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At least 19 recordsLinked to original sources
PubMed2000

[Enzymatic synthesis of saccharide and saccharide alcohol fatty acid esters].

Conditions for esterification in tert-butanol using fatty acid as acy1 donor and saccharides or saccharide alcohols as acy1 acceptors, immobilized lipase from Candida sp. 1619 as biocatalyst were investigated. Optimal temperature and pH for esterication were 40 degrees C-45 degrees C and 5.5-7.5, respectively. Among the 13 acy1 donors compared, the best ones are the linoleic acid and oleic acid. The similar conversion degree was obtained when using saturated fatty acids with carbon chain length from C8 to C22. Among the 23 saccharides and saccharide alcohols compared, D-fructose, D-Xylose, trehalose, D-sorbitol, xylitol, mannitol isopropyidoneglucofruranose and alpha-methylglucopyranoside showed much higher esterification degree than other acy1 acceptors. In addition, the reaction degree of saccharide alcohols were substantially higher than that of the corresponding saccharides. The conversion was enhanced greatly when the molar ratio of acy1 donor to acy1 acceptor was higher than 2 to 1. In the case of using sorbitol and loeic acid as substrates, the reaction was carried out in 100 ml conical flask and the reaction system consisted of 3.0 mmol oleic acid(0.85 g), 0.2 mmol sorbitol(0.036 g), 3 mL tert-butanol, 30 mg immobilized lipase(600 u), shaken at 40 degrees C. After reaction for 48 h, more than 90% of sorbitol was esterified based on equal molar of substrates. The products were identified TLC as monoester and diester.

Candida↗
PubMed1993

Steric presentation and recognition of the saccharide chains of glycolipids at the cell surface: favoured conformations of the saccharide-lipid linkage calculated using molecular mechanics (MM3).

The orientation of the saccharide moiety of glycolipids at the membrane surface is determined by an interplay of different steric factors, e.g. the conformation of the saccharide chain, the conformation of the saccharide-lipid linkage and restrictions due to the membrane surface. In the present study the preferred conformations of the saccharide-lipid linkages of glucosylceramides with normal and hydroxy fatty acids and glucosyldiglycerides with acyl and alkyl chains were studied using molecular mechanics (MM3). The populations of different conformers were calculated on the basis of relaxed energy maps. Calculations on glucosylceramides at a dielectric constant (epsilon) of 4 showed three dominating conformers: phi/psi/theta 1 = +sc/ap/-sc (global energy minimum), /-sc/ap and +sc/ap/ap, respectively. In sphingolipids the +sc rotamer of theta 1 is disfavoured due to a Hassel-Ottar interaction involving the sphingosine O1 and O3 oxygen atoms. alpha-O Hydroxylation of the fatty acid does not significantly affect the conformational preferences of the saccharide-ceramide linkage at epsilon-values relevant for biomembranes. In glycoglycerolipids the global energy minimum is shifted to the phi/psi/theta 1 = +sc/ap/ap conformation. For glycolipids located in membranes additional steric restrictions are imposed by the surrounding lipid layer. These restrictions in the steric presentation appear to be of crucial significance for the selective recognition and crypticity of glycolipids in membranes.

Carbohydrate Conformation↗
PubMed1995

Water-soluble poly(acrylamide-allylamine) derivatives of saccharides for protein-saccharide binding studies.

Water-soluble poly(acrylamide-allylamine) copolymers containing covalently bound amino groups, prepared by copolymerization of acrylamide and allylamine, can be used as general carriers for coupling of different types of saccharides or saccharide derivatives. The water-soluble macromolecular carbohydrate derivatives can be easily labelled and used in various solid-phase techniques to study protein-saccharide interaction. Two types of coupling reaction were used to prepare polyacrylamide derivatives of saccharides: reductive amination was applied to couple the reducing disaccharides and a carbodiimide reaction was used to couple heparin via its carboxyl groups to the amino groups of the poly(acrylamide-allylamine) derivative. Peroxidase labelled or biotinylated derivatives were shown to be useful in studies on the binding properties of lectins and proteins from boar seminal plasma.

Acrylic Resins↗
PubMed2004

Fluorophore appended saccharide cyclophane: self-association, fluorescent properties, heterodimers with cyclodextrins, and cross-linking behavior with peanut agglutinin of dansyl-modified saccharide cyclophane.

A saccharide cyclophane bearing an environment-sensitive fluorophore (1) was prepared by introducing not only three branches with a terminal galactose residue but also one with a dansyl moiety into a tetraaza[6.1.6.1]paracyclophane skeleton. Self-association behavior of the dansyl-appended saccharide cyclophane was characterized in aqueous media by fluorescence spectroscopy and dynamic light scattering measurements. At least in the concentrations below 1.0 x 10(-5) M, saccharide cyclophane 1 existed in a monomeric state, whereas it tended to form self-aggregated complexes in the higher concentration. Solvent polarity dependency on the emission spectra of 1 was examined by fluorescence spectroscopy. With increasing dioxane contents in dioxane/water solvents, the fluorescence intensity originating from the dansyl moiety of 1 increased along with a concomitant blue shift of the fluorescence maximum (lambda(em)). In the monomeric state of 1 in water, the dansyl moiety of 1 was not fully included into its cyclophane cavity but partially exposed to the bulk aqueous phase. In the higher concentration ranges in an aggregate state, however, the dansyl group of 1 was located in the apolar cyclophane cavity whose microenvironment was equivalent to the polarity of 1-butanol evaluated on the basis of a correlation between lambda(em) and solvent polarity. This indicates an intermolecular inclusion of the dansyl moiety within the cyclophane. When cyclodextrin (CD) was mixed with 1, the dansyl group of 1 was bound to an internal cavity of CD such as gamma-CD, beta-CD, 6-O-alpha-glucosyl-beta-CD, and 6-O-alpha-maltosyl-beta-CD with binding constants of 7.5 x 10(2), 7.8 x 10(2), 7.7 x 10(2), and 6.0 x 10(2) M(-1), respectively. Such a supramolecular assembling of dansyl-modified cyclophane 1 and CDs caused changes of the fluorescence spectra as well as appearance of induced CD bands in aqueous media. Furthermore, saccharide cyclophane 1 was selectively bound to peanut agglutinin (PNA), galactoside-binding lectin, which was readily monitored by a visible turbidity of the solution due to a cross-linking agglutination of these components, as well as by fluorescence spectroscopy.

Journal Article↗
PubMed1974

The distribution and asymmetry of mammalian cell surface saccharides utilizing ferritin-conjugated plant agglutinins as specific saccharide stains.

The preparation, properties, and some applications of ferritin conjugates of two plant agglutinins, concanavalin A and Ricinus communis agglutinin, are reported. These conjugates serve as specific electron-dense stains for cell- and membrane-bound saccharide residues of the alpha-D-mannopyranosyl and beta-D-galactopyranosyl configurations, respectively, and as examples of a wide range of ferritin-plant agglutinin conjugates useful as high resolution saccharide stains. By using a technique for preparing flattened membrane specimens, it was found with a variety of mammalian cell plasma membranes (lymphocyte, lymphoma, and myeloma and normal, spontaneously and virally transformed fibroblasts) that the ferritin conjugates were localized exclusively to the exterior face of the membrane, with essentially none found on the cytoplasmic face. On the exterior face the topographical distribution of ferritin conjugates appeared to be random. The asymmetrical distribution of saccharide residues to the outer membrane face can be explained by an "assembly line" process whereby new plasma membrane is made from intracellular precursor membranes. It also suggests that the saccharide-containing components of the plasma membrane do not rotate at any appreciable rate from one membrane surface to the other.

Animals↗
PubMed2000

Lanthanide-saccharide chemistry: synthesis and characterisation of Ce(III)-saccharide complexes.

A series of nine Ce(III) complexes has been synthesised with seven different monosaccharides (D-glucose, D-fructose, D-galactose, D-mannose, L-sorbose, D-ribose and D-xylose) and two different disaccharides (D-maltose and L-lactose), and these have been characterised with various analytical, spectral, magnetic and electrochemical techniques. The NMR studies have highlighted some interesting features about the metal-ion-binding pattern of the saccharides. Some additional coordination has been proposed along with the chelating groups in the saccharide molecules, based on the shifts in 13C NMR spectra. On the other hand, solution absorption studies and solid-state magnetic susceptibilities have indicated the contribution from the d-character to the spectral features to some extent.

Cerium↗
PubMed1996

Metal-saccharide chemistry and biology: saccharide complexes of zinc and their effect on metallothionein synthesis in mice.

Monosaccharide (D-Fru, D-Gal, D-Glc, D-Xyl, and D-Rib) and disaccharide (Mal) complexes of Zn2+ were synthesized using different precursors and isolated in the solid state. These were found to be anionic with a Zn-to-saccharide ratio of 1:1 and 2:1 for monosaccharide and disaccharide complexes, respectively. Electrochemical behaviour in aqueous solution was studied by extensive cyclic voltammetric studies in the pH range 3.7-10.3. The effect of subcutaneously injected Zn-D-Fru, Zn-D-Gal and Zn-D-Glc complexes on the metallothionein synthesis in mice was found to be significant in the liver, but not in the brain.

Animals↗
PubMed1996

Transition metal saccharide chemistry and biology: synthesis, characterization, electrochemistry and EPR studies of oxovanadium (IV) complexes of saccharides and their derivatives and in vitro interaction of some of these with ribonuclease and deoxyribonuclease.

Low molecular weight, water-soluble saccharide complexes of oxovanadium(IV) have been synthesized and characterized by analytical, spectroscopic and electrochemical techniques. All the complexes were found to be mononuclear, possessing the VO2+ moiety. These are shown to be hydrolytically and oxidatively stable over a wide range of pH (1-12) and have been extensively characterized by absorption and EPR spectroscopy and by electrochemistry. Several correlations have been drawn from the data generated. Some of these complexes have been demonstrated to possess in vitro RNase inhibition activity with no effect on DNase. This suggests that these molecules closely mimic the substrate portion of the RNase-catalysed RNA hydrolysis and can act as transition-state analogues to RNase.

Deoxyribonucleases↗
PubMed1971

Ferritin-conjugated plant agglutinins as specific saccharide stains for electron microscopy: application to saccharides bound to cell membranes.

An electron microscopic stain for specific saccharides was prepared by the conjugation of ferritin to concanavalin A, a plant agglutinin that specifically binds to oligosaccharides containing terminal d-glucose, d-mannose, or sterically related sugar residues. A technique was developed to allow topological visualization of erythrocyte and other membranes by means of transmission electron microscopy, and the distribution of the binding sites for ferritin-concanavalin A on such membrane preparations was determined. The conjugate was found to bind specifically to the outer, but not the inner, surface of erythrocyte membranes. The number of conjugate molecules bound per unit area of the membrane was larger for rabbit than for human erythrocytes.

Animals↗
PubMed2000

Interaction of saccharides with rare earth metal ions: synthesis and characterisation of Pr(III)- and Nd(III)-saccharide complexes.

A number of complexes are synthesised with Pr(III) and Nd(III) employing the mono- and disaccharides, D-glucose, D-galactose, D-mannose, D-arabinose, D-ribose, D-xylose, maltose and lactose. The complexes are characterised by various spectral and analytical techniques, and based on these data, appropriate structures were assigned for all complexes.

Carbohydrates↗
PubMed1997

Transition-metal saccharide chemistry and biology: saccharide complexes of Cu(II) and their effect on in vivo metallothionein synthesis in mice.

Monosaccharide (D-Glc, D-Fru, D-Gal, D-Xyl, D-Rib) and disaccharide (Mal) complexes of Cu(II) were synthesized from two different precursors, viz. [NEt4]2 [CuCl2Br2] and CuCl2.2H2O, in nonaqueous media, and isolated in the solid state. The complexes were found to be primarily dimeric and trimeric and water soluble. These were characterized by diffuse reflectance, aqueous solution absorption, CD, FTIR, magnetic susceptibility, EPR, EXAFS, XANES, and elemental analysis. Aqueous solution stability in the pH range 4-8 was studied by cyclic voltammetry and absorption spectroscopy. The effect of subcutaneously injected Cu-Fru, Cu-Xyl, and Cu-Rib complexes on the in vivo metallothionein synthesis in mice was found to be significant in liver, but not in brain, in accordance with the observed copper accumulation in these tissues.

Animals↗
PubMed1985

Ricin D-saccharide interaction as studied by ultraviolet difference spectroscopy.

The interaction of ricin D with specific saccharides was investigated by ultraviolet difference spectroscopy. Upon binding to saccharides, ricin D displayed ultraviolet difference spectra with maxima at 280 nm and 288 nm. Such difference spectra suggest that the environment of a tyrosine residue(s) located at or near the saccharide-binding site is changed by the binding of saccharide. In addition to the two positive peaks, a small trough was observed around 300 nm in the complexes with galactose-containing saccharides but not in the complex with N-acetylgalactosamine or galactosamine, suggesting the participation of tryptophan in the binding with galactose-containing saccharides. The magnitude of the difference maxima increased with increasing concentration of saccharides until the binding site was saturated. From the variation of the maximum at 288 nm as a function of saccharide concentration, the association constants were obtained for the binding of saccharides to ricin D at various temperatures and pH's. The saccharide binding of ricin D decreased with increasing temperature and with decreasing pH below pH 6.0. It was suggested that difference maximum at 288 nm observed in the ricin D-saccharide interaction reflects the binding of saccharides to the high-affinity saccharide-binding site of ricin D.

Binding Sites↗
PubMed1994

Refined structure of concanavalin A complexed with methyl alpha-D-mannopyranoside at 2.0 A resolution and comparison with the saccharide-free structure.

The three-dimensional structure of the complex between methyl alpha-D-mannopyranoside and concanavalin A has been refined at 2.0 A resolution. Diffraction data were recorded from a single crystal (space group P2(1)2(1)2(1), a = 123.7, b = 128.6, c = 67.2 A) using synchrotron radiation at a wavelength of 1.488 A. The final model has good geometry and an R factor of 19.9% for 58 871 reflections (82% complete), within the resolution limits of 8 to 2 A, with F > 1.0sigma(F). The asymmetric unit contains four protein subunits arranged as a dimer of dimers with approximate 222 point symmetry. Each monomer binds one saccharide molecule. Each sugar is bound to the protein by hydrogen bonds and van der Waals contacts. Although the four subunits are not crystallographically equivalent, the protein-saccharide interactions are nearly identical in each of the four binding sites. The differences that do occur between the four sites are in the structure of the water network which surrounds each saccharide; these networks are involved in crystal packing. The structure of the complex is compared with a refined saccharide-free concanavalin A structure. The saccharide-free structure is composed of crystallographically identical subunits, again assembled as a dimer of dimers, but with exact 222 symmetry. In the saccharide complex the tetramer association is different in that the monomers tend to separate resulting in fewer intersubunit interactions. The average temperature factor of the mannoside complex is considerably higher than that of the saccharide-free protein. The binding site in the saccharide-free structure is occupied by three ordered water molecules and the side chain of Asp71 from a neighbouring molecule in the crystal. These occupy positions similar to those of the four saccharide hydroxyls which are hydrogen bonded to the site. Superposition of the saccharide-binding site from each structure shows that the major changes on binding involve expulsion of these ordered solvents and the reorientation of the side chain of Tyrl00. Overall the surface accessibility of the saccharide decreases from 370 to 100 A(2) when it binds to the protein. This work builds upon the earlier studies of Derewenda et al. [Derewenda, Yariv, Helliwell, Kalb (Gilboa), Dodson, Papiz, Wan & Campbell (1989). EMBO J. 8, 2198-2193] at 2.9 A resolution, which was the first detailed study of lectin-saccharide interactions.

Journal Article↗
PubMed2004

Various nondigestible saccharides open a paracellular calcium transport pathway with the induction of intracellular calcium signaling in human intestinal Caco-2 cells.

Ingestion of soluble nondigestible saccharides increases calcium absorption, and it is suggested that paracellular calcium transport contributes to this effect. However, cellular mechanisms and the contribution of active transport have not been clarified. This study examined the effects of 4 nondigestible saccharides, difructose anhydride (DFA) III, DFAIV, fructooligosaccharides, and raffinose, on active and passive calcium transport, permeability of paracellular pathways, and intracellular calcium signaling in a human intestinal Caco-2 cell monolayer. Net, active, and passive calcium transport were evaluated using (45)Ca. Transepithelial electrical resistance (TEER) and transport of lucifer yellow were measured as indicators of paracellular passage in differentiated Caco-2 cell monolayers incubated with 0-100 mmol/L of the various saccharides. The changes in intracellular calcium ion concentrations ([Ca(2+)](i)) were measured by fura-2 loading before and after the addition of each saccharide (50 or 100 mmol/L). The addition of 100 mmol/L of each saccharide to the apical medium of the Caco-2 cells enhanced net calcium transport without any changes in active calcium transport. Relative TEER was dose dependently and reversibly decreased by the addition of saccharides, and the decreases in TEER were highly correlated with net calcium transport (P < 0.001). Basolateral application of the saccharides had a slight or no effect on indicators of the paracellular pathway. Each saccharide caused an immediate and dose-dependent rise in [Ca(2+)](i) in the cells. The 4 nondigestible saccharides increased net calcium transport in the cells via the paracellular route through tight junctions. The rise in [Ca(2+)](i) induced by these saccharides may be involved in the opening of tight junctions.

Biological Transport↗