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PubMed1994

Macrophage recognition of saccharide chains on the erythrocytes damaged by iron-catalyzed oxidation.

Mouse erythrocytes oxidized with an iron catalyst ADP/Fe3+ chelate attached to the monolayers of mouse resident and thioglycollate-induced peritoneal macrophages in the absence of serum, indicating that the macrophages recognized the oxidized erythrocytes. The recognition was partially prevented when the oxidized cells were treated with dithiothreitol, suggesting that disulfide formation is involved, in part, in the generation of the membrane sites recognized by macrophages. Phosphatidylserine is unlikely to be the determinant on the oxidized cells because it was not detected on the outer surface of the oxidized cells. The recognition by resident macrophages was effectively inhibited by N-acetylneuramin lactose, N-acetylneuraminic acid, glycophorin A, and disialoganglioside GD1a, but poorly by lactose, asialoglycophorin A, and monosialoganglioside GM1. In addition, the recognition was partially inhibited by L-fucose and human lactoferrin. The recognition by thioglycollate-induced macrophages was not inhibited by glycophorin A but was partially inhibited by L-fucose, lactoferrin, and oligosaccharides from band 3 glycoprotein. Enzymatic cleavage of the poly-N-acetyllactosaminyl saccharide chains of band 3 and lactoferrin resulted in a loss of the inhibitory activity. These results suggest that sialosaccharide chains of ADP/Fe(3+)-oxidized erythrocytes, possibly those on glycophorin A, are mainly involved in the recognition by resident macrophages, and poly-N-acetyllactosaminyl saccharide chains, possibly those on band 3, are partly involved in the recognition both by resident and thioglycollate-induced macrophages. Oxidation of erythrocytes may induce change in these membrane glycoproteins, like aggregation, which renders their saccharide chains susceptible to the macrophage recognition.

Adenosine Diphosphate↗

PubMed1997

Dramatic saccharide-mediated protection of chaotropic-induced deactivation of concanavalin A.

This work provides evidence of a physical instance in which some proteins that are usually inactivated under strong chaotropic conditions may become fully resistant through the occupancy of their binding sites with suitable ligands. In this regard, we found that Moluccella laevis lectin remains stable in the presence of denaturant concentrations of urea when an appropriate saccharide is bound to the protein (Alperin, D.M., Latter, H., Lis, H., and Sharon, N. (1992) Biochem. J. 285, 1-4). Extending this finding, we now demonstrate that the occupancy of the ligand binding sites of concanavalin A (Con A) with appropriate carbohydrates completely prevents the denaturation course elicited by 8 M urea at pH 7.4. In addition, the protecting efficiency of the saccharides was shown to be directly related to their specificities for the lectin. The observed saccharide protection follows the order:methyl alpha-D-mannopyranoside > methyl alpha-D-glucopyr-anoside > mannose > fructose > glucose. Concomitantly, the active tetrameric lectin with a molecular mass of approximately 105 kDa is preserved in 8 M urea when methyl alpha-D-mannopyranoside (100 mM) is present in the medium.

Allosteric Regulation↗

PubMed2001

Quantitative determination of saccharide surfactants in protein samples by liquid chromatography coupled to electrospray ionization mass spectrometry.

A direct and highly selective method, combining liquid chromatography (LC) with electrospray ionization mass spectrometry (ESI-MS), has been developed for quantifying saccharide surfactants. Saccharide surfactants, such as n-octyl-beta-d-glucopyranoside (NOG), are widely used to solubilize or refold membrane-bound or lipophilic proteins. In the present study, we have developed an LC-MS method to quantify NOG in protein samples. Protein-bound NOG was completely dissociated from proteins by reversed-phase LC, allowing the total amount of saccharide surfactant in protein samples to be quantified by MS. A chemical analog of NOG was used as an internal standard for improving the reproducibility of the method. Linearity was found in the range of 10 microg/mL-1.0 mg/mL NOG concentrations. Seven major surfactant oligomeric ions were detected under the ionization conditions applied and their relative abundance was essentially unchanged over the range of 0.05-1.0 mg/mL NOG concentrations. Consequently, ions with characteristic mass-to-charge ratios could be used for quantification of NOG. Analytical accuracy of the method was examined by determining the amounts of NOG recovered from apolipoprotein A-I and myoglobin samples spiked with NOG.

Animals↗

PubMed1994

Structural changes of active site cleft and different saccharide binding modes in human lysozyme co-crystallized with hexa-N-acetyl-chitohexaose at pH 4.0.

Human lysozyme was co-crystallized with hexa-N-acetyl-chitohexaose, (GlcNAc)6, at pH 4.0 and 4.0 degrees C in a new orthorhombic form, where two protein molecules, MOL1 and MOL2, were contained in an asymmetric unit. The three-dimensional structure was refined to an R-factor of 17.0% at 1.6 A resolution. It was found that (GlcNAc)6 had already been cleaved to (GlcNAc)4 and (GlcNAc)2. In MOL1, (GlcNAc)4 was bound to the A, B, C, and D subsites, and binding sites of (GlcNAc)2 were close to the E and F subsites proposed on the basis of model building by Phillips and his colleagues. In MOL2, only the (GlcNAc)4 moiety could be found in the A, B, C and D subsites. Significant shifts of the backbone atoms were observed in the region of residues 102 to 120, which composed one side of the wall of the active site cleft. Consequently, the active cleft, with respect to the saccharide binding sites A, B and C, is narrower in both protein molecules. The residues 109 to 111 in site D of MOL1 are moved toward saccharide residue D, whereas those of MOL2 are only slightly shifted. In spite of these facts, the saccharide residues in site MOL1 and MOL2 are moved inside of the cleft. The distribution of water molecules and the hydrogen bond network in site D differ between the structures of MOL1 and MOL2. These structural changes in the active site cleft may be responsible for accommodating the substrate and releasing the products of hydrolysis. These results suggest that the three-dimensional structures of MOL1 and MOL2 remain in intermediate states between a transition state and an enzyme/product complex state.

Binding Sites↗

PubMed2001

Influences of incubation temperature and various saccharides on the production of organic acids and gases by gut microbes of rainbow trout Oncorhynchus mykiss in a micro-scale batch culture.

We studied the influence of incubation temperature and additional saccharides on the metabolism of hindgut microbes of the rainbow trout Oncorhynchus mykiss in a 50 microl-scale batch culture system. Intestinal contents of rainbow trout reared at 15 degrees C were incubated with glucose, lactosucrose, sodium alginate or colloidal chitin (each 10 g/l) at 15 degrees C or 25 degrees C for 12 h. Levels of organic acids at 0 h and 12 h of incubation were quantified with HPLC. We also monitored gas release from these cultures during incubation. The main product was iso-butyric acid, except for the cultures with colloidal chitin where no net production of organic acids was observed. We detected higher levels of iso-butyric acid in cultures with lactosucrose than in the other cultures. Net production of this acid was less in cultures with colloidal chitin than in blank cultures. The volume of released gas was larger when incubated at 25 degrees C than at 15 degrees C. Cultures with colloidal chitin released more gas than blank cultures when they were incubated at 15 degrees C. Cultures with sodium alginate released less gas than blank cultures irrespective of incubation temperature. These results indicate that the hindgut microbes of this carnivorous fish mainly produce branched-chain fatty acids, very likely by microbial digestion of nitrogenous materials rather than saccharides. However, additional saccharides affected production of branched-chain fatty acids. The influence of incubation temperature in the present study also suggested that the environmental temperature of host fish should affect microbial digestion in the fish gut.

Acids↗

PubMed1991

Polyacrylamide gel electrophoresis of reducing saccharides labeled with the fluorophore 2-aminoacridone: subpicomolar detection using an imaging system based on a cooled charge-coupled device.

Numerous monosaccharides and oligosaccharides were derivatized at their reducing end groups with the fluorophore 2-aminoacridone. The resulting fluorescent compounds were separated by PAGE using two different buffer systems. One of these, a Tris borate buffer, enabled all of the fluorescent saccharide derivatives tested to be electrophoresed and various positional isomers, anomers, and epimers could be separated. The other system consisted of a discontinuous Tris-HCl/Tris-glycine buffer and enabled the electrophoresis of acidic, but not neutral, saccharide derivatives. The acidic and neutral saccharides could thus be distinguished unequivocally. The fluorescent labeling procedure was virtually quantitative and as little as 0.63 pmol could be detected photographically when gels were illuminated by uv light. When gels were viewed using an imaging system based on a cooled charge-coupled device, as little as 0.2 pmol was detected. The method may be useful for the structural analysis of the carbohydrates of glycoconjugates and other naturally occurring oligosaccharides.

Aminoacridines↗

PubMed1993

Structural studies of the saccharide part of the cell envelope lipopolysaccharide from Haemophilus influenzae strain AH1-3 (lic3+).

The structure of the saccharide part of the lipopolysaccharide from Haemophilus influenzae strain AH1-3 (lic3+) has been investigated. The saccharide was obtained from the lipopolysaccharide by mild acid hydrolysis followed by high-performance anion-exchange chromatography, and isolated fractions were studied by methylation analysis, NMR spectroscopy, and FAB mass spectrometry. The major saccharide is a heptasaccharide with the following structure, [formula: see text] in which Kdo is 3-deoxy-D-manno-oct-2-ulosonic acid and PEA is 2-aminoethyl phosphate. Hep is identified as L-glycero-D-manno-heptose. The absolute configuration of the phosphorylated heptose is tentative only.

Carbohydrate Sequence↗

PubMed1983

Inhibition of human NK-induced cell lysis and soluble cell-lytic molecules with anti-human LT antisera and various saccharides.

The present study examines and compares the cytolysis of K-562 and MOLT-4 cells mediated by human natural killer (NK) cells from fresh peripheral blood and lymphotoxins (LT) derived from human lymphoid cell populations after lectin stimulation in vitro. Lymphotoxins were obtained from 5-hr concanavalin A (Con A)-restimulated human peripheral blood lymphocytes (PBL) which were precultured for 5 days in medium and fetal calf serum or with allogeneic human B-lymphoid cell lines. Two classes of probes were employed in both direct (cell) and indirect (supernatant) induced target-cell lysis: (a) various saccharides and (b) antibodies reactive with human LT forms. Two sugars, N-acetylglucosamine and alpha-methylmannoside, were able to inhibit direct cell lysis of both MOLT-4 and K-562 target cells. However, saccharide inhibition was distinct for each type of target even when effector cells were obtained from the same donor. These same saccharides were also able to inhibit 20-30% of the total LT activity in a supernatant for L-929 cells and 50-90% of the lytic activity on MOLT-4 cells. Anti-human F(ab')2 (IgG) and rabbit anti-alpha 2 LT sera blocked direct cell lysis of MOLT-4 and K-562 targets in 50% of the experiments. The anti-alpha 2 LT serum only recognizes a portion of the LT forms in these supernatants. These results reveal that, while both direct and indirect cell lysis are complex phenomena, they may both occur in some cases by a common mechanism(s).

Animals↗

PubMed2006

The synthesis of amphipathic prodrugs of 1,2-diol drugs with saccharide conjugates by high regioselective enzymatic protocol.

A facile, high regioselective enzymatic synthesis approach for the preparation of amphipathic prodrugs with saccharides of mephenesin and chlorphenesin was developed. Firstly, transesterification of two drugs with divinyl dicarboxylates with different carbon chain length was performed under the catalysis of Candida antarctica lipase acrylic resin and Lipozyme in anhydrous acetone at 50 degrees C, respectively. A series of lipophilic derivatives with vinyl groups of mephenesin and chlorphenesin were prepared. The influences of different organic solvents, enzyme sources, reaction time, and the acylation reagents on the synthesis of vinyl esters were investigated. And then, protease-catalyzed high regioselective acylation of D-glucose and D-mannose with vinyl esters of mephenesin and chlorphenesin gave drug-saccharide derivatives in good yields. The studies of lipophilicity and hydrolysis in vitro of prodrugs verified that drug-saccharide derivatives had amphipathic properties, and both lipophilic and amphipathic drug derivatives had obvious controlled release characteristics.

Acylation↗

PubMed2006

Formation of the intermediate nitronyl nitroxide-anthracene dyad sensing saccharides.

We design a new saccharides sensor based on the ensemble of compound 2 with a boronic group and compound 3 with two phenolic -OH groups, taking advantage of the fluorescence quenching ability of nitronyl nitroxides and reversible boronate formation between boronic acid and diol. The results show that the fluorescence of compound 2 was largely quenched upon addition of compound 3 due to the formation of the intermediate nitronyl nitroxide-anthracene dyad 1. Sequential addition of saccharides such as fructose to the ensemble of compounds 2 and 3 together with dyad 1 induced the fluorescence enhancement. These results clearly demonstrate the possibility to employ the ensemble of compounds 2 and 3 (with dyad 1) to sense saccharides.

Anthracenes↗

PubMed2006

Construction of saccharide-modified DNAs by DNA polymerase.

Novel deoxyribonucleotide triphosphates bearing maltose or lactose groups were synthesized as substrates for DNA polymerase. The incorporation efficiencies of these modified substrates were investigated in both primer extension reactions and PCR. The stability and conformation of saccharide-modified dsDNAs were assessed by UV absorbance melting experiments and CD analysis. Enzymatic incorporation of saccharide-modified substrates can be used for the efficient production of saccharide-modified DNAs.

Carbohydrate Sequence↗

PubMed2006

Enhanced sucrose and Polycose preference in sweet "sensitive" (C57BL/6J) and "subsensitive" (129P3/J) mice after experience with these saccharides.

Prior research with inbred mouse strains indicates that C57BL/6J (B6) mice display stronger preference and acceptance for various sweeteners than do 129P3/J (129) mice. Experiment 1 examined the extent to which this strain difference could be modified by repeated exposure to sucrose. Sucrose-naive 129 mice displayed weaker preferences than did B6 mice for 0.5% to 4% sucrose solutions during 23h/day sugar vs. water tests. Sucrose preference did not differ at 8-32% concentrations. Yet, when retested with sucrose, the 129 and B6 mice showed identical robust preferences (>90%) for 0.5-32% solutions. The strains also did not differ in sucrose preference in tests with descending sucrose concentrations (0.5-0.0625%). Sucrose-experienced 129 mice also showed enhanced preference for dilute saccharin solutions suggesting that their sweet taste responsivity was enhanced. Experiment 2 revealed that preference for dilute saccharin solutions was enhanced by prior saccharin experience in B6 but not 129 mice. Experiment 3 tested the strains with Polycose which has a palatable taste different from that of sucrose. Polycose-naive 129 mice displayed weaker preferences for dilute (0.5-4%) but not concentrated (8-32%) Polycose solutions relative to B6 mice. In the second test series Polycose preferences were nearly identical in the two strains. In Experiments 1 and 3, prior sucrose or Polycose experience also reduced or eliminated strain differences in saccharide acceptance (absolute intake) at higher but not lower concentrations. Thus, exposure to the oral and post-oral actions of sucrose and Polycose increased saccharide preference in B6 mice and even more in 129 mice so that the strain difference virtually disappeared. Whether the 129 mice responded to the taste or other properties (e.g., odor) of the dilute saccharide solutions is not certain but their gustatory sensitivity needs to be reconsidered.

Animals↗

PubMed1979

Protection of sodium dodecyl sulfate-induced aggregation of concanalvalin A by saccharide ligands.

Concanavalin A is visibly aggregated by low concentrations of sodium dodecyl sulfate, maximum aggregation being obtained at pH 4.6. Other denaturants, such as urea, guanidine hydrochloride, Triton X-100, cetyltrimethylammonium bromide, Tween 80, and Brij 35 are ineffective in promoting visible aggregation. The sodium dodecyl sulfate-induced aggregation of concanavalin A requires the presence of an intact, saccharide-ligand binding-site. Rapid and complete reversal of the detergent effect was achieved by use of saccharides which bind to the lectin. Such compounds as tryptophan and o-nitrophenyl beta-D-galactopyranoside did not inhibit the aggregation of concanavalin A by sodium dodecyl sulfate, suggesting that the detergent does not bind the hydrophobic pocket on the surface of the protein. The results suggest that concanavalin A may have an additional, ligand-binding site which is metal-dependent and which can be modified by the addition of a saccharide ligand.

Chemical Phenomena↗

PubMed1991

Further characterization of the saccharide specificity of peanut (Arachis hypogaea) agglutinin.

2-Dansylamino-2-deoxy-D-galactose (GalNDns) has been shown to bind to peanut (Arachis hypogaea) agglutinin (PNA) in a saccharide-specific manner. This binding was accompanied by a five-fold increase in the fluorescence of GalNDns. The interaction was characterized by an association constant of 0.15 mM at 15 degrees and delta H and delta S values of -57.04 kJ.mol-1 and -118.1J.mol-1.K-1, respectively. Binding of a variety of other mono-, di- and oligo-saccharides to PNA, studied by monitoring their ability to dissociate the PNA GalNDns complex, revealed that PNA interacts with several T-antigen-related structures, such as beta-D-Galp-(1----3)-D-GalNAc, beta-D-Galp-(1----3)-alpha-D-GalpNAcOMe, and beta-D-Galp-(1----3)-alpha-D-GalpNAc-(1----3)-Ser, as well as the asialo-GM1 tetrasaccharide, with comparable affinity, thus showing that this lectin does not discriminate between saccharides in which the penultimate sugar of the beta-D-Galp-(1----3)-D-GalNAc unit is the alpha or beta anomer, in contrast to jacalin (Artocarpus integrifolia agglutinin), another anti T-lectin which preferentially binds to beta-D-Galp-(1----3)-alpha-D-GalNAc and does not recognize beta-D-Galp-(1----3)-beta-D-GalNAc or the related asialo-GM1 oligosaccharide. These studies also indicated that, in the extended combining region of PNA which accommodates a disaccharide, the primary subsite (subsite A) is highly specific for D-galactose, whereas the secondary subsite (subsite B) is less specific and can accommodate various structures, such as D-galactose, 2-acetamido-2-deoxy-D-galactose, D-glucose, and 2-acetamido-2-deoxy-D-glucose.

Arachis↗

PubMed1987

Carbohydrate-induced hyperphagia and obesity in the rat: effects of saccharide type, form, and taste.

Adult female rats were fed, in addition to chow and water, a carbohydrate source that differed in type (glucose, sucrose, or polysaccharide), form (32% solution, powder, or gel), or taste (very sweet, minimally sweet, or bitter). A control group was fed only chow and water during the 40-day experiment. The groups fed the glucose solution, sucrose solution, or one of three polysaccharide solutions (Polycose, maltose-dextrin 10, maltose-dextrin 42) all overrate and gained more body weight and fat than did the control group. The carbohydrate solution groups did not differ in their total caloric intake, weight gain, percent body fat, or basal insulin level. The polysaccharide groups, however, consumed more carbohydrate than did the sugar groups. The groups fed glucose, sucrose, or Polycose in powder form consumed less carbohydrate and total calories, gained less weight and fat, and had lower insulin levels than did the groups fed the saccharides in solution form. The powder groups did not reliably differ from the control group on these measures. Rats fed Polycose in solution form or in a solid gel form (32% Polycose + 1% agar) were similar in their carbohydrate intake, total caloric intake, weight gain, and percent body fat. Rats fed Polycose solutions that were minimally sweet (32% Polycose), sweet (0.2% saccharin + 32% Polycose), or bitter [0.05% sucrose octa acetate (SOA) + 32% Polycose] did not differ in their Polycose intake, total caloric intake, weight gain, or percent body fat. The results demonstrate that saccharide form is more important than saccharide type or taste in promoting hyperphagia and obesity in rats. The Polycose gel findings further indicate that it is the water of hydration, not liquidity that is responsible for the hyperphagia-inducing effect of carbohydrate solutions.

Animals↗

PubMed2002

Preparation and dissolution characteristics of griseofulvin solid dispersions with saccharides.

To improve the solubility of poorly water-soluble drugs, we studied physical characteristics of griseofulvin (GF) solid dispersions with saccharides as the dispersion carrier using a roll mixing method. In all carriers tested, roll mixtures of GF and saccharides gradually became amorphous, and the solubility of GF increased. The solubility of GF was higher in the mixtures with higher molecular weight carriers such as corn starch and processed starch. The dissolution of GF was markedly improved by the GF-Britishgum roll mixture. The initial dissolution rate of these mixtures was 170-fold higher than GF alone. The surface tension of carrier aqueous solutions was low in the processed starch with branched sugar chains. The initial dissolution rate of GF in physical mixtures was correlated with the surface tension of carrier aqueous solutions. The stability of the amorphous state of GF at a high humidity was maintained in the mixtures with carriers with a high molecular weight. These results indicated that the solubility of GF was markedly improved in the roll mixtures. It was suggested that the saccharides with a high molecular weight are useful carriers for solid dispersions.

Chemistry, Pharmaceutical↗

PubMed2002

Clusters, bundles, arrays and lattices: novel mechanisms for lectin-saccharide-mediated cellular interactions.

Multivalent protein-carbohydrate interactions regulate essential cellular events, including cell proliferation, adhesion and death. These multivalent interactions can create homogeneous complexes of lectins, such as the galectins, with their saccharide ligands. Lectin-saccharide complexes can concentrate specific glycoproteins or glycolipids within the lattice, while excluding other cell surface molecules. The formation of lectin-saccharide lattices on the cell surface can thus organize the plasma membrane into specialized domains that perform unique functions.

Animals↗

PubMed2003

Labelling saccharides with phenylhydrazine for electrospray and matrix-assisted laser desorption-ionization mass spectrometry.

A well-known reaction of carbonyl compounds with phenylhydrazine has been applied to saccharides, providing increased sensitivity for mass spectrometric (MS) and ultraviolet (UV) detection during high-performance liquid chromatographic (HPLC) separations. After a simple derivatization procedure for 1 h at 70 degrees C and purification of the reaction mixture from excess reagent by extraction, the sugar derivatives were characterized by direct injection or on-line HPLC/electrospray ionization (ESI) and by matrix-assisted laser desorption/ionization (MALDI) MS. Because no salts are used or produced upon reaction, this procedure is very simple and suitable for the tagging of saccharides. The reaction allows for on-target derivatization and products are very stable. The derivatization procedure has been applied to commercially-obtained small saccharides and standard N-linked oligosaccharides. Lastly, hen ovalbumin N-glycans were detached enzymatically and characterized by MALDI-MS as their phenylhydrazone derivatives.

Carbohydrates↗