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Comparison of saccharides as osmotic impermeants during hypothermic lung graft preservation.

We have previously shown that the trisaccharide raffinose is largely responsible for the superior lung graft performance seen after storage in University of Wisconsin solution. To investigate the use of osmotic agents in perfusates for hypothermic lung graft storage, we compared saccharides of various molecular weights in an isolated rat lung model. Grafts were flushed with 1 of 6 preservation solutions (n=5 each group) containing either a monosaccharide (glucose [G] or fructose [F]), disaccharide (trehalose [T] or sucrose [S]), or trisaccharide (raffinose [R] or melezitose [M]. Grafts were stored for 6 hours at 4 degrees C, reperfused by a veno-venous circuit from an anesthetized support animal for 60 min, and ventilated with room air. The best graft function was seen when trisaccharides were used (PO2; R 126 +/- 3 mm Hg, M 129 +/- 3 mm Hg, blood flows: R 10.2 +/- 0.42 ml/min, M 10.3 +/- 0.22 ml/min). Disaccharides produced similar oxygenation (T 133 +/- 3 mm Hg, S 129 +/- 3 mm Hg) and flows (T 10.3 +/- 0.29 ml/min, S 9.7 +/- 0.4 ml/min) at 60 min, but initial flows were reduced. Monosaccharides produced the least satisfactory graft function, with impaired oxygenation (F 110 +/- 14 mm Hg, P<0.05; G 69 +/- 10 mm Hg, P<0.01) and blood flows (G 6.5 +/- 0.6 ml/min, F 9.1 +/- 0.6 ml/min, P<0.01 each). Only glucose-stored lungs demonstrated a significant decrease in compliance (P<0.01) and weight gain (P<0.01). The worst results were seen with glucose, which is the osmotic agent most commonly used for clinical lung storage. A solution containing a trisaccharide or disaccharide may be more appropriate for this purpose.

Animals↗

Bacitracin Inhibits the Synthesis of Lipid-linked Saccharides and Glycoproteins in Plants.

The particulate enzyme fraction from mung bean (Phaseolus aureus) seedlings catalyzes the incorporation of mannose from GDP-[(14)C]mannose into mannosyl-phosphoryl-dolichol and of N-acetylglucosamine from UDP-[(3)H]N-acetylglucosamine into N-acetylglucosamine-pyrophosphoryl-polyisoprenol. Bacitracin inhibits the transfer of both of these sugars into the lipid-linked saccharides with 50% inhibition being observed at 5 mm bacitracin. This antibiotic did not inhibit the transfer of glucose from UDP-[(14)C]glucose into steryl glucosides or the incorporation of glucose into a cell wall glucan. Bacitracin also inhibited the in vivo incorporation of [(14)C]mannose into mannosyl-phosphoryl-dolichol and into glycoprotein by carrot (Daucus carota) slices. While bacitracin also inhibited the incorporation of lysine into proteins by these slices, protein synthesis was less sensitive than glycosylation. Thus at 2 mm bacitracin glycosylation was inhibited 92%, while protein synthesis was inhibited only 50%.

Journal Article↗

Structural energetics of protein-carbohydrate interactions: Insights derived from the study of lysozyme binding to its natural saccharide inhibitors.

High-sensitivity isothermal titration calorimetry was used to characterize the binding of the glycohydrolitic enzyme hen egg-white lysozyme to its natural saccharide inhibitors, chitobiose and chitrotriose. Measurements were done at a pH of 4.7, in the 15 degrees C -45 degrees C temperature range. Using a structural-energetic parameterization derived previously for lectin-carbohydrate associations, both binding enthalpies and entropies for the present systems and for the complex of chitobiose with turkey egg-white lysozyme from the literature were correctly accounted for. These observations suggest that both lysozymes and lectins follow the same structural-energetic behavior in the binding to their ligands. From the analysis of lysozyme data in conjunction with other binding data reported in the literature, an ad hoc parameterization of DeltaCp for protein-carbohydrate complexes was derived for the first time. The novel parameters for both polar and apolar surface areas differed significantly from correlations obtained previously from model compounds and protein-folding data. As DeltaCp is extremely sensitive to changes in solvent structure, this finding indicates that protein-carbohydrate complexes have distinctive hydration properties. According to our analysis, the dehydration of polar groups is the major cause for the observed decrease in DeltaCp, which implies that these groups behave hydrophobically. The contribution of apolar surface areas was found of the expected sign, but their specific weight is much smaller than those obtained in other correlations. This small contribution to DeltaCp is consistent with Lemieux's hypothesis of a low degree of hydration of apolar surfaces on carbohydrates.

Animals↗

Synthesis of a divalent sialyl Lewis x O-glycan, a potent inhibitor of lymphocyte-endothelium adhesion. Evidence that multivalency enhances the saccharide binding to L-selectin.

The recognition of cell-surface L-selectin by its carbohydrate ligands causes lymphocytes to roll on capillary endothelium at sites of inflammation. As this primary contact is a prerequisite for extravasation of the leukocytes to the tissue, its inhibition by free oligosaccharides capable of competing with the natural L-selectin ligands in an attractive therapeutic possibility. The exact structures of the biological ligands of L-selectin are not yet known, but the principal carbohydrate epitopes share some structural features: they are O-glycosidically linked mucin-type oligosaccharides with N-acetyllactosamine backbone, which is 3'-sialylated or 3'-sulfated, 3-fucosylated and sometimes 6- or 6'-sulfated at the distal N-acetyllactosamine termini. Multivalency of the ligand, which is believed to enhance the binding, is achieved by a branched polylactosamine backbone or by a clustered array of O-glycans. We report here enzymic synthesis of a large oligosaccharide fulfilling several of the features characteristic to the L-selectin ligands: it is a dodecameric O-glycosidic core-2-type oligosaccharide alditol with a branched polylactosamine backbone carrying two distal alpha-2,3'-sialylated and alpha-1,3-fucosylated N-acetyl-lactosamine groups (sialyl Lewis x, sialyl Le(x)). The structure of each saccharide on the synthesis route from disaccharide Gal beta 1-3GalNAc to the dodecasaccharide alditol was established by several methods including one- and two-dimensional 1H-NMR spectroscopy. The last step of the synthesis, the alpha-1,3-fucosylation of the 6-linked arm proceeded sluggishly, and was associated with a noticeable shift in H1 resonance of the GlcNAc residue of the branch-bearing N-acetyllactosamine unit. The final synthesis product and its analogs lacking one or both of the fucose residues were tested as inhibitors of L-selectin-mediated lymphocyte-endothelium interaction in vitro in rejecting rat kidney transplant. While the non-fucosylated O-glycosidic oligosaccharide alditol did not possess any inhibitory activity, the mono-fucosylated one (i.e. monovalent sialyl Le(x)) prevented the binding significantly and the difucosylated dodecasaccharide alditol (i.e. divalent sialyl Le(x)) was a very potent inhibitor (IC50, inhibitory concentration preventing 50% of binding = 0.15 microM). Besides the multivalency, also the Gal beta 1-3GalNAc-ol sequence of the O-glycosidic core appeared to increase the affinity of the glycan to L-selectin. This was indicated by parallel inhibition experiments, where a disialylated and difucosylated branched polylactosamine decasaccharide, similar to the divalent dodecasaccharide alditol, but lacking the reduced O-glycosidic core, was a less effective inhibitor (IC50 = 0.5 microM) than the O-glycosidic dodecasaccharide alditol.

Animals↗

The saccharide chain of lupin seed conglutin gamma is not responsible for the protection of the native protein from degradation by trypsin, but facilitates the refolding of the acid-treated protein to the resistant conformation.

Native glycosylated and enzymically deglycosylated conglutin gamma (a lupin seed oligomeric protein) both showed an unusual resistance to tryptic degradation. The result of this treatment was that a single 40-residue peptide was cleaved from the N-terminus of conglutin gamma light subunit. Acid treatment of the two protein forms led to their substantial unfolding, as indicated by CD spectra. After this treatment, both polypeptides were completely degraded by trypsin after a few minutes of incubation. Conversely, trypsin pulse experiments run under renaturing conditions demonstrated a different refolding behaviour of the two proteins: the glycosylated form became resistant to trypsin after a 7-h renaturation, while the deglycosylated form required 42 h renaturation. These results were confirmed by CD spectra and reverse-phase HPLC analyses of the glycosylated and deglycosylated conglutin gamma forms. Therefore, it was concluded that the saccharide chain of conglutin gamma increased the rate of formation of a trypsin-resistant conformation upon refolding of the acid-treated protein, without playing any direct role in the protection of the native protein from proteolysis.

Amino Acid Sequence↗

A comparison of the fine saccharide-binding specificity of Dioclea grandiflora lectin and concanavalin A.

The lectin from the seeds of Dioclea grandiflora (DGL) is a Man/Glc-specific tetrameric protein with physical and saccharide-binding properties reported to be similar to that of the jack bean lectin concanavalin A (ConA). Unlike other plant lectins, both DGL and ConA bind with high affinity to the core trimannoside moiety, 3,6-di-O-(alpha-D-mannopyranosyl)-alpha-D-mannopyranoside, which is present in all asparagine-linked carbohydrates. In the present study, hemagglutination inhibition techniques have been used to investigate binding of DGL and ConA to a series of mono- and dideoxy analogs of methyl 3,6-di-O-(alpha-D-mannopyranosyl)-alpha-D-mannopyranoside and to a series of asparagine-linked oligomannose and complex oligosaccharides and glycopeptides. The results indicate that both DGL and ConA recognize epitopes on all three residues of the trimannoside: the 3-, 4-, and 6-hydroxyl groups of the alpha(1-6)Man residue, the 3-hydroxyl group of the alpha(1-3)Man residue, and the 2- and 4-hydroxyl groups of the central Man residue of the core trimannoside. However, unlike ConA, DGL does not bind to biantennary complex carbohydrates. This was confirmed by showing that biantennary complex glycopeptides do not bind to a DGL-Sepharose affinity column. Unlike ConA, DGL does not show enhanced affinity for a large N-linked oligomannose carbohydrate (Man9 glycopeptide) relative to the trimannoside. Thus, DGL and ConA share similar epitope recognition of the core trimannoside moiety. However, they exhibit differences in their fine specificities for larger N-linked oligomannose and complex carbohydrates.

Carbohydrate Conformation↗

Characterization of surface saccharides in two Corynebacterium diphtheriae strains.

Two Corynebacterium diphtheriae strains were analyzed by assays employing a battery of highly purified fluorescent lectins. From 22 lectins tested only seven with affinity to receptor molecules containing N-acetylglucosamine (D-GlcNAc), N-acetylgalactosamine (D-GalNAc), galactose (D-Gal), mannose-like (D-Man-like) and sialic acid residues showed positive fluorescent labeling. A higher reactivity of Triticum vulgaris (WGA), which binds to sialic acid and/or beta-D-GlcNAc-containing residues, and Bandeiraea simplicifolia II (BS-II), which recognizes alpha and beta-D-GlcNAc units, was shown by the sucrose-fermenting strain. Ricinus communis (RCA-I), which recognizes D-Gal units in addition to both Glycine max (SBA) and Artocarpus integrifolia (Jacaline) agglutinins that bind to D-GalNAc-containing residues, reacted preferentially with the sucrose-negative strain. Canavalia ensiformis (Con A), which recognizes D-Man-like receptors, reacted with both sucrose-fermenting and non-sucrose-fermenting C. diphtheriae biotypes. However, higher interaction was observed with the non-sucrose-fermenting strain. Fluorescence of WGA binding was significantly decreased by neuraminidase treatment suggesting the presence of an exposed sialic acid moiety on C. diphtheriae surfaces. Binding assay using radiolabeled [125I]WGA essentially confirmed the lectin fluorescence studies. N-Acetylneuraminic acid moieties were detected in whole cell hydrolysates as assessed by thin-layer and gas-liquid chromatography. The data indicate differences on the cell surface saccharide ligands between the sucrose-fermenting and the non-sucrose-fermenting C. diphtheriae strains.

Chromatography, Gas↗

Lectin binding saccharides on a parasitic protozoan.

Leishmania donovani promastigotes were specifically agglutinated by concanavalin A and phytohemagglutinin P. Somatic-somatic, flagellar-somatic, and flagellar-flagellar type agglutination was observed with the lectins. Enzyme-treated promastigotes gave reduced lectin agglutination reactions. The results suggest that complex saccharide moieties are randomly distributed on the surface of this organism.

Agglutination↗

Enhanced yield of shiitake by saccharide amendment of the synthetic substrate.

Three experiments were performed to determine the effect of selected saccharides on mushroom yield and basidiome size of shiitake (Lentinula edodes) when grown on a synthetic substrate. Substrate formulations of sawdust, wheat bran, and millet were nonamended or amended with sucrose, fructose, or glucose. Addition of sucrose (0.6 to 1.2% [dry weight]) to the substrate stimulated mushroom yield by 11 to 20% or more. Addition of fructose at 1.2% and glucose at 0.6% resulted in similar yield increases. Most of the yield increase occurred on the first break. The substrate amended with 1.2% sucrose tended to have a more synchronous maturation for the second break resulting in fewer days when mushrooms were harvested.

Journal Article↗

Coaggregation between aquatic bacteria is mediated by specific-growth-phase-dependent lectin-saccharide interactions.

Coaggregating strains of aquatic bacteria were identified by partial 16S rRNA gene sequencing. The coaggregation abilities of four strains of Blastomonas natatoria and one strain of Micrococcus luteus varied with culture age but were always maximum in the stationary phase of growth. Each member of a coaggregating pair carried either a heat- and protease-sensitive protein (lectin) adhesin or a saccharide receptor, as coaggregation was reversed by sugars.

Bacterial Adhesion↗

Permeability properties of Escherichia coli outer membrane containing, pore-forming proteins: comparison between lambda receptor protein and porin for saccharide permeation.

Outer membrane permeability conferred by lambda receptor protein and porins to maltose-maltodextrins and other oligosaccharides was studied in vitro with reconstituted vesicle membranes and in vivo with mutant strains lacking either one of these proteins. The vesicle membranes reconstituted from phospholipids, lipopolysaccharide, and purified lambda receptor allowed rapid diffusion of maltose and maltose-maltodextrins of up to six glucose residues, but the membranes acted essentially as a molecular sieve for sucrose, raffinose, stachyose, and inulins of molecular weights 800, 920, and 1,380. The vesicle membranes containing porins allowed rapid diffusion of maltose but not of maltose-maltodextrins larger than maltose. The apparent transport Km values for maltose-maltodextrins of up to six glucose residues from the strain carrying lamB+ ompB (lambda receptor+, porin-) were similar (about 5 X 10(-6) M), whereas the transport Km values for maltose- and maltotriose of the strain carrying lamB ompB+ (lambda receptor-, porin+) alleles appeared to be 300 and about 20,000 X 10(-6) M. These results suggest that lambda receptor protein forms permeability pores that facilitate the diffusion of maltose-maltodextrins and function as a molecular sieve for other saccharides.

Bacterial Proteins↗

Biosynthesis of Rhizobium trifolii capsular polysaccharide: enzymatic transfer of pyruvate substitutions into lipid-bound saccharide intermediates.

The activity of capsular polysaccharide pyruvyltransferase catalyzing the pyruvylation of acidic heteropolysaccharide was measured in Rhizobium trifolii 843 and 0403 rif. This enzyme activity was determined with EDTA-treated cells, uridine diphosphate-sugar precursors, and phosphoenol [1-14C]pyruvate. Activity was measured by the incorporation of radioactivity into organic solvent-soluble glycoconjugates. Enzymatic pyruvylation of capsular polysaccharide occurred from phosphoenolpyruvate at the lipid-bound saccharide stage.

Aldehyde-Ketone Transferases↗

Epstein-Barr virus-lymphoid cell interactions. III. Effect of concanavalin A and saccharides on Epstein-Barr virus penetration.

To study some aspects of Epstein-Barr virus (EBV) penetration into target cells, the effect of concanavalin A (ConA) and various saccharides on virus infectivity and cell susceptibility to EBV infection was examined. ConA treatment of the target cells, EBV, or EBV-cell complexes was found to inhibit virus antigen expression. Several control experiments with alpha-d-methyl-mannoside elution of ConA, removal of nonfused EBV particles from the cell surface by trypsin treatment, and addition of ConA at different times postinfection were performed to define the site of ConA action on EBV infection. ConA appeared to have a dual action: (i) it inhibited EBV binding to virus receptors, and (ii) it blocked the penetration of receptor-bound virus into target cells at a trypsin-sensitive stage, thus indicating that ConA prevented the fusion of viral envelope with the target cell membrane. A high sucrose concentration (0.25 M), known to inhibit cell membrane movements, was also found to block EBV penetration at a trypsinsensitive stage, thus suggesting the implication of cell membrane movements and underlying activities (or both) in viral envelope fusion. Lower concentrations of various monosaccharides (0.12 M) did not influence EBV infection. Under conditions of ConA treatment that did not influence EBV infectivity and target cells susceptibility, ConA was able to mediate virus binding to EBV receptornegative cell lines, but no virus antigens were expressed in these cells. These observations reinforced the idea that the mere attachment of EBV to lymphoid cells is not sufficient to lead to infection. In light of the present and previously published data, we postulate the existence of a specific cellular mechanism that allows the penetration of EBV into the target (B) lymphocyte.

Antigens, Viral↗

Vanadyl(IV) complexes with saccharides. Bioactivity in osteoblast-like cells in culture.

Complexes of vanadyl(IV) with 4 monosaccharides and 5 disaccharides were tested in 2 osteoblast-like cell lines (MC3T3E1 and UMR106). Many complexes caused stimulation of UMR106 proliferation (120% basal) in the range of 2.5 to 25 micromol/L. In the nontransformed osteoblasts, some vanadyl-saccharide complexes stimulated the mitogenesis (115% basal) in the same range of concentration. The glucose and sucrose complexes were the most efficient inhibitory agents (65% and 88% of inhibition vs. basal, respectively) for tumoral cells at 100 micromol/L. The galactose and turanose complexes exerted a similar effect in the nontransformed osteoblasts. On the other hand, all the complexes promoted the phosphorylation of the extracellular regulated kinases (ERKs). All together, these results indicate that the stimulation of ERKs is not the only factor that plays a role in the proliferative effects of vanadium derivatives since some compounds were inhibitory proliferating agents. Cell differentiation was evaluated by alkaline phosphatase specific activity and collagen synthesis in UMR106 cells. All the complexes inhibited alkaline phosphatase activity, with galactose complex as the most effective compound (IC50 = 43 micromol/L). The complex with the trehalose TreVO was the most effective agent to stimulate collagen synthesis (142% basal) and glucose consumption (132% basal). A cytosolic tyrosine protein kinase and the kinase-3 of glycogen synthase seem to be involved in the stimulation of glucose consumption by vanadium derivatives. In this series, only TreVO gathered the characteristics of a good insulin mimetic and osteogenic drug. In addition, this complex was a good promoting agent of nontransformed osteoblast proliferation, whereas it inhibited tumoral osteoblasts. GluVO, the complex with glucose, was also more toxic for tumoral than for nontransformed cells. These 2 vanadium derivatives are good potential antitumoral drugs. All the results suggest that the biological effects of vanadium compounds are a complex phenomenon influenced by the complexation, the dose, and the nature of the ligands and the cells.

3T3 Cells↗

Saccharides mediate the attachment of rat macrophages to bone in vitro.

Macrophages (M phi) are multipotential cells capable of giving rise to osteoclasts and of resorbing bone. Since both of these processes are ultimately dependent upon the attachment of cells to a mineralized bone surface, we have examined in this study the mechanism by which such attachment is achieved. The data show that elicited rat peritoneal M phi bind to bone in a temperature-dependent and -saturable manner with half-maximal attachment occurring within 10 min at 37 degrees C and reaching a plateau by approximately 60 min. The kinetics of binding are essentially the same whether devitalized bone particles or viable calvaria are used as a substrate. The attachment of M phi to bone is inhibited by some sugars (e.g., N-acetyl-galactosamine, thiogalactoside, beta-lactose), fetuin and asialofetuin, and by pretreating the bone with periodate. Binding is also significantly reduced when M phi are preincubated with tunicamycin and swainsonine at nontoxic concentrations sufficient to inhibit or alter glycosylation. On the other hand, exposing the cells to neuraminidase increases the capacity of M phi to bind to bone. Collectively, our observations indicate that the attachment of M phi to bone is a highly regulated process and is mediated, at least in part, by saccharides located on both the cell and the bone surface.

Animals↗

Studies on the cell surface of zoospores and cysts of the fungus Phytophthora cinnamomi: nature of the surface saccharides as determined by quantitative lectin binding studies.

The nature of the surface saccharides of zoospores, "partially encysted zoospores" and cysts of the root-rotting fungus Phytophthora cinnamomi, has been examined by quantitative lectin binding studies. Zoospores bound concanavalin A (Con A), but did not bind any of a variety of other lectins tested. In contrast, both cysts and "partially encysted zoospores" bound soybean agglutinin (SBA) as well as Con A. This indicates that accessible alpha-D-glucosyl/alpha-D-mannosyl-containing glycoconjugates predominate at the zoospore surface, whereas both alpha-D-glucosyl/alpha-D-mannosyl and galactosyl and/or N-acetyl-D-galactosaminosyl residues are accessible at the surface of cysts and "partially encysted zoospores." Neither Ulex europeus lectin nor wheat germ agglutinin (WGA) bound to any of the three cell preparations, indicating the absence of accessible alpha-L-fucosyl and N-acetyl-D-glucosaminosyl residues.

Binding Sites↗

Pilocarpine-induced changes in the saccharide composition of the tectorial membrane and interdental cells of the organ of Corti: a study with gold-labeled lectins.

The glycoconjugates in the cytoplasm of inner ear interdental cells and those constituting the limbal tectorial membrane were identified by a post-embedding cytochemical method using low-temperature embedding in Lowicryl K4M and labeling with biotinylated lectins, goat anti-biotin antibody, rabbit anti-goat antibody, and gold-labeled protein A in control animals, and after the systemic injection of pilocarpine. The lectins used were ConA, PHA-E, PSA, RCA, SBA, Succ-WGA, UEA, and WGA. In control animals, a semiquantitive analysis of gold particles showed that Succ-WGA produced the strongest labeling on the tectorial membrane, followed by SBA, ConA, WGA, RCA, PHA-E, and PSA. The lowest values were obtained with UEA. The cytoplasm of the interdental cells was also labeled with all the lectins, but the number of particles/microns2 was lower than on the tectorial membrane. The concentration of gold particles on the limbal tectorial membrane in pilocarpine-treated animals was higher than in control animals for some lectins (RCA, PSA, UEA) but lower for others (WGA, SBA, PHA-E, Succ-WGA). The changes in the labeling pattern of the cytoplasm of the interdental cells paralleled those in the tectorial membrane. These results demonstrate that the saccharide composition of the limbal tectorial membrane can be modified by systemic injection of pilocarpine. This action may take place through a change in either the secretion rate or the amount of some glycoconjugates by the interdental cells.

Acrylic Resins↗

Complex saccharide metabolism in cystic fibrosis fibroblasts.

There are several reports of secretory and other abnormalities present in cultured fibroblasts from patients with cystic fibrosis (CF). We have, therefore, investigated aspects of complex saccharide synthesis and secretion by such cells compared with fibroblasts derived from heterozygous (HZ) parents and from normal (N) children. The main glycosaminoglycans produced by skin fibroblasts during in vitro culture were hyaluronic acid, heparan sulfates, and dermatan sulfate-like materials. Using double-label experiments with D-[3H]- or [14c]glucosamine and analyzing the products by ion exchange chromatography, it was shown for five CF, two HZ, and four N lines that these polysaccharides were secreted into the medium in approximately similar proportions to each other. Moreover, experiments in which three CF, nine HZ, and three N lines were grown in log phase for up to 5 days in the presence of [35S]sulfate and [3H]glucosamine indicate that, during such a period, CF fibroblasts do not secrete complex carbohydrates at rates significantly different from N or HZ cells. Neither do such cells shown an abnormal intracellular accumulation of complex carbohydrates. The latter observation was further confirmed by preparing whole cell autoradiographs during growth of six CF, two HZ, and three N lines in the presence of D-[3H]glucosamine and, subsequently, after addition of unlabeled medium.

Autoradiography↗