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PubMed2002

Transfer of high-mannose-type oligosaccharides to disaccharides by endo-beta-N-acetylglucosaminidase from Arthrobacter protophormiae.

Endo-beta-N-acetylglucosaminidase from Arthrobacter protophormiae (Endo-A) has transglycosylation activity, and high-mannose-type oligosaccharides are transferred to suitable glycosides as acceptor substrates. The acceptor specificity of Endo-A-catalyzed transglycosylation toward various disaccharides was investigated. To identify an effective acceptor for the transglycosylation by Endo-A, the reaction was carried out using various disaccharides. Endo-A transferred high-mannose-type oligosaccharides more efficiently to beta-linked disaccharides (cellobiose, gentiobiose, sophorose, and laminaribiose) than to alpha-linked disaccharides (isomaltose, maltose, nigerose, kojibiose, and trehalose) as acceptor substrates. The transglycosylation products, (Man)6GlcNAc-Glc-beta-Glc, were more rapidly hydrolyzed than (Man)6GlcNAc-Glc-alpha-Glc. These results indicate that Endo-A recognizes the anomeric configuration of the acceptor substrates, and beta-linked glycosides are suitable for the synthesis of transglycosylation products.

Journal Article↗
PubMed1998

Structural analysis of chromophore-labeled disaccharides and oligosaccharides by electrospray ionization mass spectrometry and high-performance liquid chromatography/electrospray ionization mass spectrometry.

Disaccharides and linear oligosaccharides were labeled with p-aminobenzoic ethyl ester (ABEE) chromophore and analyzed by negative ion electrospray ionization mass spectrometry (ESIMS). The formation of glycosylamines rather than reductive amination in the labeling reaction produced many characteristic fragment ions under in source collision-induced dissociation (CID). These ions provided unambiguous assignment of the position of the glycosidic linkages. This approach was extended to the analysis of linkages and the sequence of the linkages of several linear oligosaccharides. Additionally, the anomeric configuration of ABEE-labeled 1-3-, 1-4- and 1-6-linked glucose disaccharides could be differentiated according to the relative abundance of characteristic ions. Disaccharides with the same linkage but different monosaccharide compositions could be analyzed by on-line coupling of high-performance liquid chromatography with ESIMS.

Benzocaine↗
PubMed1999

Theoretical study of deprotonated glucopyranosyl disaccharide fragmentation.

Molecular orbital calculations were used to investigate the fragmentation of deprotonated glucopyranosyl disaccharides. Based on data from collisional activation and isotopic labeling experiments, fragmentation mechanisms are proposed, with calculated transition states being used to study the energetics of fragmentation. The calculations suggest that deprotonation at the C(2) hydroxyl of the non-reducing ring, following ring opening, may be important for disaccharide fragmentation. It is also shown that the stereochemistry at the 2-position of the non-reducing ring may have a significant effect on disaccharide fragmentation, particularly with regard to determination of the anomeric configuration.

Carbohydrate Conformation↗
PubMed2001

Microemulsion electrokinetic capillary chromatography of sulfated disaccharides derived from glycosaminoglycans.

Microemulsion electrokinetic capillary chromatography (MEEKC) is a capillary electrophoresis technique in which neutral and ionized species can be resolved according to their partitioning into moving oil droplets present in the operating buffer. In this report, we present for the first time the application of MEEKC in the analysis of glycosaminoglycans. An efficient method for the separation of the variously sulfated delta-disaccharides obtained following digestion of chondroitin and dermatan sulfates with chondro/ dermato lyases and derivatization with 2-aminoacridone is described. Nonsulfated, mono-, di-, and trisulfated delta-disaccharides were completely separated using the microemulsion octane/butan-1-ol/Sodium dodecyl sulfate (SDS) in 10 mM borate buffer, pH 9.3, at 25 kV. Agreement of the obtained disaccharide composition with literature values showed that MEEKC can be used for the analysis of glycosaminoglycans.

Animals↗
PubMed1992

Heavy metal binding to heparin disaccharides. I. Iduronic acid is the main binding site.

As model compounds for Ni(II)-binding heparin-like compounds isolated from human kidneys (Templeton, D.M. & Sarkar, B. (1985) Biochem. J. 230 35-42.), we investigated two disaccharides--4-O-(2-O-sulfo-alpha-L-idopyranosyluronic acid)-2,5-anhydro- D-mannitol, disodium salt (1a), and 4-O-(2-O-sulfo-alpha-L-idopyranosyluronic acid)-6-O- sulfo-2,5-anhydro-D-mannitol, trisodium salt (1b)--that were isolated from heparin after nitrous acid hydrolysis and reduction. The monosulfate (1a) was active whereas the disulfate (1b) was inactive in a high-performance liquid chromatography (HPLC) binding assay with the tracer ions 63Ni(II) 54Mn(II), 65Zn(II), and 109Cd(II). This result is in accord with the isolation of two 67Cu(II) and 63Ni(II) binding fractions from a complete pool of nitrous-acid-derived heparin disaccharides using sulfate gradients and a MonoQ anion exchange column on an FPLC system. One was identified as compound (1a) and the other as a tetrasulfated trisaccharide by high resolution FAB-MS, NMR and HPLC-PAD. Similarly, two synthetic disaccharides-methyl, 2-O-sulfo-4-O-(alpha-L-idopyranosyluronic acid)-2-deoxy-2-sulfamide-alpha-D-glucosamine, trisodium salt [IdopA2S(alpha 1,4)GlcNS alpha Me, 2a], and 2-O-sulfo-4-O-(alpha-L-idopyranosyluronic acid)-2-deoxy-2-sulfamide-6-O-sulfo- alpha-D-glucosamine, tetrasodium salt [IdopA2S (alpha 1,4)GlcNS6S alpha Me, 2b]--were shown to bind tracer amounts of 63Ni and 67Cu using chromatographic assays. Subsequently, 1H NMR titrations of 1a, 1b, 2a, and 2b with Zn (OAc)2 were analyzed to yield 1:1 Zn(II)-binding constants of 472 +/- 59, 698 +/- 120, 8,758 +/- 2,237 and 20,100 +/- 5,598 M-1, respectively. The values for 2a and 2b suggest chelation. It is suggested that the idopyranosiduronic acid residue is the major metal binding site. NMR evidence for this hypothesis comes from marked 1H and 13C chemical shift changes to the iduronic acid resonances after addition of diamagnetic Zn(II) ions.

Binding Sites↗
PubMed1992

Heavy metal binding to heparin disaccharides. II. First evidence for zinc chelation.

To map out the heavy metal binding sites of iduronic acid containing oligosaccharides isolated from human kidneys, we studied Zn(II) binding by nuclear magnetic resonance (NMR) and molecular modeling to two disaccharides isolated after nitrous acid depolymerization of heparin and two synthetic disaccharides representative of the heparin structure, namely, IdopA2S (alpha 1,4)AnManOH, 1 alpha, IdopA2S (alpha 1,4)AnManOH6S, 1b, IdopA2S-(alpha 1,4)GlcNS alpha Me, 2a, and IdopA2S (alpha 1,4)GlcNS6S alpha Me, 2b (see previous article in this series). A conformational analysis of the metal free and metal bound solutions was made by comparing calculated [(NOE)]s, [T1]s, and [J]s to experimental values. The 1C4, 4C1, and 2S0 conformations of the L-idopyranosiduronate ring and the 4E and 4T3 of the anhydro-D-mannitol ring are evaluated as are rotations about the C5-C6 hydroxymethylene of the AnManOH(6S) or GlcNS (6S) residues. The NOE between IdopA2S H1 and H3 and the known NOE between H2 and H5, as well as the T1 of IdopA2S H3, are introduced as NMR observables sensitive to the IdopA2S ring conformation. Similarly, a NOE between IdopA2S H5 and AnManOH(6S) or GlcNS(6S) H3 was observed that directly restricts the allowed interglycosidic conformational space. For all disaccharides, the Zn(II) bound spectral data are consistent with models in which these motions are partially "frozen" such that the 1C4 conformation of the IdopA2S is stabilized along with the 4T3 conformation of the AnManOH(6S) ring. The interglycosidic conformation is also stabilized in one of two minima. Electrostatic potential energy calculations gave the best overall agreement with experiment and suggest metal binding conformations with the carboxylate and ring oxygen of the IdopA2S residues (1C4 conformation) and either O3 of the GlcNS(6S) residues or the sulfate oxygens of the 6-sulphate for 2b providing additional chelating sites. These chelation models concur with the observation of marked 13C and 1H NMR chemical shifts for the IdopA2S resonances and of GlcNS H3 for 2 alpha and GlcNS6S C6 for 2b. This study of model compounds implicates the IdopA2S(alpha 1,4)GlcNS6S group as part of the heavy metal binding site in biologically important acidic oligosaccharides such as heparin.

Binding Sites↗
PubMed1997

Capillary electrophoresis of glycosaminoglycan-derived disaccharides: application to stability studies of glycosaminoglycan chitosan complexes.

Capillary zone electrophoresis (CZE) was used to separate the disaccharides produced by chondroitinase digestion of chondroitin sulfates. The main disaccharides formed upon depolymerization have identical charge and mass. Baseline resolution of these two compounds was achieved by selecting appropriate concentration and pH of a borate buffer. Validation of the method showed a good linearity of the response and a very satisfactory reproducibility of migration times with a relative standard deviation (RSD) of less than 0.4%. The reproducibility of peak areas was improved by using an internal standardization. The addition of cinnamic acid (internal standard) to the incubation medium allowed us to perform kinetic measurements of the depolymerization while keeping a baseline resolution of the two main disaccharides analyzed during the complete digestion course even when their concentration in the incubation medium increased. Application of this method to the comparison of the rate of hydrolysis of chondroitin sulfate and of a complex associating chondroitin sulfate with chitosan showed clearly that, at the physiological pH, chitosan protected the chondroitin sulfate from depolymerization. This phenomenon was more pronounced as the pH of the incubation medium was far from the optimum pH activity of the chondroitinase.

Chitin↗
PubMed2004

Determination of linkage position and anomeric configuration in Hex-Fuc disaccharides using electrospray ionization tandem mass spectrometry.

Fixed-energy sequential tandem mass spectrometry (MS(n)) capabilities offered by quadrupole ion trap instruments have been explored in a systematic study of six isomers of Gal-Fucalpha-OBenzyl disaccharides. Under collision-induced dissociation (CID), sodiated molecular species generated in the positive-ion electrospray ionization mode yield simple and predictable mass spectra. Information on interglycosidic linkages and configurations can be deduced from the relative intensities of the selected diagnostic fragments arising from the glycosidic bond cleavages and corroborated by the fragments arising from cross-ring cleavages. As the CID patterns are not dependent on the number of prior tandem mass spectrometric steps, structures can be unambiguously assigned by matching the spectra with a library. The rules governing the fragmentation behavior of this class of oligosaccharides were tested for a representative isomeric disaccharide, Glcbeta1,3Fucalpha-OAllyl. The findings establish a basis for using MS(n) with a quadrupole ion trap instrument to elucidate structures of hexose-fucose subunits from more complicated oligosaccharides. Energy-resolved mass spectra were also acquired by CID tandem triple-quadrupole mass spectrometry. The breakdown behavior of the molecular ions revealed patterns which could differentiate stereoisomers of Gal-Fuc disaccharides over a range of collision energy from 20 to 50 eV.

Disaccharides↗
PubMed2002

Enzyme-based sensor arrays for rapid characterization of complex disaccharide solutions.

An enzyme-based sensor array has been developed to detect multiple disaccharides in aqueous solutions. Porous agarose beads, derivatized with enzymes for assaying disaccharides, are localized within wells etched into a silicon chip in a regular 5 x 7 array. Each well is individually addressable and acts as a microanalysis chamber where sample solution passes through the agarose matrix and is exposed to the enzymes. Detection is achieved by observing the increase in absorbance of a quinoneimine dye produced during the reaction. This technique is used to quantify the disaccharides lactose, sucrose, and maltose and the monosaccharide glucose. Preexisting glucose in the sample complicates multicomponent sensing but can be accounted for by including a glucose sensor in the array. This detection strategy is applied to the simultaneous analysis of these sugars in several beverages.

Beverages↗
PubMed1995

Negative-ion fast atom bombardment tandem mass spectrometry for characterization of sulfated unsaturated disaccharides from heparin and heparan sulfate.

Negative-ion fast atom bombardment tandem mass spectrometry has been used in the characterization of non-, mono-, di- and trisulfated disaccharides from heparin and heparan sulfate. The positional isomers of the sulfate group of monosulfated disaccharides were distinguished from each other by negative-ion fast atom bombardment tandem mass spectra, which provide an easy way of identifying the positional isomers. This fast atom bombardment collision induced dissociation mass spectrometry/mass spectrometry technique was also applied successfully to the characterization of di- and trisulfated disaccharides.

Carbohydrate Sequence↗
PubMed1992

[Heat-induced decomposition of disaccharide Amadori compounds in quasi-water-free reaction conditions].

The thermally induced decomposition of disaccharide Amadori compounds has been compared to those of monosaccharide ones under almost water-free conditions. The structure of the synthesized maltulosyl compound has been proved to be 4C1-alpha-D-glucopyranosyl- (1----4)-2C5-beta-D-fructopyranosylglycine by 1H- and 13C-NMR spectroscopy. The decomposition of Amadori compounds has been used to study the kinetics of the browning reaction. Compared to fructosylglycine and maltotriulosylglycine, the browning of the disaccharide is faster. Curie point pyrolysis at 300 degrees C and investigation of the pyrolysate by gas chromatography/mass spectrometry have shown that the disaccharide component influences the thermal process. Furanes and furanones have been detected as predominant degradation products, the main one being 2(5H)-furanone. For the first time, we suggest a reaction pathway for the formation of these products via the Maillard reaction which includes 1,6-anhydroglucose.

Disaccharides↗
PubMed2002

Enhancement of paracellular transport of heparin disaccharide across Caco-2 cell monolayers.

The enhancement of paracellular transport of heparin disaccharide using several absorption enhancers across Caco-2 cell monolayers was tested. The cytotoxicity of these enhancers was also examined. The enhancing effects by Quillaja saponin, dipotassium glycyrrhizinate, 18beta-glycyrrhetinic acid, sodium caprate and taurine were determined by changes in transepithelial electrical resistance (TEER) and the amount of heparin disaccharide transported across Caco-2 cell monolayers. Among the absorption enhancers, 18beta-glycyrrhetinic acid and taurine decreased TEER and increased the permeability of heparin disaccharide in a dose-dependent and time-dependent manner with little or negligible cytotoxicity. Our results indicate that these absorption enhancers can widen the tight junction, which is a dominant paracellular absorption route of hydrophilic compounds. It is highly possible that these absorption enhancers can be applied as pharmaceutical excipients to improve the transport of macromolecules and hydrophilic drugs having difficulty in permeability across the intestinal epithelium.

Absorption↗
PubMed2006

Study of the dynamical properties of water in disaccharide solutions.

This work presents quasi-elastic neutron scattering (QENS) and neutron spin echo (NSE) findings on homologous disaccharide (i.e. trehalose, maltose and sucrose)/water solutions as a function of temperature. The dynamical properties of these systems are investigated by QENS, which, on the picosecond scale, allows for the characterisation of the diffusion of both solutes and solvent. On the other hand, NSE investigates the dynamics on the nanosecond scale, allowing for the relaxation times of the disaccharide/water systems to be evaluated. The experimental data highlight a strong slowing down of water in the presence of disaccharides. The whole set of findings indicates, therefore, a noticeable disaccharide-water interaction, which is more intense in the case of trehalose. This feature can justify its higher bioprotective effectiveness.

Disaccharides↗
PubMed1984

Determination of unsaturated glycosaminoglycan disaccharides by spectrophotometry on thin-layer chromatographic plates.

Chondroitin sulfate isomers and hyaluronate, digested with chondroitinase AC II and separated as unsaturated disaccharides by thin-layer chromatography on cellulose, were quantitated with scanning spectrophotometry using reflectance measurement at 232 nm. The sensitivity of the assay was increased by one order of magnitude as compared to previous modifications of the disaccharide analysis on cellulose. The method allowed quantitation of 0.2-20 micrograms of glycosaminoglycan uronic acid. Since the elution of the disaccharides from the plate could be omitted, the speed and reproducibility of the assay was enhanced.

Animals↗
PubMed1989

The disaccharide composition of heparins and heparan sulfates.

Heparin and heparan sulfate can be cleaved selectively at their N-sulfated glucosamine residues by direct treatment with nitrous acid at pH 1.5. These polymers can also be cleaved selectively at their N-acetylated glucosamine residues by first N-deacetylating with hydrazine and then treating the products with nitrous acid at pH 4. These procedures have been combined and optimized for the conversion of these glycosaminoglycan chains into their disaccharide units. A modified hydrazinolysis procedure in which the glycosaminoglycans were heated with hydrazine:water (70:30) containing 1% hydrazine sulfate gave rapid rates of N-deacetylation and minimal conversion of the uronic acid residues to their hydrazide derivatives. Under these conditions, N-deacetylation was complete in 4 h and the beta-eliminative cleavage of the polymer chains that occurs during hydrazinolysis (P. N. Shaklee and H. E. Conrad (1984) Biochem. J. 217, 187-197) was eliminated. Treatment of the N-deacetylated polymer with nitrous acid at pH 3 for 15 h at 25 degrees C then gave simultaneous cleavage at the N-unsubstituted glucosamine residues and the N-sulfated glucosamine residues. These deamination conditions minimized, but did not eliminate, the side reaction in which nitrous acid-reactive glucosamine residues undergo ring contraction without glucosaminide bond cleavage. Thus, the disaccharides were obtained in a yield of 90% of those originally present in the glycosaminoglycan chains. Since the ring contraction side reaction occurs randomly at the diazotized glucosamine residues, the disaccharides formed in the pH 3 nitrous acid reaction were recovered in proportions equal to those in the original glycosaminoglycan chain.(ABSTRACT TRUNCATED AT 250 WORDS)

Chromatography, Gel↗
PubMed1984

Disaccharide uptake by brush-border membrane vesicles lacking the corresponding hydrolases.

Intestinal disaccharide uptake was studied with isolated brush-border membrane vesicles lacking the corresponding hydrolase. Either 15-day-old chick intestine, lacking both trehalase and lactase, or newborn pig intestine, lacking sucrase, was used. Both animal species yielded osmotically active vesicles capable of D-glucose/Na+ cotransport with a positive overshoot test. Vesicles from either origin gave quantitatively similar results in regard to both initial uptake rates and relative vesicle volumes. The nontransported analogs D-mannitol and L-glucose were used as diffusion markers. When tested with the appropriate disaccharidase-lacking vesicles, lactose, trehalose and sucrose exhibited uptake rates indistinguishable from those of D-mannitol and L-glucose. These uptakes were unaffected by the presence or absence of Na+, phlorizin and Tris. Chromatographic analysis confirmed the lack of hydrolysis of each disaccharide after prolonged incubation. The inescapable conclusion seems to be that intact disaccharides are not transported through the brush-border membrane, their uptake occurring through simple diffusion.

Animals↗
PubMed1984

Synthesis of the disaccharide 6-O-beta-D-galactopyranosyl-2-acetamido-2-deoxy-D-galactose using immobilized beta-galactosidase.

The disaccharide 6-O-beta-D-galactopyranosyl-2-acetamido-2-deoxy-D-galactose has been synthesized by transfer of the beta-D-galactopyranosyl residue from lactose to 2-acetamido-2-deoxy-D-galactose utilizing the transferase activity of beta-galactosidase from E. coli. To make the enzyme reusable, it was applied in an immobilized form covalently bound to Sepharose CL-4B. The yield of the disaccharide was about 20%, calculated on the amount of acetamido-deoxy-D-galactose added. The disaccharide could also be obtained by reversal of the hydrolytic activity of the enzyme, using D-galactose and 2-acetamido-2-deoxy-D-galactose as substrate. The yield in this reaction, however, was only 2-3% under the conditions applied.

Chromatography, High Pressure Liquid↗
PubMed1991

A one-step C-linked disaccharide synthesis from carbohydrate allylsilanes and tri-O-acetyl-D-glucal.

The reaction of protected glucuronic esters 2 and 7, as well as D-glucuronolactone derivative 11, with (trimethylsilyl)methylmagnesium chloride in ether led to the corresponding stable bis-silyl adducts 3, 8, and 12, respectively. In Peterson-type reactions catalysed with mild acid, these compounds yielded carbohydrate allylsilanes 4, 9, and 13, respectively. Synthons 4 and 9 were coupled with tri-O-acetyl-D-glucal in a boron trifluoride-catalysed "carbon-Ferrier rearrangement" reaction to give C-linked disaccharides i.e., so-called "C-disaccharides" 16 and 17, respectively, in fair yields. Structural assignments of the anomeric configuration at the C-glycosylic carbon in the 2,3-unsaturated ring of these coupling products with the aid of n.m.r. spectroscopic methods unambiguously showed that alpha-D-C-linked disaccharides had been formed.

Calcium Gluconate↗