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PubMed1976

An anti-A-like lectin of Rana catesbiana eggs showing unusual reactivity.

A lectin was isolated from Rana catesbiana eggs that agglutinated blood group A-erythrocytes but did not agglutinate blood group B- or 0-erythrocytes. The lectin was purified by Sephadex G-75 gel filtration and by acrylamide gel electrophoresis at pH 4.3 and was proved to be homogeneous on electrophoresis, and the molecular weight was determined as 210 000. The specificity of A-like activity seems to direct towards three monosaccharide units: GalNAcalpha1 leads to 3(or 4)-Galbeta1 leads to 4(or 3)GlcNAcbeta1 leads to R based on inhibition of A-like hemagglutination by various monosaccharides, oligosaccharides and glycolipids, and based on precipitin reaction with various glycolipids and glycoproteins with known structures. Uniquely, A-like agglutination was inhibited not only by alpha-N-acetylgalactosamine analogs but also by N-acetyllactosamine analogs. The lectin showed therefore, two correlated specificities: one directed towards alpha-N-acetylgalactosamine residue at the terminal, and the other towards the subterminal Galbeta1 leads to 4betaGlcNAc (N-acetyllactosaminyl) residue. The reactivity due to the N-acetyllactosamine structure which is also found in erythrocyte ganglioside and in H-active chain might be blocked by sialyl or alpha-L-fucosyl substitution at the terminal, as the reactivity appeared after elimination of these sugar residues. In the A structure the reactivity due to N-acetyllactosaminyl residue seems not to be blocked by the presence of alpha-N-acetylgalactosamine at the terminal as A-agglutination was strongly inhibited by N-acetyllactosamine and its analogs. Although the lectin showed a single band on electrophoresis under different conditions, there is a possibility that the lectin may be a mixture of two proteins with different specificities as mentioned above.

ABO Blood-Group System↗
PubMed1991

Comparison of carbohydrate substrate preferences in eight species of bifidobacteria.

Eight species of bifidobacteria were tested for their abilities to grow on a range of monosaccharides (glucose, arabinose, xylose, galactose and mannose). In contrast to the other sugars, glucose and galactose were utilized by all species and, in general, specific growth rates were highest on these sugars. Different substrate preferences were observed between species when the bacteria were grown in the presence of all five monosaccharides. For example, glucose and xylose were coutilized by Bifidobacterium longum, whereas glucose repressed uptake of all other sugars in B. bifidum and B. catenulatum. Galactose was the preferred substrate with B. pseudolongum. In B. angulatum, glucose and galactose were utilized simultaneously. B. breve did not grow on arabinose when this sugar provided the sole source of energy. However, glucose and arabinose were preferentially taken up during growth on sugar mixtures.

Arabinose↗
PubMed1993

Changes in glycosylation of L1210 cells after exposure to various antimetabolites.

This study establishes that antimetabolites do have the potency to change cellular glycosylation, as was suggested in our previous review (Eur J Cancer 1990, 26, 516-523). Murine leukaemia L1210 cells were exposed to various antimetabolites under non-lethal conditions. The antimetabolites 5-fluorouracil (5FU), arabinofuranosylcytosine (AraC), methotrexate (MTX) and 6-mercaptopurine (6MP), but not 6-thioguanine, induced considerable changes in the metabolic incorporation of radioactively labelled monosaccharides. Each antimetabolite exhibited a different effect. Significant differences were found between the radioactivity incorporated from the monosaccharides glucosamine, fucose, mannose and galactose, relative to control values. Polyacrylamide gel electrophoresis indicated that changes were induced in the glycosylation of individual glycoproteins. 5FU, AraC, MTX and 6MP all influenced both pyrimidine- and purine-mediated sugar incorporation. This excludes, therefore, direct effects of the antimetabolites on their analogue nucleotide-sugars. The antimetabolite-induced changes in glycosylation did not directly correlate with the observed cell-cycle effects of the antimetabolites.

Animals↗
PubMed2003

Structure of bacterial lipopolysaccharides.

Bacterial lipopolysaccharides are the major components of the outer surface of Gram-negative bacteria They are often of interest in medicine for their immunomodulatory properties. In small amounts they can be beneficial, but in larger amounts they may cause endotoxic shock. Although they share a common architecture, their structural details exert a strong influence on their activity. These molecules comprise: a lipid moiety, called lipid A, which is considered to be the endotoxic component, a glycosidic part consisting of a core of approximately 10 monosaccharides and, in "smooth-type" lipopolysaccharides, a third region, named O-chain, consisting of repetitive subunits of one to eight monosaccharides responsible for much of the immunospecificity of the bacterial cell.

Carbohydrate Conformation↗
PubMed2004

The extracellular polysaccharide of Porphyridium sp.: an NMR study of lithium-resistant oligosaccharidic fragments.

This study deals with the chemical characterization of an extracellular polysaccharide produced by the unicellular red alga Porphyridium sp. The sugar moiety of this polymer is composed of three neutral monosaccharides (Xyl, Glc, and Gal) and one uronic acid (GlcA). Proteins represent 5.5% of the dry weight of the polymer. Uronic degradation of this exopolysaccharide with lithium in ethylenediamine yielded two different oligosaccharides. The absolute configuration of the constitutive monosaccharides was chemically determined and revealed the presence of D-Xyl, D-Glc, D-, and L-Gal. The following oligosaccharide structures were established by NMR spectroscopy: [carbohydrate structure: see text].

Carbohydrate Sequence↗
PubMed2004

The structure of the carbohydrate backbone of the lipopolysaccharide of Pectinatus frisingensis strain VTT E-79104.

The structure of the carbohydrate backbone of the lipopolysaccharide from Pectinatus frisingensis strain VTT E-79104 was analyzed using chemical degradations, NMR spectroscopy, mass spectrometry, and chemical methods. The LPS contains two major structural variants, differing in the presence or absence of an octasaccharide fragment. The largest structure of the carbohydrate backbone of the LPS, that could be deduced from experimental results, consists of 20 monosaccharides arranged in a nonrepetitive sequence: [carbohydrate structure: see text] where R is H or 4-O-Me-alpha-L-Fuc-(1-2)-4-O-Me-beta-Hep-(1-3)-alpha-GlcNAc-(1-2)-beta-Man-(1-3)-beta-ManNAc-(1-4)-alpha-Gal-(1-4)-beta-Hep-(1-3)-beta-GalNAc-(1- where Hep is a residue of D-glycero-D-galacto-heptose; all monosaccharides have the D-configuration except for 4-O-Me-L-Fuc and L-Ara4N. This structure is architecturally similar to the oligosaccharide system reported previously in P. frisingensis VTT E-82164 LPS, but differs from the latter in composition and also in the size of the outer region.

Acetylation↗
PubMed2005

Copper and cadmium complexation by high molecular weight materials of dominant microalgae and of water from a eutrophic reservoir.

High molecular weight materials (HMWM, >12000-14000 Da) excreted by the two cyanophyte species (Microcystis aeruginosa and Anabaena spiroides) and a diatom (Aulacoseira granulata) which are dominant phytoplankton species in a eutrophic reservoir, Barra Bonita, Brazil were investigated as copper (Cu) and cadmium (Cd) complexation agents and their monosaccharide and elemental analysis of C, H, N and S determined. Also, HMWM obtained from the reservoir water as well as from a mixture of the three algae materials were studied. The HMWM of the cyanophytes and the mixture of the three algae materials complexed Cu and Cd, whereas the HMWM of the diatom and that from the reservoir water complexed only Cu. Two classes of ligands of intermediate to weak binding strength were obtained after Scatchard plot analysis of the titration data. The cyanophytes and the mixture HMWM presented higher conditional stability constants for Cu class-1 ligands (logK1' = 9.2-9.5) than the HMWM derived from the diatom and the reservoir water (logK1' = 8.6-8.8). Higher proportions of acidic monosaccharides corresponded to higher K1' of Cu and Cd complexation, yet no relation was observed among complexation parameters and elemental analysis. This study points out Cu ligands of intermediate to weak binding strength in the excreted HMWM of dominant microalgae and in the HMWM of the reservoir water, while Cd was solely complexed by ligands isolated from the cyanophyte HMWM.

Brazil↗
PubMed2004

Chemical characterization of different sugar-casein Maillard reaction products and protective effects on chemical-induced cytotoxicity of Caco-2 cells.

This study examined the chemical modification of casein with three monosaccharides [e.g., glucose (Glc), fructose (fru), and ribose (Rib)], following prolonged gentle heating to product the Maillard reaction (MR). Changes in chemical modification of casein in different sugar-casein MR was monitored using temporal patters of change in fluorescence development, UV absorbance and casein molecular mass, which was studied using SDS-PAGE and MALDI-TOF mass spectrometry. Rib-casein MRP exhibited significantly (p<0.05) advanced fluorescence development at three days, compared to Glc- and Fru-casein MRPs, which corresponded to marked (p<0.05) differences in greater UV absorption of Rib-casein MRPs later on after 15 days of processing. These results were associated with the generation of different high molecular weight complexes generated from the Rib-casein MR, compared to Glu- and Fru-casein MRPs, respectively. Antioxidant activity of all three sugar-modified caseins was also assessed when cultured with Caco-2 cells. A significant, but similar protective effect against 2,2'-azobis-(2-amidinopropane)dihydrochloride (AAPH) radical-induced cytotoxicity, and ferrous- and cupric-induced toxicity of Caco-2 cells was observed for all three sugar-casein MRPs. However, these protective effects were not significantly different among the sugar-modified caseins and native casein. The results suggest that protection of Caco-2 cells from free radical-ferrous- and cupric-induced cytotoxicity by casein was not altered by modification by MR, regardless of source of monosaccharide involved in the reaction.

Amidines↗
PubMed2005

Antiangiogenic activities of polysaccharides isolated from medicinal fungi.

Extracted polysaccharides from medicinal fungi, including Antrodia cinnamomea, Antrodia malicola, Antrodia xantha, Antrodiella liebmannii, Agaricus murrill, and Rigidoporus ulmarius, were investigated for their effects on vascular endothelial growth factor (VEGF)-induced tube formation in endothelial cells (ECs). Chemical analysis revealed that myo-inositol, sorbitol, fucose, galactosamine, glucosamine, galactose, glucose, and mannose were the neutral sugars in these polysaccharides. These fungal polysaccharides showed no toxicity to ECs. For the inhibition of endothelial tube formation, extracted polysaccharides from A. xantha and R. ulmarius were shown to produce greater inhibition compared to those from other fungi. Fucose, glucose and mannose were the predominant monosaccharides from these two fungi. These results suggest that monosaccharides may play a role in the inhibitory effect of these fungi on endothelial tube formation. In contrast to the inhibition on tube formation from polysaccharides of A. cinnamomea and A. malicola, polysaccharides from A. xantha and R. ulmarius, with molecular weight between 2693-2876 and 304-325 kDa, were critical for this inhibitory activity. Our results show that polysaccharides isolated from A. xantha and R. ulmarius provide greater antiangiogenesis than those from commercialized A. murrill (Brazilian mushroom) and A. cinnamomea. These studies provide a basis for the potential development of these polysaccharides for antiangiogenesis usage.

Angiogenesis Inhibitors↗
PubMed2004

Purification and characterization of the L-fucose transporter.

L-Fucose is a monosaccharide present in low levels in the serum. It is, however, a common structural component of glycoproteins. L-Fucose is accumulated in eukaryotic cells by a specific, facilitative diffusion transport system which has been designated the fucose transporter. In this study, purification of the transporter from mouse brain was performed by detergent extraction followed by ion-exchange and reactive dye ligand column chromatography. Purification was followed using a transport assay into reconstituted liposomes. A 111-fold purification with 5% yield was achieved from the crude homogenate. The apparent molecular weight of the protein was 57 kDa. Transport was found to be saturable. The K(m) and V(max) values are estimated at 3 microM and 275 pmol/min/mg, respectively. The tissue distribution of fucose transport was examined in liver, kidney, heart, lung, spleen, brain, muscle, adipose, ovary, pancreas, and thymus. Some fucose transport was found in all tissues examined. Very low levels were observed in the liver relative to all other tissues examined. The only monosaccharide which could inhibit the uptake of L-[5,6-(3)H]fucose was fucose itself.

Animals↗
PubMed2000

Studies on the structure of a lithium-treated soybean pectin: characteristics of the fragments and determination of the carbohydrate substituents of galacturonic acid.

Two galacturonic-acid-containing polysaccharide fractions (ChSS and P) were isolated from soybean meal and subjected to lithium treatment. The fragments obtained were analyzed by using monosaccharide and methylation analyses, and NMR spectroscopy. Lithium degradation of ChSS, followed by sodium borodeuteride reduction, hydrolysis, sodium borohydride reduction, and acetylation afforded alditol acetates, of which the labeled ones reflected residues linked to GalA. As followed from quantifications of the labeled and non-labeled alditols from each constituent monosaccharide by GLC-EIMS, 6 mol% of Ara, 22 mol% of Fuc, 13 mol% of Gal, 53 mol% of Rha, and 57 mol% of Xyl are glycosidically linked to GalA. Analysis of the lithium-treated polymer revealed that it contains arabinogalactan side chains linked to Rha O-4, which consist of a beta-(1 --> 4)-linked galactan substituted with highly branched arabinan chains. On average, an arabinogalactan chain contains up to 29 Gal and 25 Ara residues. Surface plasmon resonance was used to determine conditions for affinity chromatography. Furthermore, this technique confirmed the presence of terminal alpha-Fuc residues in ChSS. Polysaccharide P turned out to be relatively resistant to lithium degradation.

Chromatography, High Pressure Liquid↗
PubMed1998

Measurement of long-range carbon-carbon coupling constants in a uniformly enriched complex polysaccharide.

A quantitative coherence transfer scheme for 1H-detected measurement of long-range carbon-carbon coupling constants in NMR spectra of complex carbohydrates is described. It is applied to a uniformly highly 13C-enriched monosaccharide and to a complex cell wall polysaccharide from Streptococcus mitis J22 having seven distinct sugars in the repeating subunit. Coupling values within the ring were compared to published values for monosaccharides to demonstrate the validity of the method. An attempt was made to relate coupling constants between carbon atoms across the glycosidic linkage to the dihedral angles of a recently published flexible model for the polysaccharide which is based on 3JCH data. The experimental coupling constants do not agree with any single conformation demonstrating that the repeating subunit of the polysaccharide must be flexible. This conclusion is in accord with results of molecular modeling nuclear Overhauser effect and 3JCH data.

Carbohydrate Sequence↗
PubMed1998

Conformational differences among mono- and oligosaccharide fragments of O-specific polysaccharides of Vibrio cholerae O1 revealed by circular dichroism.

The circular dichroism (CD) of synthetic mono- and oligosaccharides that represent the terminal, non-reducing group of O-antigens of Vibrio cholerae O1 from the subtypes Ogawa and Inaba was measured in various solvents. We found differences in the CD of the monosaccharides of these subtypes that decrease with increasing chain lengths of the oligosaccharides. The differences can be explained by different orientations of the N-acyl side chain of the terminal monosaccharides. The linear relationship of ellipticity versus the number of residues in an oligosaccharide chain follows the principle of optical superposition. This, together with a similar contribution by internal units to the overall ellipticity, suggests an identical, regular conformation of oligosaccharide fragments of both Ogawa and Inaba series.

Carbohydrate Conformation↗
PubMed1998

Proposition for the biochemical mechanism occurring in the sucrose isomerase active site.

Sucrose conversion by sucrose isomerase from Protaminobacter rubrum, Serratia plymuthica and Erwinia rhapontici was investigated in the presence of different monosaccharides in the reaction mixture. These conditions led to inhibitory effects and to glucosyl transfer of the glucose moiety of sucrose to the exogen monosaccharide. Comparison of the structure of the different inhibitors and acceptors has allowed us to suppose the binding of the sucrose molecule into the active site, and thereafter, to propose the possible biochemical reactions leading to the formation of different products from sucrose. This study also underlines the close homologies between these enzymes.

Binding Sites↗
PubMed2000

Enhancing effect of saccharides on the mutagenicity of 2-chloro-4-methylthiobutanoic acid.

The mutagenicity of 2-chloro-4-methylthiobutanoic acid (CMBA), a nitrite-treated Sanma fish mutagen, in Salmonella typhimurium TA100 was enhanced by addition of D-glucose during the CMBA-treatment. Several other monosaccharides also enhanced the mutagenicity of CMBA, and the order of the enhancing potency was found to be D-mannose, D-glucose>D-fructose, D-ribose, D-galactose. A disaccharide, maltose, showed only little enhancement. No enhancement was found with L-glucose. We investigated whether saccharides affect uptake of [methyl-14C]CMBA into S. typhimurium TA100. Saccharides which enhanced CMBA-induced mutagenesis increased the uptake. L-Glucose did not enhance the uptake. There was good correlation between the enhanced mutagenesis and increased radioactivity in Salmonella, suggesting that the enhancing effect of monosaccharide on the CMBA-induced mutagenesis results from the enhanced uptake of the mutagen into bacteria.

Butyrates↗
PubMed1985

Carbohydrate composition of the second, third and fifth components and factors B and D of human complement.

The carbohydrate composition of the second, third and fifth components of human complement (C2, C3 and C5) and of factors B and D was determined employing gas-chromatographic and mass-spectrometric methods. C2 was found to contain 15.9% carbohydrate composed of fucose, galactose, mannose, N-acetylglucosamine and N-acetylneuraminate (approximate molar ratio 1:4:9:9:4). N-acetylglucosamine and mannose (approximate molar ratio 1:4), amounting to 1.7% of the mass of the molecule, were the only monosaccharides detected in C3. C5 contained 3.8% carbohydrate composed of galactose, mannose, N-acetylglucosamine and N-acetylneuraminate (approximate molar ratio 2:4:4-5:2). The carbohydrate moiety of B consisted of fucose, galactose, mannose, N-acetylglucosamine and N-acetylneuraminate (molar ratio 1:2:3:4:2). The total carbohydrate content of B was estimated at 8.6%. In addition to these monosaccharides, glucose (0.4-0.9%) was also detected in all preparations analysed. Glucose was the only sugar detected in D.

Carbohydrates↗
PubMed2003

The role of glycolysis and gluconeogenesis in the cytoprotection of neuroblastoma cells against 1-methyl 4-phenylpyridinium ion toxicity.

1-Methyl-4-phenylpyridinium (MPP+) is a mitochondrial Complex I inhibitor and is frequently used to investigate the pathological degeneration of neurons associated with Parkinson's disease (PD). In vitro, extracellular concentration of glucose is one of the most critical factors in establishing the vulnerability of neurons to MPP+ toxicity. While glucose is the primary energy fuel for the brain, central nervous system (CNS) neurons can also take up and utilize other metabolic intermediates for energy. In this study, we compared various monosaccharides, disaccharides, nutritive/non-nutritive sugar alcohols, glycolytic and gluconeogenic metabolic intermediates for their cytoprotection against MPP+ in murine brain neuroblastoma cells. Several monosaccharides were effective against MMP+ (500 microM) including glucose, fructose and mannose, which restored cell viability to 109 +/- 5%, 70 +/- 5%, 99 +/- 3% of live controls, respectively. Slight protective effects were observed in the presence of 3-phosphoglyceric acid and glucose-6-phosphate; however, no protective effects were exhibited by galactose, sucrose, sorbitol, mannitol, glycerol or various gluconeogenic and ketogenic amino acids. On the other hand, fructose 1,6 bisphosphate and gluconeogenic energy intermediates [pyruvic acid, malic acid and phospho(enol)pyruvate (PEP)] were neuroprotective against MPP+. The gluconeogenic intermediates elevated intracellular levels of ATP and reduced propidium iodide (PI) nucleic acid staining to live controls, but did not alter the MPP(+)-induced loss of mitochondrial O2 consumption. These data indicate that malic acid, pyruvic acid and PEP contribute to anaerobic substrate level phosphorylation. The use of hydrazine sulfate to impede gluconeogenesis through PEP carboxykinase (PEPCK) inhibition heightened the protective effects of energy substrates possibly due to attenuated ATP demands from pyruvate carboxylase (PC) activity and pyruvate mitochondrial transport. It was concluded from these studies that several metabolic intermediates are effective in fueling anaerobic glycolysis during mitochondrial inhibition by MPP+.

1-Methyl-4-phenylpyridinium↗
PubMed1996

Modeling polysaccharides: present status and challenges.

The most recent tools that have been developed for modeling the three-dimensional features of polysaccharides and carbohydrate polymers are presented. The presentation starts with a description of the conformations of the monosaccharides, and of the flexible rings such as in the case of five-membered rings, and a thorough description of the conformational space that is available for a disaccharide unit, either in vacuo or in an aqueous phase. The extension to the modeling of the parent polysaccharides is addressed, based on the assumption that owing to the size and relative rigidity of the intervening monosaccharides units, the rotations at a particular linkage can be, under some conditions, considered as independent of nearest neighbor interactions. Appropriate modeling techniques are described that can provide insights into the dimensions of the chain in a solution which is best described as a random coil accompanied by the occurrence of local "helical" regions. With the help of such descriptors such as helical parameters, the ordered state of polysaccharide strands can be readily characterized. The generation of double or triple helices can be then attempted in order to explore the occurrence of such multi-stranded arrangements that may be energetically stable. The final step in the determination of the structure of polysaccharides in the ordered state, is the investigation of the interactions of different helices. This may lead to either the best arrangement(s) between two polymeric chains, or to the prediction of the dimensions, and the symmetry of a three-dimensional lattice. Some of the tools which have been developed should allow automatic scarches for meaningful correlations between structures and functions, through exploratory data analysis. Structure-function or structure-property correlation could be then used to model changes arising from structural alterations. This would open the field of polysaccharide engineering.

Carbohydrate Conformation↗