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PubMed1997

Structure of the main saccharide chain in the acrosome reaction-inducing substance of the starfish, Asterias amurensis.

The structure of the main saccharide chain of the acrosome reaction-inducing substance in the egg jelly coat of the starfish, Asterias amurensis, is composed of the following pentasaccharide repeating units (Structure I). A polymer consisting of 10-11 repeating units has been observed to induce the acrosome reaction in starfish sperm at high calcium concentrations. [STRUCTURE I:see text] The identities and linkage positions of constituent sugars were established using sugar, methylation, and sulfate analyses together with one- and two-dimensional nmr spectroscopy. The structure was supported by the data obtained for desulfation products and the Smith degradation of the polysaccharide.

Acrosome↗
PubMed1999

Thermodynamic studies of saccharide binding to artocarpin, a B-cell mitogen, reveals the extended nature of its interaction with mannotriose [3,6-Di-O-(alpha-D-mannopyranosyl)-D-mannose].

The thermodynamics of binding of various saccharides to artocarpin, from Artocarpus integrifolia seeds, a homotetrameric lectin (M(r) 65, 000) with one binding site per subunit, was determined by isothermal titration calorimetry measurements at 280 and 293 K. The binding enthalpies, DeltaH(b), are the same at both temperatures, and the values range from -10.94 to -47.11 kJ mol(-1). The affinities of artocarpin as obtained from isothermal titration calorimetry are in reasonable agreement with the results obtained by enzyme-linked lectin absorbent essay, which is based on the minimum amount of ligand required to inhibit horseradish peroxidase binding to artocarpin in enzyme-linked lectin absorbent essay (Misquith, S., Rani, P. G., and Surolia, A. (1994) J. Biol. Chem. 269, 30393-30401). The interactions are mainly enthalpically driven and exhibit enthalpy-entropy compensation. The order of binding affinity of artocarpin is as follows: mannotriose>Manalpha3Man>GlcNAc(2)Man(3)>MealphaMan>Man>M analpha6Man> Manalpha2Man>MealphaGlc>Glc, i.e. 7>4>2>1.4>1>0.4>0.3>0.24>0.11. The DeltaH for the interaction of Manalpha3Man, Manalpha6Man, and MealphaMan are similar and 20 kJ mol(-1) lower than that of mannotriose. This indicates that, while Manalpha3Man and Manalpha6Man interact with the lectin exclusively through their nonreducing end monosaccharide with the subsites specific for the alpha1,3 and alpha1,6 arms, the mannotriose interacts with the lectin simultaneously through all three of its mannopyranosyl residues. This study thus underscores the distinction in the recognition of this common oligosaccharide motif in comparison with that displayed by other lectins with related specificity.

B-Lymphocytes↗
PubMed2000

Inhibition of selectin-mediated cell adhesion and prevention of acute inflammation by nonanticoagulant sulfated saccharides. Studies with carboxyl-reduced and sulfated heparin and with trestatin a sulfate.

Selectins play a major role in the inflammatory reaction by initiating neutrophil attachment to activated vascular endothelium. Some heparin preparations can interact with L- and P-selectin; however, the determinants required for inhibiting selectin-mediated cell adhesion have not yet been characterized. We now report that carboxyl-reduced and sulfated heparin (prepared by chemical modifications of porcine intestinal mucosal heparin leading to the replacement of carboxylates by O-sulfate groups) and trestatin A sulfate (obtained by sulfation of trestatin A, a non-uronic pseudo-nonasaccharide extracted from Streptomyces dimorphogenes) exhibit strong anti-P-selectin and anti-L-selectin activity while lacking antithrombin-mediated anticoagulant activity. In vitro experiments revealed that both compounds inhibited P-selectin- and L-selectin-mediated cell adhesion under laminar flow conditions. Moreover, carboxyl-reduced and sulfated heparin and trestatin A sulfate were also active in vivo, as assessed by experiments showing 1) that microinfusion of trestatin A sulfate reduced by 96% leukocyte rolling along rat mesenteric postcapillary venules and 2) that both compounds inhibited (by 58-81%) neutrophil migration into thioglycollate-inflamed peritoneum of BALB/c mice. These results indicate that nonanticoagulant sulfated saccharides targeted at P-selectin and L-selectin may have therapeutic potential in inflammatory disorders.

Antibodies↗
PubMed2001

The crystal structure of a novel mammalian lectin, Ym1, suggests a saccharide binding site.

Ym1, a secretory protein synthesized by activated murine peritoneal macrophages, is a novel mammalian lectin with a binding specificity to GlcN. Lectins are responsible for carbohydrate recognition and for mediating cell-cell and cell-extracellular matrix interactions in microbes, plants, and animals. Glycosaminoglycan heparin/heparan sulfate binding ability was also detected in Ym1. We report here the three-dimensional structure of Ym1 at 2.5-A resolution by x-ray crystallography. The crystal structure of Ym1 consists of two globular domains, a beta/alpha triose-phosphate isomerase barrel domain and a small alpha + beta folding domain. A notable electron density of sugar is detected in the Ym1 crystal structure. The saccharide is located inside the triose-phosphate isomerase domain at the COOH terminal end of the beta-strands. Both hydrophilic and hydrophobic interactions are noted in the sugar-binding site in Ym1. Despite the fact that Ym1 is not a chitinase, structurally, Ym1 shares significant homology with chitinase A of Serratia marcescens. Ym1 and chitinase A have a similar carbohydrate binding cleft. This study provides new structure information, which will lead to better understanding of the biological significance of Ym1 and its putative gene members.

Amino Acid Sequence↗
PubMed2004

Various non-digestible saccharides increase intracellular calcium ion concentration in rat small-intestinal enterocytes.

We have previously shown that non-digestible saccharides (NDS) stimulate intestinal Ca absorption via tight junctions. However, the cellular mechanisms activated by the NDS are not yet known. We investigated the effects of four NDS, difructose anhydride (DFA) III, DFAIV, fructo-oligosaccharides, and maltitol, on intracellular Ca signalling in isolated rat small-intestinal enterocytes. The changes in intracellular Ca(2+) concentration were measured before and after the addition of capric acid (7.5 or 15 mmol/l, a positive control), glycerol, or each NDS (1 or 10 mmol/l) to fura-2-loaded enterocytes. Treatment with capric acid or each NDS caused an immediate and dose-dependent rise in intracellular Ca(2+) concentration. Mechanical and osmotic stimulation achieved by adding glycerol had no effect on intracellular Ca(2+) concentration. The intracellular Ca(2+) concentration in enterocytes treated with DFAIII and fructo-oligosaccharides reached a peak level at about 30 s after stimulation, but those treated with DFAIV and maltitol showed further increases after the initial rapid rise. The maximum change in intracellular Ca(2+) concentration obtained by the application of maltitol was higher than that of DFAIII at 10 mmol/l. These findings suggest that each of the four NDS directly stimulates rat enterocytes, and increases intracellular Ca(2+) concentration. Thus, molecular structure may be more important than the size of the NDS in the induction of Ca signalling in the cells.

Animals↗
PubMed2004

Reaction of peroxynitrite with hyaluronan and related saccharides.

The effects of peroxynitrite on hyaluronan has been studied by using an integrated spectroscopical approach, namely electron paramagnetic resonance (EPR), nuclear magnetic resonance (NMR), and mass spectrometry (MS). The reaction has been performed with the polymer, the tetrasaccharide oligomer as well as with the monosaccharides N-acetylglucosamine and glucuronic acid. The outcome of the presence of molecular oxygen and carbon dioxide has been also evaluated. Although 1H-NMR and ESI-MS experiments did not revealed peroxynitrite-mediated modification of hyaluronan as well as of related saccharides, from spin-trapping EPR experiments it was concluded that peroxynitrite induce the formation of C-centered carbon radicals, most probably by the way of its hydroxyl radical-like reactivity. These EPR data support the oxidative pathway involved in the degradation of hyaluronan, a probable event in the development and progression of rheumatoid arthritis.

Acetylglucosamine↗
PubMed1979

Distribution of cell surface saccharides on pancreatic cells. I. General method for preparation and purification of lectins and lectin-ferritin conjugates.

We describe here a simple, general procedure for the purification of a variety of lectins, and for the preparation of lectin-ferritin conjugates of defined molar composition and binding properties to be used as probes for cell surface saccharides. The technique uses a "universal" affinity column for lectins and their conjugates, which consists of hog sulfated gastric mucin glycopeptides covalently coupled to agarose. The procedure involes: (a) purification of lectins by chromatography of aqueous extracts of seeds or other lectin-containing fluids over the affinity column, followed by desorption of the desired lectin with its hapten suge; (b) iodination of the lectin to serve as a marker during subsequent steps; (c) conjugation of lectin to ferritin with glutaraldehyde; (d) collection of active lectin-ferritin conjugates by affinity chromatography; and (e) separation of monomeric lectin-ferritin conjugates from larger aggregates and unconjugated lectin by gel chromatography. Based on radioactivity and absorbancy at 310 nm for lectin and ferritin, respectively, the conjugates consist of one to two molecules of lectin per ferrritin molecule. Binding studies of native lectins and their ferritin conjugates to dispersed pancreatic acinar cells showed that the conjugation procedure does not significantly alter either the affinity constant of the lectin for its receptor on the cell surface or the number of sites detected.

Binding Sites↗
PubMed1979

Distribution of cell surface saccharides on pancreatic cells. II. Lectin-labeling patterns on mature guinea pig and rat pancreatic cells.

The surface saccharide composition of collagenase-dispersed pancreatic cells from adult guinea pig and rat glands was examined by using eight lectins and their ferritin conjugates: Concanavalin A (ConA); Lens culinaris (LCL); Lotus tetragonolobus (LTL); Ricinus communis agglutinins I and II (RCA I, RCA II); Soybean agglutinin (SBA); Ulex europeus lectin (UEL); and wheat germ agglutinin (WGA). Binding studies of iodinated lectins and lectin-ferritin conjugates both revealed one population of saturable, high-affinity receptor sites on the total cell population (approximately 95% acinar cells). Electron microscopy, however, revealed differences in lectin-ferritin binding to the plasmalemma of acinar, centroacinar, and endocrine cells. Whereas acinar cells bound heavily all lectin conjugates, endocrine and centroacinar cells were densely labeled only by ConA, LCL, WGA, and RCA I, and possessed few receptors for LTL, UEL, and SBA. Endocrine and centroacinar cells could be differentiated from each other by using RCA II, which binds to centroacinar cells but not to endocrine cells. Some RCA II receptors appeared to be glycolipids because they were extracted by ethanol and chloroform-methanol in contrast to WGA receptors which resisted solvent treatment but were partly removed by papain digestion. RCA I receptors were affected by neither treatment. The apparent absence of receptors for SBA on endocrine and centroacinar cells, and for RCA II on endocrine cells, was reversed by neuraminidase digestion, which suggested masking of lectin receptors by sialic acid. The absence of LTL and UEL receptors on endocrine and centroacinar cells was not reversed by neuraminidase. We suggest that the differential lectin-binding patterns observed on acinar, centroacinar, and endocrine cells from the adult pancreas surface-carbohydrate-developmental programs expressed during morphogenesis and cytodifferentiation of the gland.

Animals↗
PubMed1980

Development of cell surface saccharides on embryonic pancreatic cells.

Using a battery of seven lectin-ferritin conjugates as probes for cell surface glycoconjugates, we have studied the pattern of plasmalemmal differentiation of cells in the embryonic rat pancreas from day 15 in utero to the early postpartum stage. Our results indicate that differentiation of plasmalemmal glycoconjugates on acinar, endocrine, and centroacinar cells is temporally correlated with development and is unique for each cell type, as indicated by lectin-ferritin binding. Specifically, (a) expression of adult cell surface saccharide phenotype can be detected on presumptive acinar cells as early as 15 d in utero, as indicated by soybean agglutinin binding, and precedes development of intracellular organelles characteristic of mature acinar cells; (b) maturation of the plasmalemma of acinar cells is reached after intracellular cytodifferentiation is completed, as indicated by appearance of Con A and fucoselectin binding sites only at day 19 of development; conversely, maturation of the endocrine cell plasmalemma is accompanied by "loss" (masking) of ricinus communis II agglutinin receptors; and (c) binding sites for fucose lectins and for soybean agglutinin are absent on endocrine and centroacinar cells at all stages examined. We conclude that acinar, centroacinar, and endocrine cells develop from a common progenitor cell(s) whose plasmalemmal carbohydrate composition resembles most closely that of the adult centroacinar cell. Finally, appearance of acinar lumina beginning at approximately 17 d in utero is accompanied by differenetiation of apical and basolateral plasmalemmal domains of epithelial cells, as indicated by enhanced binding of several lectin-ferritin conjugates to the apical plasmalemmal, a pattern that persists from this stage through adult life.

Animals↗
PubMed1984

Purification and characterization of a mannose-containing disaccharide obtained from human pregnancy urine. A new immunoregulatory saccharide.

Endogenous mammalian lectin-like sugar-binding molecules have been previously described that have immunoregulatory properties. Further, the addition of defined simple saccharides to lymphocyte cultures has been shown to inhibit a variety of in vitro lymphocyte functions, presumably because these sugars are able to compete with the binding of endogenous lectins to critical membrane receptors. In this report, we describe the isolation and characterization of a D-mannose-containing disaccharide in human pregnancy urine that inhibits the proliferative response of human T lymphocytes. The inhibitory disaccharide was purified to homogeneity by sequential steps including affinity chromatography on immobilized concanavalin A and molecular sizing on Sephadex G-75 and then Fractogel 40S columns, with final purification on high-performance thin-layer chromatography. By mass spectrometry of the purified material as its permethylated derivative, the deduced structure of this compound was alpha-D-Manp 1-6-D-Man. To confirm that this disaccharide was in fact immunosuppressive, an identical disaccharide was prepared by sequential digestion of yeast cell wall polysaccharide. The urinary and yeast disaccharides had identical immunosuppressive properties. It has been previously reported that D-mannose is inhibitory for antigen-specific proliferative assays in the range of 10-50 mM. The purified alpha-D-Manp 1-6-D-Man disaccharide was inhibitory at 100-fold-lower concentrations. Further, while D-mannose inhibits T cell proliferation when added at anytime up to 24 h before harvest of a 6-d lymphocyte culture, alpha-D-Manp 1-6-D-Man disaccharide was inhibitory only if added at the initiation of culture and had no inhibitory effect if added just 24 h later. These data support the concept that simple sugar compounds can exhibit marked immunoregulatory activity in vitro. The impact of these molecules on the regulation of immune responses in vivo is unknown, as is their precise mechanism of action, but structural and chemical identification should now permit a detailed analysis of these issues.

Chromatography, Affinity↗
PubMed1988

Biology of Giardia lamblia. Detection of N-acetyl-D-glucosamine as the only surface saccharide moiety and identification of two distinct subsets of trophozoites by lectin binding.

Lectins and glycosidases of known sugar specificity were used as probes to analyze the surface carbohydrate moieties of G. lamblia trophozoites and in particular to determine whether chitin or oligomeric D-GlcNAc is present in the trophozoite form of the parasite as well as on the cyst. Of 13 lectins with varying sugar specificity, only D-GlcNAc-specific lectins bound specifically to the trophozoite surface as determined by light microscopy and EM. A striking finding was the identification of two distinct subsets of trophozoites, distinguished by reactivity with WGA and detected by light microscopy and EM as well as by flow cytometry. Unlike the cyst wall, the trophozoite D-GlcNAc residues were resistant to chitinase treatment. In contrast N-acetyl-beta-D-glucosaminidase abolished WGA binding suggesting that the lectin binds to terminal beta-linked D-GlcNAc residues. These residues were identified as being present on surface glycoproteins by Western blotting of parasite membrane proteins using WGA as a probe. This study identifies D-GlcNAc as the only saccharide moiety detectable by lectin binding on the surface of G. lamblia trophozoites and demonstrates that in contrast to the cyst, chitin is not present in the trophozoite. In addition two distinct subsets of trophozoites were identified based on reactivity with WGA and may represent varying stages of differentiation from trophozoite to cyst.

Acetylglucosamine↗
PubMed1977

Lyoluminescence dosimetry with some saccharides.

Lyoluminescent properties of mannose, glucose monohydrate, sucrose and trehalose dihydrate were investigated from the point of view of suitability as dosimetric materials in a new system of solid state dosimetry. Distilled water was used as a solvent. With a reader equipped with an uncooled PM tube it was possible to measure doses of X- and gamma-rays in the range from a few rad to about 100 krad. Various experimental factors which could affect the dose measurements using lyoluminescence are discussed, including the energy response for X-rays. Some preliminary information on the response of saccharides to fast neutrons is also included.

Disaccharides↗
PubMed2002

Absorption of anti-blood group A antibodies on P-selectin glycoprotein ligand-1/immunoglobulin chimeras carrying blood group A determinants: core saccharide chain specificity of the Se and H gene encoded alpha1,2 fucosyltransferases in different host cells.

To specifically eliminate recipient anti-blood group ABO antibodies prior to ABO-incompatible organ or bone marrow transplantation, an efficient absorber of ABO antibodies has been developed in which blood group determinants may be carried at high density and by different core saccharide chains on a mucin-type protein backbone. The absorber was made by transfecting different host cells with cDNAs encoding a P-selectin glycoprotein ligand-1/mouse immunoglobulin G(2b) chimera (PSGL-1/mIgG(2b)), the H- or Se-gene encoded alpha1,2-fucosyltransferases (FUT1 or FUT2) and the blood group A gene encoded alpha1,3 N-acetylgalactosaminyltransferase (alpha1,3 GalNAcT). Western blot analysis of affinity-purified recombinant PSGL-1/mIgG(2b) revealed that different precursor chains were produced in 293T, COS-7m6, and Chinese hamster ovary (CHO)-K1 host cells coexpressing FUT1 or FUT2. FUT1 directed expression of H type 2 structures mainly, whereas FUT2 preferentially made H type 3 structures. None of the host cells expressing either FUT1 or FUT2 supported expression of H type 1 structures. Furthermore, the highest A epitope density was on PSGL-1/mIgG2(2b) made in CHO-K1 cells coexpressing FUT2 and the alpha1,3 GalNAcT. This PSGL-1/mIgG(2b) was used for absorption of anti-blood group A antibodies in human blood group O serum. At least 80 times less A trisaccharides on PSGL-1/mIgG(2b) in comparison to A trisaccharides covalently linked to macroporous glass beads were needed for the same level of antibody absorption. In conclusion, PSGL-1/mIgG(2b), if substituted with A epitopes, was shown to be an efficient absorber of anti-blood group A antibodies and a suitable model protein for studies on protein glycosylation.

ABO Blood-Group System↗
PubMed1993

Investigation of sucrose synthase from rice for the synthesis of various nucleotide sugars and saccharides.

The unique character of the plant glucosyltransferase sucrose synthase, to catalyse in vitro the synthesis and cleavage of sucrose under appropriate conditions, can be exploited for the enzymatic synthesis of carbohydrates. The present paper describes the potential utilization of sucrose synthase from rice for the enzymatic synthesis of activated sugars and saccharides. In the cleavage reaction of sucrose, the nucleoside diphosphates can be used in the order UDP > TDP > ADP > CDP > GDP to obtain the corresponding activated glucoses. In batch reactions, > 90% conversion of UDP and TDP could be achieved. Substituting different di- and trisaccharides for sucrose in the cleavage reaction with UDP 2-deoxysucrose was the most promising substrate. Sucrose synthase was combined with UDP-galactose 4'-epimerase and beta 1-4 galactosyltransferase to synthesize N-acetyllactosamine with in situ regeneration of UDP-glucose. In the synthesis reaction of sucrose synthase, different donor (UDP-sugars) and acceptor substrates were investigated. UDP-N-acetylglucosamine and UDP-xylose could be used in combination with fructose as acceptor. D-Xylulose, D-tagatose, D-lyxose, D-psicose, L-sorbose, D-mannose, L-arabinose, 1,6 anhydroglucose, lactulose, raffinose and isomaltulose can serve as acceptors for UDP-glucose.

Disaccharides↗
PubMed1995

Lectin recognition of host-like saccharide motifs in streptococcal cell wall polysaccharides.

Viridans streptococci that participate in the microbial colonization of teeth have cell wall polysaccharides composed of linear phosphodiester-linked hexa- or heptasaccharide repeating units, each containing a host-like disaccharide motif, either Gal beta 1-->3GalNAc or GalNAc beta 1-->3Gal. Whereas strains with GalNAc beta 1-->3Gal-containing polysaccharides co-aggregated with streptococci that possess GalNAc-sensitive lectins, strains with either host-like motif co-aggregated with Actinomyces spp. The latter interactions reflected the specificity of Actinomyces spp. lectins for common features of Gal beta 1-->3GalNAc and GalNAc beta 1-->3Gal. Thus, alpha-linked glycosides of both disaccharides were much more potent inhibitors of co-aggregation than Gal or GalNAc. Six non-bacterial lectins also reacted with the streptococcal polysaccharides. In general, precipitation of each lectin with each polysaccharide involved binding of Gal or GalNAc within the host-like motifs, but not saccharides outside these regions. The lectins of Ricinus communis, Abrus precatorius, Codium fragile and Agaricus bisporus were most reactive with the Gal beta 1-->3GalNAc-containing polysaccharides, the Wisteria floribunda lectin with the GalNAc beta 1-->3Gal-containing polysaccharides and the Bauhinia purpurea lectin with polysaccharides containing either disaccharide. Thus, lectin recognition of the streptococcal cell wall polysaccharides involved either the common or specific sides of the Gal beta 1-->3GalNAc and GalNAc beta 1-->3Gal motifs present within these molecules.

Actinomyces↗
PubMed1997

Synthesis of a new nanomolar saccharide inhibitor of lymphocyte adhesion: different polylactosamine backbones present multiple sialyl Lewis x determinants to L-selectin in high-affinity mode.

Lymphocyte infiltration is a hallmark of acute rejections in solid organ transplants, such as cardiac allograft. We have previously shown that lymphocyte extravasation to cardiac grafts undergoing rejection is largely due to interactions between lymphocyte L-selectin and its sialyl Lewis x (sLex) decorated ligands. Our previous work demonstrated further that an enzymatically synthetized tetravalent sLex glycan of a branched polylactosamine backbone is a highly efficient inhibitor of L-selectin-dependent lymphocyte adhesion to graft endothelium. To improve the availability of multivalent sLex glycans for anti-inflammatory indications, we now report enzymatic synthesis of another tetravalent sLex glycan that can be potentially produced on a large scale, and show that even the new saccharide is a nanomolar inhibitor of L-selectin-dependent lymphocyte adhesion. The novel antagonist is sLex beta 1-3' (sLex beta 1-6') LacNAc beta 1-3' (sLex beta 1-6') LacNAc beta 1-3' (sLex beta 1-6') LacNAc (8) (where LacNAc is the disaccharide Gal beta 1-4GlcNac and sLex is the tetrasaccharide Neu5Ac alpha 2-3Gal beta 1-4 (Fuc alpha 1-3) GlcNAc). Its five-step synthesis was started from the octameric polylactosamine LacNAc beta 1-3' (GlcNAc beta 1-6') LacNAc beta 1-3' (GlcNAc beta 1-6') LacNAc (3), which in turn is accessible in one step from the hexasaccharide LacNAc beta 1-3'LacNAc beta 1-3'LacNAc. Importantly, the hexasaccharide primer has been synthesized chemically (Alais and Veyrieres, Tetrahedron Lett., 24, 5223, 1983). Hence, our data outline a route to glycan 8, consisting of a combination of chemical and enzymatic methods of oligosaccharide synthesis. In addition, our data show that polylactosamine backbones are able to present multiple sialyl Lewis x determinants to L-selectin in high-affinity mode, without a requirement for uniqueness in the backbone structure.

Amino Sugars↗
PubMed2006

Interaction profile of galectin-5 with free saccharides and mammalian glycoproteins: probing its fine specificity and the effect of naturally clustered ligand presentation.

Cell-surface glycans are functional docking sites for tissue lectins such as the members of the galectin family. This interaction triggers a wide variety of responses; hence, there is a keen interest in defining its structural features. Toward this aim, we have used enzyme-linked lectinosorbent (ELLSA) and inhibition assays with the prototype rat galectin-5 and panels of free saccharides and glycoconjugates. Among 45 natural glycans tested for lectin binding, galectin-5 reacted best with glycoproteins (gps) presenting a high density of Galbeta1-3/4GlcNAc (I/II) and multiantennary N-glycans with II termini. Their reactivities, on a nanogram basis, were up to 4.3 x 10(2), 3.2 x 10(2), 2.5 x 10(2), and 1.7 x 10(4) times higher than monomeric Galbeta1-3/4GlcNAc (I/II), triantennary-II (Tri-II), and Gal, respectively. Galectin-5 also bound well to several blood group type B (Galalpha1-3Gal)- and A (GalNAcalpha1-3Gal)-containing gps. It reacted weakly or not at all with tumor-associated Tn (GalNAcalpha1-Ser/Thr) and sialylated gps. Among the mono-, di-, and oligosaccharides and mammalian glycoconjugates tested, blood group B-active II (Galalpha1-3Gal beta1-4GlcNAc), B-active IIbeta1-3L (Galalpha1-3Galbeta1-4GlcNAc beta1-3Galbeta1-4Glc), and Tri-II were the best. It is concluded that (1) Galbeta1-3/4GlcNAc and other Galbeta1-related oligosaccharides with alpha1-3 extensions are essential for binding, their polyvalent form in cellular glycoconjugates being a key recognition force for galectin-5; (2) the combining site of galectin-5 appears to be of a shallow-groove type sufficiently large to accommodate a substituted beta-galactoside, especially with alpha-anomeric extension at the non-reducing end (e.g., human blood group B-active II and B-active IIbeta1-3L); (3) the preference within beta-anomeric positioning is Galbeta1-4 > or = Galbeta1-3 > Galbeta1-6; and (4) hydrophobic interactions in the vicinity of the core galactose unit can enhance binding. These results are important for the systematic comparison of ligand selection in this family of adhesion/growth-regulatory effectors with potential for medical applications.

Amino Acid Sequence↗
PubMed2004

Ingestion of guar gum hydrolysate, a soluble and fermentable nondigestible saccharide, improves glucose intolerance and prevents hypertriglyceridemia in rats fed fructose.

Fructose feeding provides a dietary model of insulin resistance accompanied by hypertriglyceridemia. We examined the effects of guar gum hydrolysate (GGH), a soluble and fermentable nondigestible saccharide with low viscosity, on glucose intolerance and hypertriglyceridemia in rats fed high-fructose diets. Rats were fed either a dextrin-based or a fructose-based diet with or without GGH (75 g/kg) for 30 d. Oral glucose tolerance tests (OGTTs) were performed 0, 14, and 28 d after feeding. High-fructose feeding negatively affected glucose tolerance on d 14 and 28. The addition of GGH to the diets improved glucose intolerance on d 28. Fructose feeding induced hyperinsulinemia after an oral glucose load; this was also improved by GGH on d 28. The glycogen concentration in the gastrocnemius muscles of rats was lowered by dietary fructose, and GGH supplementation abolished this decrease. Triglycerides in the plasma and livers of rats fed fructose diets were elevated, and the increases were ameliorated by supplemental GGH. Regardless of the type of carbohydrate, GGH enlarged the cecum and increased the cecal SCFA pools. In conclusion, supplemental feeding of GGH to rats improved the glucose intolerance and hypertriglyceridemia induced by a high-fructose diet. Possible mediators of these beneficial effects of GGH are the SCFAs produced by microbial fermentation of GGH in the large intestine.

Animals↗