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At least 505 records · Page 28Linked to original sources
PubMed2003

Preparation and reactivity of a novel disaccharide, glucosyl 1,5-anhydro-D-fructose (1,5-anhydro-3-O-alpha-glucopyranosyl-D-fructose).

A novel disaccharide, glucosyl 1,5-anhydro-D-fructose (1,5-anhydro-3-O-alpha-glucopyranosyl-D-fructose, GAF) was enzymatically prepared from 1,5-anhydro-D-fructose (1,5-AF) and cyclomaltoheptaose (beta-cyclodextrin). Cyclodextrin glucanotransferase transferred various sizes of maltooligosaccharide to 1,5-AF. Glucoamylase digested the maltooligosyl chain of the products to a glucosyl residue giving a final product, GAF. An NMR analysis of GAF elucidated that the glucose residue was linked to C-3 of the 1,5-AF residue with an ether linkage. Reactivity on the aminocarbonyl reaction of GAF with bovine serum albumin was lower than that of 1,5-AF, but was higher than that of glucose.

Animals↗
PubMed1996

Synthesis of glycolipids containing disaccharides and two longer alkyl chains and their applications as enzyme modifiers.

The aminolysis between p-(aminomethyl)benzoic acid and lactobiono-1,5-lactone was carried out in Me2SO in quantitative yield. The amide formed thus was used directly for the final reaction without isolation of the intermediate from the reaction mixture. This simple one-pot procedure finished a convenient and useful synthesis of the target N-[p-(dialkyl-L-glutamatecarbonyl)-benzyl]lactobionamides. The phase-transition temperature of glycolipids was shown to greatly depend on the structure between the hydrophilic moiety and the hydrophobic segment of the glycolipids. The yield of proteins of lipases coated with the glycolipids containing disaccharides remarkably increased with alkyl-chain length, which was higher than that with glycolipids containing monosaccharides. The yields were also closely correlated to the origin of the lipases. The enzymatic reactivity of lipid-coated lipase PS was seldom affected by the hydrophobic segment of lipids, but its enantioselectivity was mainly affected by the hydrophilic moiety of lipids.

Amides↗
PubMed1997

Identification of an alpha-D-Manp-(1-->8)-Kdo disaccharide in the inner core region and the structure of the complete core region of the Legionella pneumophila serogroup 1 lipopolysaccharide.

A disaccharide alpha-D-mannopyranosyl-(1-->8)-3-deoxy-D-manno-octulosonic acid [alpha-D-Manp-(1-->8)-Kdo] was released by mild acid degradation of Legionella pneumophila serogroup 1 (strain Philadelphia 1) lipopolysaccharide (LPS) and identified using NMR spectroscopy and GLC-MS of derived products. These data, together with methylation analysis of the native LPS and previously reported data [Y.A. Knirel, H. Moll, and U. Zähringer, Carbohydr. Res., 293 (1996) 223-234], allowed elucidation of the complete core region of the LPS as having the following nonasaccharide structure: [Sequence: see text]

Carbohydrate Conformation↗
PubMed1997

Trisaccharide synthesis by glycosyl transfer from p-nitrophenyl beta-D-N-acetylgalactosaminide on to disaccharide acceptors catalysed by the beta-N-acetylhexosaminidase from Aspergillus oryzae.

The beta-N-acetylhexosaminidase from Aspergillus oryzae catalysed the transfer of beta-D-N-acetylgalactosaminyl residues from p-nitrophenyl beta-D-N-acetylglucosaminide on to disaccharide acceptors consisting of thioethyl glycosides of alpha-D-Glc-(1-->4)-beta-D-Glc, beta-D-Glc-(1-->4)-beta-D-Glc and beta-D-Glc-(1-->6)-beta-D-Glc. The principle of 'anomeric control' was exemplified by the results which showed that an alpha-linkage between the units of the acceptor favoured exclusively the formation of a new (1-->4)-linkage, whereas the beta-configuration in the acceptor led to a mixture of (1-->4)- and (1-->3)-linked products, as observed for simple glycosides of monosaccharide acceptors. With the thioethyl beta-lactoside as acceptor, beta-D-Gal-(1-->6)-beta-D-Gal-(1-->4)-beta-D-GlcSEt was formed, owing to the action of residual beta-D-galactosidase activity in the N-acetylhexosaminidase on the thioethyl beta-lactoside acting as both donor and acceptor.

Acetylgalactosamine↗
PubMed1998

Synthesis of a jojoba bean disaccharide.

A synthesis of the disaccharide recently isolated from jojoba beans, 2-O-alpha-D-galactopyranosyl-D-chiro-inositol, has been achieved. The suitably protected chiro-inositol unit was prepared by an enantiospecific synthesis from L-xylose utilizing SmI2-mediated pinacol coupling as a key step.

Carbohydrate Conformation↗
PubMed1999

Syntheses of methyl (4,6-dideoxy-alpha-L-lyxo-hexopyranosyl)-(1-->3)- and (4-deoxy-4-fluoro-alpha-L-rhamnopyranosyl)-(1-->3)- 2-acetamido-2-deoxy-alpha-D-glucopyranosides, analogs of the mycobacterial arabinogalactan linkage disaccharide.

We have made thioglycoside donors for the 4,6-dideoxy-L-lyxo-hexopyranosyl ('4-deoxy-L-rhamnosyl') and 4-deoxy-4-fluoro-L-rhamnosyl monosaccharide residues. The preparation of the deoxyfluororhamnose was not straightforward, and revealed some unexpected behavior of the diethylaminosulfur trifluoride (DAST) reagent. The new glycosyl donors were used to synthesize two analogs of the mycobacterial arabinogalactan linkage disaccharide -->4)-alpha-L-Rha-(1-->3)-alpha-D-GlcNAc. These analogs are prototypes for a family of potential inhibitors of the enzymes involved in the early stages of cell-wall construction in mycobacteria.

Carbohydrate Conformation↗
PubMed2000

Regioselective synthesis of p-nitrophenyl glycosides of beta-D-galactopyranosyl-disaccharides by transglycosylation with beta-D-galactosidases.

The beta-D-galactosidase from porcine liver induced regiospecific transglycosylation of beta-D-galactose from beta-D-Gal-OC6H4NO2-o to OH-6 of, respectively, p-nitrophenyl glycoside acceptors of Gal, GlcNAc and GalNAc to afford beta-Gal-(1-->6)-alpha-Gal-OC6H4NO2-p, beta-Gal-(1--> 6)-beta-Gal-OC6H4NO2-p, beta-Gal-(1-->6)-alpha-GalNAc-OC6H4NO2-p, beta-Gal-(1-->6)-beta-GalNAc-OC6H4NO2-p, beta-Gal-(1-->6)-alpha-GlcNAc-OC6H4NO2-p, and beta-Gal-(1-->6)-beta-GlcNAc-OC6H4NO2-p. The enzyme showed much higher transglycosylation activity for the alpha-glycoside acceptors than the corresponding beta-glycoside acceptors. The regioselectivity of the beta-D-galactosidase from Bacillus circulans ATCC 31382 greatly depended on the nature of the acceptor. When alpha-D-GalNAc-OC6H4NO2-p and alpha-D-GlcNAc-OC6H4NO2-p were used as acceptors, the enzyme showed high potency for regioselective synthesis of beta-Gal-(1-->3)-alpha-GalNAc-OC6H4NO2-p and beta-Gal-(1-->3)-alpha-GlcNAc-OC6H4NO2-p in high respective yields of 75.9 and 79.3% based on the acceptors added. However, replacement of beta-D-Gal-OC6H4NO2-p by beta-D-GalNAc-OC6H4NO2-p did change the direction of galactosylation. The enzyme formed regioselectively beta-Gal-(1-->6)-beta-Gal-OC6H4NO2-p with (beta-Gal-1-->(6-beta-Gal-1-->)n6-beta-Gal-OC6H4NO2-p, n = 1-4). No beta-(1-->3)-linked product was detected during the reaction. Use of the two readily available beta-D-galactosidases facilitates the preparation of (1-->3)- and (1-->6)-linked disaccharide glycosides of beta-D-Gal-GalNAc and beta-D-Gal-GlcNAc.

Animals↗
PubMed2000

Thermotropic and lyotropic properties of long chain alkyl glycopyranosides. Part II. Disaccharide headgroups.

We have investigated the thermotropic and lyotropic properties of some long chain alkyl glycosides with disaccharide headgroups. The thermotropism was measured with polarising microscopy and additionally the lyotropism with the contact preparation method, Fourier-transform Infrared (FTIR) spectroscopy, X-ray diffraction and small angle neutron scattering. A broad thermotropic as well as lyotropic polymorphism was found. The compounds displayed thermotropic S(A) (lamellar) and cubic phases, and the investigation of the lyotropic phase behaviour led to the observation of inverted bicontinuous cubic V(II) phases, lamellar L(alpha) phases, normal bicontinuous cubic V(I) phases, normal columnar H(I) phases, normal discontinuous cubic I(I) phases and lyotropic cholesteric phases. The phases are discussed with respect to the chemical structures that have been varied systematically to derive structure-property relationships.

Carbohydrate Conformation↗
PubMed1997

An analytical method for the quantitation of mannitol and disaccharides in serum: a potentially useful technique in measuring small intestinal permeability in vivo.

An electrochemical-HPLC method for the determination of mannitol and lactulose is presented which may facilitate routine testing of intestinal permeability by requiring only a single blood sample instead of a 6-hour urine collection. Chromatographic conditions are described which allow separation of the closely related sugars lactulose and the dietary disaccharides lactose and sucrose. Preliminary results in normal controls and patients with untreated coeliac disease are presented.

Adult↗
PubMed1978

Analysis of mono- and disaccharides by high-performance liquid chromatography of the benzyloxime-perbenzoyl derivatives.

A group of biologically important mono- and disaccharides are separated by high-performance liquid chromatography of the benzyloxime-perbenzoyl derivatives on a normal-phase microparticulate column with a hexane-dioxane mixture as the eluting solvent. A single, quantifiable derivative of each sugar is formed easily. These derivatives are detected by UV absorption at either 230 or 254 nm, with a sensitivity in the picomole range at the former wavelength. The sugars in the residues from the evaporation of small aliquots of biologic fluids (10-100 microliter) are derivatized without prior isolation and are determined quantitatively by the use of appropriate internal standards. The analyses could be performed routinely with a simple, inexpensive instrument.

Benzoates↗
PubMed1979

Determination of sulphated disaccharides from chondroitin sulphates by high-performance liquid chromatography.

A sensitive method for the determination of chondroitin 4- and 6-sulphate is presented. After chondroitinase digestion of the chondroitin sulphate preparations, the obtained disaccharides are separated on a weak anion-exchange resin in a high-performance liquid chromatography system. The method was used to study 4-sulphate to 6-sulphate ratios in chondroitin sulphates prepared from bovine nasal cartilage and human nucleus pulposus. The results show clearly that these two preparations contain considerable amounts of both isomers.

Animals↗
PubMed2003

Disaccharide analysis of glycosaminoglycans synthesized by cardiac myxoma cells in tumor tissues and in cell culture.

We analyzed the main disaccharide units of glycosaminoglycans synthesized by cardiac myxoma cells in vivo and in cell culture using high-performance liquid chromatography after 1-phenyl-3-methyl-5-pyrasolone labeling. Cardiac myxoma tissues contained large amounts of chondroitin-6-sulfate (46%) and hyaluronic acid (32%), along with some chondroitin-4-sulfate (13%), chondroitin (6%), and much less dermatan sulfate (3%). Cultured cardiac myxoma cells synthesized mainly chondroitin-6-sulfate. The abundant glycosaminoglycans in myxoma tissues may make up the characteristic friable gelatinous matrix which is favorable for embolism and tumor cell growth.

Adult↗
PubMed2002

3-Methylbutanoyl and 3-methylbut-2-enoyl disaccharides from green coffee beans (Coffea arabica).

Three 3-methylbutanoyl and 3-methylbut-2-enoyl disaccharides isolated from green coffee beans (Coffea arabica) were identified as 3-methylbutanoyl-1-O-beta-D-glucopyranosyl-beta-D-apiofuranoside, 3-methylbutanoyl-6-O-alpha-D-glucopyranosyl-beta-D-fructofuranoside, and 3-methylbut-2-enoyl-1-O-beta-D-glucopyranosyl-beta-D-apiofuranoside. The structures were established by one- and two-dimensional 1H and 13C NMR spectra as well as by ESI MS/MS spectra.

Acylation↗
PubMed2002

Influence of terminal residue on adjacent disaccharide immunogenicity.

Aberrant O-glycosylation of cell surface mucin antigens is characteristic of epithelial cancer cells. For example, Thomsen-Friedenreich disaccharide (TFD) is a chemically well-defined carbohydrate antigen with a documented link to malignancy. There have been many attempts to improve immune response to carbohydrate antigens, for use in immunotherapy. As part of an alternative strategy to improve carbohydrate immunogenicity, we studied the influence of terminal benzyl (Bzl) or p-nitrophenyl (pNP) residue on immunogenicity of adjacent TFD. Mice immunized with keyhole limpets hemocyanin-TFD (KLH-TFD), KLH-TFD(alpha)Bzl, or KLH-TFD(alpha)pNP produced anti-KLH antibodies, which were analyzed by enzyme-linked immunosorbent assay (ELISA). KLH-TFD did not give significant anti-TFD antibody titer, confirming the poor immunogenicity of TFD. Immunization with KLH-TFD(alpha)Bzl and KLH-TFD(alpha)pNP raised antibody titers against TFD(alpha)Bzl and TFD(alpha)pNP, respectively. KLH-TFD(alpha)Bzl also gave higher anti-TFD antibody response, whereas KLH-TFD(alpha)pNP did not, indicating that terminal Bzl residue improves immune response to adjacent carbohydrate. Analysis of anti-TFD(alpha)Bzl or anti-TFD(alpha)pNP IgG antibodies by competitive ELISA, using carbohydrate-related antigens as inhibitors, demonstrated their high specificity to their respective antigens. Anti-TFD(alpha)pNP antibody was not inhibited by TFD, but was significantly inhibited by GalNAc(alpha)pNP. The fact that p-nitrophenol (pNPol) has more competitive ability that GalNAc indicates that terminal polar residue is the main target antigen. In contrast, anti-TFD(alpha)Bzl antibody was inhibited to a similar degree by GalNAc(alpha)Bzl and TFD, confirming the carbohydrate recognition by antibodies yielded by terminal non-polar modification of the immunogen.

Animals↗
PubMed1985

Aorta collagen metabolism in spontaneously hypertensive and aortic-constricted rats: variations in enzyme activities concerned with disaccharide unit synthesis and degradation according to blood pressure and age.

Two enzyme activities concerned with collagen disaccharide unit metabolism (UDP-glucose: collagen glucosyltransferase and glucosyl-galactosyl-hydroxylysine glucohydrolase) have been studied in the thoracic aortic wall together with 4-prolyl hydroxylase activity and 4-hydroxyproline content in spontaneously hypertensive rats (SHR) at the prehypertensive, hypertensive and sustained hypertensive stages (respectively 32 days, 12 weeks and 19 weeks of age). They were compared with values observed in age-matched normotensive Wistar Kyoto rats (WKY). The same studies have been performed in parallel on aortic-constricted rats (ACR) 8 days after suprarenal constriction of the abdominal aorta. Negative regressions of all three specific activities as function of age were observed. The most striking difference observed between the SHR and the WKY was the increase of glucosyltransferase specific activity, already found at the prehypertensive stage and continuing thereafter; the glucohydrolase specific activity was increased only during the establishment of hypertension whereas no modification was found with prolyl hydroxylase at any stage. However, a diminution of hydroxyproline concentration was seen at all ages while total hydroxyproline mass remained unaffected. The alterations of the aortic collagen metabolism observed in the ACR recall those seen in the SHR at the prehypertensive stage: the only significant modification was that of glucosyltransferase activity. Correlation was found between glucosyltransferase activity and blood pressure level in the two animal models.

Age Factors↗
PubMed2001

A novel disaccharide substrate having 1,2-oxazoline moiety for detection of transglycosylating activity of endoglycosidases.

A disaccharide substrate of Manbeta1-4GlcNAc-oxazoline 2 was designed and synthesized as a novel probe for detection of the transglycosylating activity of endoglycosidases. A regio- and stereoselective transglycosylation reaction of 2 to GlcNAcbeta1-O-pNP or Dns-Asn(GlcNAc)-OH catalyzed by endo-beta-N-acetylglucosaminidase from Mucor hiemalis (Endo-M) and endo-beta-N-acetylglucosaminidase from Arthrobacter protophormiae (Endo-A) has been demonstrated for the first time, resulting in the core trisaccharide derivative Manbeta1-4GlcNAcbeta1-4GlcNAcbeta1-O-pNP 8 (or -(Dns)Asn-OH). Interestingly, the transglycosylation proceeds irreversibly; the resulting trisaccharide 8 was not hydrolyzed by Endo-M and Endo-A. Based on these results, a new mechanism including an oxazolinium ion intermediate has been proposed for the endoglycosidase-catalyzed hydrolysis or transglycosylation.

Carbohydrate Sequence↗