]glucose-feeding enabled a 42% better resolution of 'heavy' from 'light' xyloglucan than [13C]glucose-feeding.

Carbon Isotopes↗

PubMed2002

Structural analysis and chemical depolymerization of the capsular polysaccharide of Streptococcus pneumoniae type 1.

NMR spectroscopy can be used to characterize bacterial polysaccharides such as that of Streptococcus pneumoniae type 1 which is a component of the 23-valent pneumococcal vaccine in clinical use. This particular polysaccharide gives NMR spectra with wide lines apparently due to restricted molecular mobility and chain flexibility which leads to rapid dipolar T(2) relaxation limiting the possibility of detailed spectral analysis. Removal of O-acetyl groups found on approximately two thirds of the repeating subunits of pneumococcal type 1 capsule leads to narrower NMR lines facilitating a complete assignment of the 1H and 13C NMR spectra. Degradation of the polysaccharide by periodate oxidation followed by base treatment leads to an oligosaccharide fragment of approximately three repeating trisaccharide units. This oligosaccharide has narrow NMR lines and 1H and 13C assignments very similar to those of the O-deacetylated polysaccharide. In the native polysaccharide, O-acetyl groups are located on the 2- and 3-positions of the 4-linked galacturonic acid residue providing protection against periodate oxidation. Analysis of NOESY spectra combined with molecular modeling of the oligosaccharide shows that flexibility occurs in certain of the saccharide linkages.

Bacterial Vaccines↗

PubMed2002

Effect of roasting on degradation and structural features of polysaccharides in Arabica coffee beans.

The degree and nature of polysaccharide degradation at different roasting levels was determined for three Arabica (Coffea arabica) bean varieties. Between 12 and 40% of the bean polysaccharides were degraded depending on the roasting conditions. The thermal stability of the arabinogalactans, (galacto)mannans and cellulose was markedly different. The arabinogalactans and mannans were degraded up to 60 and 36%, respectively, after a dark roast, while cellulose showed negligible evidence of degradation. Roasting led to increased solubility of both the arabinogalactans and (galacto)mannans from the bean but the structural modifications, which accompanied this change in solubility, were different for each polysaccharide. Despite the moderate degradation of the (galacto)mannans, those remaining in the bean after roasting showed no evidence of change to their molecular weight even after a dark roast. In contrast, arabinogalactans were depolymerised after a light roast both by fission of the galactan backbone and loss of arabinose from the sidechains. The recently discovered covalent link between the coffee bean arabinogalactans and protein survived roasting. The glucuronic acid component of the AG was degraded markedly after a dark roast, but approximately 30% of the original content remained as part of the AG polymer. The results show that polysaccharide degradation during roasting is more marked than previously documented, and points to roasting induced changes to the polysaccharides as major factors in the changing physicochemical profile of the coffee bean during processing.

Carbohydrate Conformation↗

PubMed2002

Effect of (1-->3)- and (1-->4)-linkages of fully sulfated polysaccharides on their anticoagulant activity.

Chemically fully sulfated polysaccharides including xylan (-->4Xylbeta-(1-->4)Xylbeta1-->), amylose (-->4Glcalpha-(1-->4)Glcalpha1-->), cellulose (-->4Glcbeta-(1-->4)Glcbeta1-->), curdlan (-->3Glcbeta-(1-->3)Glcbeta1-->) and galactan (-->3Galbeta-(1-->3)Galbeta1-->), which have been isolated from Korean clam, were prepared, and their anticoagulant activity was investigated. The results strongly suggest that the activity might not be depending on anomeric configuration (alpha or beta) or monosaccharide species but on the glycosidic linkage, either (1-->3) or (1-->4). 1H NMR studies of these modified polysaccharides show that the neighboring sulfate groups at the C-2 and C-3 positions might have caused the conformational changes of each monosaccharide from 4C(1) to 1C(4). Furthermore, the effect of 6-sulfate residues on the anticoagulant activity was investigated using a specific desulfated reaction for the chemically fully sulfated polysaccharides. The 6-sulfate group is very important in determining anticoagulant activity of (1-->3)-linked polysaccharides, whereas the activity is not affected by presence or absence of the 6-sulfate group in (1-->4)-linked polysaccharides.

Alcaligenes↗

PubMed1996

Structure of the O-specific polysaccharide of Hafnia alvei PCM 1222 containing 2-aminoethyl phosphate.

The O-specific polysaccharide of H. alvei strain PCM 1222 has a branched hexasaccharide repeating unit containing D-galactose, L-rhamnose, D-ribose, D-galacturonic acid, and 2-acetamido-2-deoxy-D-glucose in the ratios 1:2:1:1:1, as well as 2-aminoethyl phosphate (EtNP) and O-acetyl groups in nonstoichiometric amounts. The polysaccharide was modified by carboxyl reduction, O-deacetylation, and dephosphorylation with 48% hydrofluoric acid, the last reaction being accompanied by removal of the lateral residue of beta-galactofuranose. The modified polysaccharides were studied by methylation analysis and 1H and 13C NMR spectroscopy, including 2D correlation spectroscopy (COSY), H-detected 1H,13C and 1H,31P heteronuclear multiple-quantum coherence (HMQC), 1D NOE, 2D rotating-frame NOE spectroscopy (ROESY), and 2D combined total correlation spectroscopy (TOCSY) and ROESY (TORO). The following structure of the O-deacetylated polysaccharide was established: [formula: see text] In different batches of the polysaccharide, the content of EtNP varied from 0.35 to 0.55 and that of the O-acetyl groups from 0.05 to 0.4 per repeating unit. It was tentatively suggested that the O-acetyl group is located at position 4 of a rhamnosyl residue.

Aminoethylphosphonic Acid↗

PubMed1987

A highly specific two-site ELISA for pneumococcal C-polysaccharide using monoclonal and affinity-purified polyclonal antibodies.

A two-site ELISA for the detection of pneumococcal C-polysaccharide (PnC) has been developed. A monoclonal antibody directed against the phosphorylcholine residue of the PnC was used as catcher and an affinity-purified polyclonal anti-PnC rabbit antiserum for detection. Polyclonal antibodies against the PnC as well as capsular antigens were obtained by immunizing rabbits with type 1 pneumococci. Antibodies against the phosphorylcholine determinant of PnC could be removed by affinity purification. Remaining antibodies reacted in an ELISA with type 1 capsular polysaccharide as well as with PnC. Only in the fraction with the highest antibody activity against PnC, phosphorylcholine exhibited a slight inhibitory action. It is concluded that the purified antibody preparation reacted with an antigenic determinant shared by the two polysaccharides, in all probability a determinant associated with 2-acetamido-4-amino-2,4,6-trideoxygalactose which is the only monosaccharide component in common between PnC and the type 1 capsular polysaccharide. By the use of this affinity-purified antibody preparation, reactions with alpha-streptococci, occurring with non-purified serum, were abolished. The sensitivity and specificity of the test was determined using capsulated and non-capsulated pneumococci and alpha-streptococci known to cross-react with unpurified serum against the pneumococcal C-polysaccharide.

Animals↗

PubMed1996

Total and functional antibody response to a quadrivalent meningococcal polysaccharide vaccine among children.

OBJECTIVE: To determine total and functional serogroup C antibody response after vaccination with a quadrivalent meningococcal polysaccharide vaccine. DESIGN: Prospective, before and after intervention study. SUBJECTS: Study subjects were between the ages of 0.5 and 19.9 years, and were eligible for a community-wide public health immunization campaign against Neisseria meningitidis serogroup C. METHODS: Total and functional antibody response was measured by enzyme-linked immunosorbent assay and bactericidal assay, respectively. RESULTS: One month after vaccination, total capsular polysaccharide antibody significantly increased in all age groups; a significant rise in bactericidal antibody, that correlated with total capsular polysaccharide antibody, was seen in children 18 months of age and older. At 1 year bactericidal antibody titers were maintained but capsular polysaccharide antibody declined substantially in children younger than 5 years. CONCLUSION: Total capsular polysaccharide antibody concentration appears to be a useful surrogate measure of bactericidal antibody in children 18 months and older. Children who originally received the vaccine at less than 18 months of age should be considered for revaccination if there is a new or continuing risk of disease. Because of the differences in the total and bactericidal antibodies formed, vaccine efficacy trials are required to define which serologic measures are associated with protection.

Adolescent↗

PubMed1983

Visualization of bacterial polysaccharides by scanning transmission electron microscopy.

Highly purified capsular polysaccharides of Neisseria meningitidis groups A, B, and C have been visualized by high resolution Scanning Transmission Electron Microscopy (STEM). Spheroidal macromolecules approximately 200 A in diameter are characteristic of the Meningococcus A and C polysaccharides whereas filaments that are 400-600 A in length are found in Meningococcus B polysaccharide preparations. Filaments are occasionally found associated with the spheroidal Meningococcus A and C polysaccharides and it is proposed that these structures are composed of a long (1-4 microns) filament or filaments that are arranged in spheroidal molecules or micelles of high molecular weight. The Meningococcus B polysaccharide, by contrast, is a short flexuous filament or strand of relatively low molecular weight. A relationship between morphology and antigenicity is proposed.

Freeze Drying↗

PubMed2002

Structural studies of the pectic polysaccharide from duckweed Lemna minor L.

The pectic polysaccharide of duckweed Lemna minor L. termed lemnan (LM) was shown to contain the ramified, "hairy" region. Using partial acid hydrolysis and Smith degradation followed by NMR spectroscopy of the fragments obtained, some structural features of the hairy region of LM were elucidated. Partial acid hydrolysis of LM afforded the crude polysaccharide fraction LMH that was separated into two polysaccharide fractions: LMH-1 and LMH-2. In addition, the oligosaccharide fraction LMH-3 contained 97% D-apiose was obtained from the supernatant. A further more rigorous acidic hydrolysis of LMH led to the crude polysaccharide fraction LMHR which was separated in to two fractions: LMHR-1 and LMHR-2. Smith degradation of LMH afforded the polysaccharide fragment LMHS differed in low contents of apiose residues. Unfortunately, NMR-spectroscopy failed to provide significant evidence concerning the structure of LMH-1 due to the complexity of the macromolecule. The structure of the 1H/13C-NMR spectroscopy including the correlation 2D NMR spectroscopy. As a result, alpha-1,4-D-galactopyranosyluronan was confirmed to be the main constituent of the LM backbone. In addition, the ramified, "hairy" region of the macromolecule appeared to contain segments consisting of residues of terminal and beta-1,5-linked apiofuranose, terminal and alpha-1,5-linked arabinofuranose, terminal and beta-1,3- and beta-1,4- linked galactopyranose, the terminal and beta-1,4-linked xylopyranose, and beta-1,4-linked 2-mono-O-methyl xylopyranose. Analytical and NMR-spectral data of LMHS confirmed the presence of considerable amounts of the non-oxidized of 1,4-linked D-galactopyranosyl uronic acid residues. Thus, some side chains of the ramified region of lemnan appeared to attach to D-galactopyranosyl uronic acid residues of the backbone.

Chromatography↗

PubMed1995

Isolation and structural characterization of adhesin polysaccharide receptors.

The procedure for the purification of the adhesin polysaccharide receptor and its hexasaccharide repeating unit from whole S. oralis ATCC 55229 by chemical, enzymatic, and chromatographic techniques has been described. Chemical, chromatographic, and mass spectrometric procedures allow preliminary structural characterization of the hexasaccharide repeating unit and polysaccharide. The structural characterizations of the hexasaccharide and polysaccharide are completed using several 1D and 2D NMR techniques. Identification of the anomeric 1H and 13C signals of the glycosyl residues permits, by virtue of their chemical shifts and coupling constants (3JHH and 1JCH), the determination of the configurations of the glycosidic linkages. The HMBC connectivities permit the establishment of the hexasaccharide sequence as Rhap alpha(1-->2)Rhap alpha(1-->3)Galp alpha(1-->3)Galp beta(1-->4)Glcp beta(1-->3)Gal. The 1H NMR chemical shifts of the polysaccharide, as determined by the combination of COSY and TOCSY experiments, and the observed interglycosidic NOESY cross-peaks reveal the structure of the polysaccharide to be [formula: see text] where the position of the glycerol (Gro) phosphate moiety has been determined by [1H, 31P] NMR spectroscopy.

Adhesins, Bacterial↗

PubMed1998

Effect of immunosuppression after cardiac transplantation in early childhood on antibody response to polysaccharide antigen.

BACKGROUND: Three children who had cardiac transplantation before age 4 years later presented with recurrent sinopulmonary infection caused by organisms including Streptococcus pneumoniae, in which capsular polysaccharide plays an important part, one developed bronchiectasis. We therefore studied responses to polysaccharide antigen after immunosuppression started in early childhood. METHODS: Antibodies against pneumococcal and haemophilus polysaccharides, and total IgG, IgG1, IgG2, and IgA concentrations were measured in 33 cardiac-transplant recipients transplanted before the age 4 years (group 1) and after that age (group 2). Patients with low pneumococcal and haemophilus antibody concentrations were immunised with 23 polyvalent pneumococcal and tetanus-haemophilus conjugate vaccines and antibody responses were measured. FINDINGS: Five patients from group 1 and seven from group 2 were transplanted for congenital heart disease and ten patients in each group had heart transplants because of cardiomyopathy; none were asplenic. Group 1 (16 patients) were aged 2-10 years when investigated, group 2 (17 patients), were 6-16 years. Four of 16 patients in group 1 responded to pneumococcal polysaccharide vaccine compared with 14 of 17 in group 2 (p=0.0016). This difference remained when those in group 1, aged less than 4 years at investigation, were excluded (p=0.0060). Response to haemophilus-conjugate vaccine was similar in both groups (14 of 16 vs 14 of 17, p=1.0). Significantly more patients who failed to respond to pneumococcal vaccine had low IgG2 concentrations (p=0.0269). INTERPRETATION: Children who had a transplantation and immunosuppression in early childhood before they had developed antibody responses to pneumococcal polysaccharide, still failed to show a response when older-ie, when such responses are the norm. Ongoing immunosuppression prevents the maturation of antipolysaccharide responses leaving children susceptible to severe and recurrent damaging infection.

Aging↗

PubMed2001

Crystallinity and polysaccharide chains of beta-glucan in white sorghum, SK(5912).

The polysaccharide chains and the crystallinity of beta-glucan in a white sorghum variety, SK(5912) were investigated using chemical and enzymic studies. Mild periodate oxidation and methylation, coupled to descending paper chromatography of products revealed the presence of unresolved non-carbohydrate moiety, 2, 4-and 2, 3-di-O-methyl D-glucose residues (molar ratio; 18:3) and 2, 4, 6-and 2, 3, 6-tri-O-methyl D-glucose residues (molar ratio; 1:14). Paper chromatography of the total acid hydrolysate also revealed a non-carbohydrate spot, identified as protein on the basis of positive Biuret and ninhydrin tests. The O-methyl D-glucose residues suggest two polysaccharide chains designated X and Y. Chain X is formed through linking of beta-D-glucopyranosyl residues by (1-->3) linkages with 85-86% (1-->6) bonds at branch points and constitute about 6-7% of the beta-glucan sample. Chain Y, which is 93-94% of the beta-glucan polysaccharide chains, constitutes beta-D-glucopyranosyl residues in (1-->4) linkages and 4-5% (1-->6) bonds at branch points. Of the 18 branch points on the X-chains in a given beta-glucan sample, about 15 are the Y chains interlinked to the X-chains through their (Y-chains) reducing ends. Both acid and enzyme hydrolyses of the beta-glucan suggest two structural organizations, a crystalline and less crystalline granules, based on two first order kinetics. This was correlated by the progress curves obtained during hydrolysis with two purified isoforms of beta-glucanases from the sorghum malt. The short and highly branched polysaccharide chains, and longer but less branched polysaccharide chains found in this beta-glucan are reminiscent of the structures of amylopectin and amylose, respectively. The K(m)s of 0.30-0.32 and 0.42-0.50 mg beta-glucan/ml for the beta-glucanase isoforms also lay credence to both the crystalline forms and the highly polymerised nature of the beta-glucan in white sorghum.

Crystallization↗

PubMed1997

Structural studies of CV-70 polysaccharide.

The goal of this paper is the characterization of the chemical structure of the water-soluble polysaccharide, CV-70, produced by bacteria Beijerinckia sp. Beijerinckia sp. is a genus of gram-negative, aerobic bacteria, usually found in sugar cane root. The CV-70 polysaccharide was produced in a fermentation medium containing 5% sucrose as the carbon source, tryptose and salts, at 25 degrees C [1]. The polysaccharide was hydrolyzed with 2 N trifluoroacetic acid at 100 degrees C for 16 h, purified, and analyzed by HPLC. Index of refraction was used for the detection of sugars. For GC-MS analysis, the CV-70 polysaccharide was derivatized through methylation and acetylation. Together with the GC-MS data, periodate oxidation studies were used to determine the possible glucosidic linkages. Carbon-13 NMR studies were carried out with hydrolyzed and silylated samples. Glucose, galactose and fucose were identified as the components in the CV-70 polysaccharide, in a 3:1:3 ratio.

Bacteria↗

PubMed1999

Molecular basis for the lack of mimicry of Brucella polysaccharide antigens by Ab2gamma antibodies.

The crystal structure of the complex of an anti-Id Fab with an Fab specific for a Brucella polysaccharide antigen has previously been reported (Evans et al., 1994, J. Mol. Biol. 241, 691-705). To complement this study, the binding characteristics and immunological properties of this Ab2 and two others raised with a second anti-Brucella antibody were investigated, including quantitative kinetic measurements by surface plasmon resonance. The affinities of the Fabs from the Ab2s for the Ab1s were three orders of magnitude greater than those estimated for the antigen, but the Ab2s failed to induce antigen-binding Ab3s, that is, they were of the Ab2gamma type. The avidities of the Ab1s for antigen were however within one order of magnitude of their avidities for Ab2. Tests of 16 other anti-Brucella polysaccharide antibodies showed that the two idiotopes were not present in them, and in confirmation of the lack of a dominant idiotope, N-terminal sequencing of their H and L chains showed a wide variety of V genes were employed in the immune response to the Brucella polysaccharides. The failure of the Ab2 to induce antigen-reactive Ab3 thus appears to be due to neither intrinsic affinity nor idiotope frequency, but arises instead from structural reasons, for example, the incomplete penetration of the Ab2 into the binding-site cleft of the Ab1. The surface topography of polysaccharide antigens and their binding-sites thus appears to be especially difficult for Ab2s to mimic and will restrict their routine use as surrogates for T-cell independent polysaccharide antigens.

Amino Acid Sequence↗

PubMed1997

The isolation and characterization of an immunomodulatory and anti-tumor polysaccharide preparation from Flammulina velutipes.

Alkaline-soluble antitumor polysaccharide was prepared from the cell wall of the mushroom Flammulina velutipes. The backbones) of the polysaccharide is mainly composed of beta-(1-->3)-D-linked glucose and its molecular weight was estimated to be about 200 kD. The polysaccharide was found to be non-toxic by brine shrimp assay. When injected into mice intraperitoneally, the polysaccharide triggered proliferation of splenic lymphocytes and also vascular dilation and hemorrhage (VDH) response. The polysaccharide exhibited potent anti-tumor activity against sarcoma SC-180 in vivo but not in vitro.

Adjuvants, Immunologic↗

PubMed2002

Sulfation of extracellular polysaccharides of red microalgae: preparation, characterization and properties.

Polysaccharides are natural polymers with a variety of properties that may be translated into significant commercial applications. A program of chemical modifications of the extracellular polysaccharides of red microalgae, such as Porphyridium sp. and Rhodella reticulata, has been undertaken by our group in order to tailor new properties and hence to broaden the spectrum of potential applications. These algal biopolymers are anionic in nature due to the presence of uronic acids (about 10%) and sulfate half esters (about 7%). In the current study, the sulfate content of these biopolymers was increased to 35-40% by means of sulfation agents such as pyridine SO(3), DMF.SO(3) and ClSO(3)H. Reaction conditions were optimized in a model system based on potato starch as the model polysaccharide (type of reagent, temperature and time of reaction). After work-up procedures, the highest sulfate content was obtained by sulfation of the polysaccharide of Porphyridium sp. with a mixture of ClSO(3)H and pyridine at 70 degrees C for 1 h. The sulfated products were characterized by chemical and rheological analyses, IR spectroscopy, and GPC-HPLC chromatography. "Oversulfated" polymers (having sulfate contents exceeding 20%) with high molecular weights were found to inhibit mammalian cell growth when used at certain concentrations; for example, over 80% inhibition was obtained when oversulfated polymers at a concentration of 200 microg/ml were tested on T-cell lymphoma line 24-1. These preliminary results indicate that the modified polysaccharides do indeed exhibit potential therapeutic properties.

Biopolymers↗

PubMed2002

Activity of Porphyridium sp. polysaccharide against herpes simplex viruses in vitro and in vivo.

The cell wall sulfated polysaccharide of the red microalga Porphyridium sp. exhibited impressive antiviral activity against herpes simplex virus types 1 and 2 (HSV-1 and -2) both in vitro (cell culture) and in vivo (rats and rabbits). Depending on the concentration, this polysaccharide completely inhibited or slowed down the development of the cytopathic effect in HSV-infected cells, but did not show any cytotoxic effects on vero cells even when a concentration as high as 250 microg/ml was used. There was indirect evidence for a strong interaction between the polysaccharide and HSV and a weak interaction with the cell surface. When tested in vivo, Porphyridium sp. polysaccharide conferred significant and efficient protection against HSV-1 infection: at a concentration as low as 100 microg/ml, it prevented the appearance and development of symptoms of HSV-1 infection in rats and rabbits. The polysaccharide did not exhibit any cytotoxic effects at a concentration of 2 mg/ml in vivo.

Adsorption↗

PubMed2003

Submerged cultivation of Ganoderma lucidum biomass and immunostimulatory effects of fungal polysaccharides.

Original Ganoderma lucidum strain MZKI G97 isolated from Slovenian forests was cultivated in a liquid substrate based on potato dextrose and olive oil. The influences of inoculum and oxygen partial pressure in batch and fed batch cultivation in a 10-l laboratory stirred tank reactor were studied. Fungal biomass was found to be oxygen and shear sensible. Using a 17% (wet weight) 6 days old vegetative inoculum, 9.6 g l(-1) of dry biomass in batch cultivation and 15.2 g l(-1) in fed batch process were obtained. Extracellular (9.6 g l(-1)) and intracellular (6.3 g l(-1)) polysaccharide fractions were isolated. Extracellular polysaccharide fraction and four intracellular polysaccharide fractions were obtained. Polysaccharides were further separated by ion-exchange, gel and affinity chromatography. The isolated polysaccharides were mainly beta-D-glucanes. Immunostimulatory effects of isolates were tested on induction of cytokine (tumour necrosis factor alpha (TNF-alpha) and interferon gamma (IFN-gamma)) synthesis in primary cultures of human peripheral blood mononuclear cells (PBMC) isolated from a buffy coat. The TNF-alpha inducing activity is comparable with romurtide, which has been used as a supporting therapy in cancer patients treated with radiotherapy and/or chemotherapy.

Biomass↗