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At least 1,405 records · Page 78Linked to original sources
PubMed1994

Fast atom bombardment mass spectrometry of N-acetylated neoglycolipids of the 1-deoxy-1-phosphatidylethanolamino-lactitol-type.

N-Acetylated neoglycolipids (neoGL) of the 1-deoxy-1-phosphatidylethanolamino-lactitol-type (Lac-PtdEtn) carrying lactose, sialyllactose, disialyllactose, II3sialylgangliotetraose, II3,IV3disialylgangliotetraose, lacto-N-tetraose, IV6sialyllacto-N-tetraose, lacto-N-triaose, and bloodgroup A determinant as carbohydrate moieties were synthesized either chemically or enzymatically by glycosylation or deglycosylation of the parent compounds. The neoGL were then analyzed by fast atom bombardment mass spectrometry (FAB MS) with positive (FAB(+)) and negative ion (FAB(-)) detection. The resulting spectra showed intense pseudomolecular ions and characteristic fragmentations. FAB(-) spectra of the N-acetylated Lac-PtdEtn-type neoGL showed pseudomolecular ions (M-H)- of one magnitude higher intensity compared to those from the corresponding non-acetylated compounds. The main fragment ions were obtained from successive cleavage of the sugar units, thereby indicating the monosaccharide sequence. In FAB(+) spectra of the title compounds clearly detectable pseudomolecular ions were observed. The most prominent peaks, however, were obtained from cleavage of phosphatidic acid. The N-acetyl-ethyleneamine moieties of the corresponding glycosyl-Etn-fragments most probably formed five membered rings and thereby mesomery-stabilized cations. Secondary ions resulting from loss of the respective terminal sugars demonstrated the monosaccharide sequence.

Acetylation↗
PubMed1990

Is glucose the sole source of tissue browning in diabetes mellitus?

Reactions between glucose and protein are held to be responsible for the protein 'browning' reactions which occur in diabetes mellitus. In vitro, however, the formation of such novel protein fluorophores is dependent upon the metal-catalysed oxidation of the monosaccharide (glucose 'autoxidation'). Since other small oxidisable molecules are capable of 'browning' proteins via similar metal-catalysed oxidative mechanisms we suggest that protein modification in diabetes may not be restricted to reactions with monosaccharides but may also include other small autoxidisable molecules.

Arachidonic Acid↗
PubMed1992

Specific binding of phenolic glycolipid antigens from Mycobacterium bovis BCG with antibodies.

We studied the molecular binding specificity of two rabbit polyclonal sera generated against phenolic glycolipid antigens namely PheG1 B and PheG1 B-3 from Mycobacterium bovis BCG. PheG1 B is the well-known mycoside B (2-O-Me-alpha-L-Rhap 1----aglycone), while PheG1 B-3 is a recently found glycolipid (alpha-L-Rhap-(1----3)-2-O-Me-alpha-L-Rhap 1----aglycone). The interaction specificity was mainly explained in terms of the cavity volume of the antibodies paratope. The anti-PheG1 B antibodies paratope fits the 2-O-Me-alpha-L-Rhap ligand, while that of anti-PheG1 B-3 binds the disaccharide moiety of PheG1 B-3, and, with a higher affinity, the monosaccharidic unit localized at the non-reducing end. The B-3 antigen affinity is higher than that of antigen B for their homologous antibodies. This can be explained by the fact that the antibodies against phenolic glycolipid B-3 bind optimally to two sequential glycosyl residues suggesting the presence of two subsites. The immunoglobulin subsite with the major affinity binds the monosaccharidic unit localized at the non-reducing end.

Animals↗
PubMed1996

Development of protamine-bonded phase for separation of saccharides in liquid chromatography.

A protamine-bonded polymer gel was synthesized by passing this protein through an activated carbamate polyamine polymer gel layer. This new packing material was suitable for versatile separation of monosaccharides, oligosaccharides, sugar alcohols and uronic acids in liquid chromatography. The column packed with this gel could be operated at room temperature and gave excellent recovery for the reducing monosaccharides such as 2-deoxyribose, 2-deoxyglucose, ribose and mannose for which the conventional alkylamine-bonded phase column gave poor recovery. This column was used for the analysis of saccharides in urine using a post-column reaction detection system.

Amino Acid Sequence↗
PubMed1988

Influence of saccharides and sodium chloride on growth and differentiation of Trypanosoma cruzi.

The influence of saccharides, especially glucose and fructose, on the metacyclogenesis and growth of Trypanosoma cruzi has been investigated. In the absence of glucose and fructose in the media, both the percentage of metacyclic forms and the growth increased significantly. Furthermore, the addition of NaCl to the medium without monosaccharides strongly increased the formation of metacyclic forms. Presence of NaCl and absence of monosaccharides showed a synergic effect on differentiation of T. cruzi.

Animals↗
PubMed1986

Study of the endogenous lectins of the human platelet plasma membrane.

Plasma membranes isolated from human blood platelets and human intact platelets, either fresh or previously fixed, were investigated for their possible content in intrinsic sugar-binding proteins (lectins) which can specifically bind monosaccharides such as fucose, mannose, and galactose. Light and heavy fractions of platelet plasma membrane and intact platelets fixed with 2% formaldehyde and suspended in Tyrode's buffer pH 7.0 were incubated with either L-(1-3H)-fucose, D-(1-3H)-mannose or D-(1-3H)-galactose. Intact fresh platelets were incubated either with L-(1-3H)-fucose, D-(1-3H)-mannose, D-(1-3H)-galactose, D-(1-3H)-glucose and N-acetyl-D-(1-3H)-glucosamine or with the same monosaccharides radiolabeled with (14C). Samples of radiolabeled plasma membranes and intact platelets were electrophoresed on polyacrylamide gels, and prepared for spectrometry. Results indicate that isolated human platelet plasma membranes contain sugar-binding proteins, especially for L-fucose, for which the binding values in the light fraction are about 4 times greater than for D-galactose. For the heavy fraction, the binding value for L-fucose is about 12 and 89 times higher than for D-mannose and D-galactose, respectively. Similar to plasma membrane fractions, fixed intact human platelets bind predominantly L-fucose, followed in decreasing binding values by D-mannose and D-galactose. Unlike these, fresh human platelets bind mainly D-galactose, followed in affinity values by D-glucose, L-fucose and D-mannose and to a lesser extent by N-acetyl-D-glucosamine. The binding of radiolabeled sugars to isolated platelet plasma membranes and to the previously fixed intact platelets suggests that, an endogenous lectin-like activity is expressed by the platelet membrane.

Acetylglucosamine↗
PubMed1975

Cross-reactive antigens and immunity to diseases caused by encapsulated bacteria.

Antigenic structures may be shared among naturally occurring polymers, including proteins and polysaccharides. Proteins are polymers of amino acids. Cross-reactions between proteins are due to similarities in their overall shape rather than their individual amino acid components. Cross-reactions have been demonstrated among proteins with similar evolutionary development and structure, such as serum albumins or immunoglobulins. Polysaccharides are polymers of monosaccharides. In contrast to proteins, antigenic specificities may be conferred by mono-, di-, and trisaccharides. Since there are about 150 known naturally occurring monosaccharides, it is not unexpected that cross-reactions are demonstrable between polysaccharides from widely divergent sources.

Adult↗
PubMed1984

Immunochemical studies on the binding properties of Brucella abortus lipopolysaccharides to bovine precipitating antibodies.

The binding properties of Brucella abortus smooth lipopolysaccharides (LPS) to the precipitating antibodies in the serum of a B. abortus S2308 infected cow were studied by quantitative precipitin and precipitin-inhibition assays. Crude B. abortus lipopolysaccharides (cLPS) and chemical modification products of strains 1119.3, 19 and 2308 (virulent) were used for this study. In the quantitative precipitin assay, 13 micrograms of cLPS precipitated about 4.0-5.2 micrograms nitrogen of precipitating antibodies in 10 microliter of serum. After alkaline treatment (0.125 N NaOH at 56 degrees C for 1 hr), the alkali-treated lipopolysaccharides (aLPS) from S19 and S1119.3 maintained the maximum precipitability, but the precipitation profile was changed from a sigmoidal to a bell-shaped curve, and aLPS from S2308 was reduced to about 40% of its reactivity. These results indicate that some of the antigenic determinants blocked by other molecules were reshielded by alkaline treatment, and possibly that structural differences exist between virulent (S2308) and nonvirulent (S19 and S1119.3) strains. Among the monosaccharides and glycosides tested for inhibition of precipitation, methyl alpha-D-mannose was most active and about 3.3 times as active as D-mannopyranose (DMan) and only 1/200 as active as acid hapten or the carbohydrate moiety of cLPS prepared from S1119.3 (expressed as a monosaccharide of mol. wt 200) implying that the carbohydrate determinants of this antigen are probably related to a DMan alpha 1----linked compound. The precipitability of the antibodies in this serum was greatly reduced after absorption with cLPS and the precipitin reaction was completely inhibited by the carbohydrate moiety of LPS (O-antigen) S1119.3 demonstrating that the common antigenic determinants (hapten) of B. abortus LPS reacting with these precipitating antibodies are in the region of the carbohydrate moiety of the LPS.

Animals↗
PubMed1984

The application of the Milner-Avigad method for the quantitative determination of endouronidase activities.

The Milner-Avigad method (Milner, Y. and Avigad, G. (1967) Carbohydr. Res. 4, 359-361) has been shown to have high specificity for measuring the reducing powers of free hexuronic acids; its applicability in the quantitative determination of endouronidase activity was the purpose of this investigation. Among the constituent monosaccharides of glycosaminoglycans, hexuronic acids showed high color yield by this method, while xylose, galactose and N-acetylhexosamine recorded negligible color yield. Among the monosaccharide residues at the reducing terminals of oligosaccharides, only hexuronic acids exhibited color yield. However, the color yield was less than that of free hexuronic acids. Gel filtration chromatography of reaction products revealed that the cleavage of the oligosaccharide chains and the resultant exposure of new reducing terminals were not caused by the reaction procedures involved in this method. These data indicate that the Milner-Avigad method is useful for determining the presence of hexuronic acid residues preferentially at reducing terminals of glycosaminoglycan moieties. Thus, it supported the conclusion that the Milner-Avigad method is applicable for the quantitative determination of endouronidase activity using glycosaminoglycan as a substrate.

Animals↗
PubMed1978

Carbohydrate composition of cells and plasma membranes of Dictyostelium discoideum at selected stages of development.

Cells of Distyostelium discoideum representing four developmental stages were auto-analysed for constituent monosaccharides and their compositions compared. Rhamnose, ribose, fucose, glucose, mannose, galactose, glucosamine, galactosamine and an unidentified sugar were recovered after hydrolysis in 2 M HCl for 2 h at 100 degrees C. The relative proportions of the individual sugars were found to vary as a function of development. The largest variations were in the proportions contributed by galactose (from 2% of vegetative cell carbohydrate to 12% of the carbohydrate of fruiting bodies) and galactosamine (present in measurable quantity only in fruiting bodies). Plasma membrane "ghosts" were found to have the same monosaccharide constituents as whole cells, but in different proportions. Mannose contributed over 24% of the total carbohydrate recovered from aggregating cell "ghosts", but only 13% of carbohydrate recovered from "ghosts" prepared from vegetative cells. Galactose was the most abundant sugar recovered from vegetative "ghosts", and was second only to mannose in aggregating "ghosts".

Amino Sugars↗
PubMed1981

Uptake and distribution of placental glucocerebrosidase in rat hepatic cells and effects of sequential deglycosylation.

The clearance of native human placental glucocerebrosidase by rat liver shows the presence of two distinct enzyme forms with different recognition characteristics. The clearance and uptake of native enzyme by liver cells was compared to that of glucocerebrosidase sequentially treated with neuraminidase, beta-galactosidase and beta-N-acetylglucosaminidase. The initial rate of clearance of infused enzyme was increased greater than 10-fold for the asialo-, agalacto- and ahexoenzymes over that of native glucocerebrosidase. Incorporation of asialo enzyme was increased in hepatocytes over that of native enzyme, while the distribution of agalacto- and ahexoenzyme preparations was increased in non-parenchymal cells. This observation is consistent with the identification of a galactose receptor on hepatocytes and N-acetylglucosamine/mannose receptors on Kupffer cells. These data and inhibition studies by specified monosaccharide-terminal glycoprotein derivatives demonstrate the importance of these sugars in the uptake of this lysosomal enzyme by receptor-mediated endocytosis. Modification of the enzyme to expose certain monosaccharide moieties results in increased delivery to specific cell types. Therefore, naturally occurring receptors can be utilized for targeting glucocerebrosidase to the non-parenchymal cell in liver.

Acetylglucosaminidase↗
PubMed1985

Cartilage keratan sulphate: changes in chain length with ageing.

Keratan sulphate from sheep nasal cartilage of five different ages was isolated by a combination of methods. The mean length of the chains progressively increased with ageing, as assessed by the molar ratio of glucosamine to galactosamine or galactosaminitol. The mean length ranges from eight monosaccharides for the younger to seventeen monosaccharides for the older animals. The results suggest that the increase in keratan sulphate content of cartilage may be due to the increase in the length and not in the number of chains.

Aging↗
PubMed1989

Analysis of cancer-associated colonic mucin by ion-exchange chromatography: evidence for a mucin species of lower molecular charge and weight in cancer.

Cancer-associated mucins in the colon are antigenically distinct and glycosylated differently from their normal counterparts. Mucin-rich glycoconjugate preparations were made from nine non-neoplastic colons, seven colon cancers, and two different xenografts from mucin-producing human colon cancer cell lines, and radiolabeled with 3H. The preparation was applied to a DEAE-cellulose ion-exchange column, and eluted with a discontinuous ascending NaCl gradient resulting in seven discrete fractions or 'species'. Over half of the 3H-labeled glycoconjugates from specimens of non-neoplastic colonic epithelium eluted in fraction V (eluted with 0.25 NaCl). Significantly less of the 3H-labeled glycoconjugates from specimens of colon cancer eluted in fraction V (34%, P less than 0.0005), and there were significant increases in glycoconjugates eluted in fractions IV (P less than 0.008), III (P less than 0.0005), and II (P less than 0.028). Additional samples were prepared without the radiolabeling procedures, chromatographed on a DEAE-cellulose ion-exchange column, and analyzed for monosaccharide content. Each of the fractions contained the monosaccharides expected in mucin-type glycoproteins, but only sialic acid was differentially expressed in the seven fractions or 'species', occurring principally in the more charged species. However, differences in sialic acid content were not sufficient to explain the differences in retention on the ion-exchange column, nor were differences in O-acetylation of the mucins. Mucin-type glycoconjugates from colon cancers are relatively less charged than those from the normal colon, and elute at lower ionic strengths. Of interest, cancer-associated mucins appear to be of lower molecular weight than their normal counterparts. Additional studies of oligosaccharide and apomucin structure will be required to explain the molecular basis of these differences in charge.

Adenocarcinoma↗
PubMed1996

Acetylcholinesterase-induced respiratory burst in macrophages: evidence for the involvement of the macrophage mannose-fucose receptor.

It has long been suggested that acetylcholinesterase is capable of functioning in a non-cholinergic manner. However, very little is known about the molecular structures which mediate the interaction between this protein and the cellular membrane. Previously it was demonstrated that acetylcholinesterase interacted in a carbohydrate-specific manner with peritoneal macrophages and induced the 'respiratory burst' [1]. This study aimed to establish whether a carbohydrate-binding site exists on the acetylcholinesterase molecule itself, or alternatively, whether the macrophage carbohydrate-binding receptor is involved. No carbohydrate binding properties intrinsic to acetylcholinesterase were detected using affinity chromatography with immobilised monosaccharides, erythrocyte agglutination and gel-diffusion techniques. The interaction between acetylcholinesterase and several monosaccharide columns observed in this study appeared to be due to ionic interactions. Moreover, it was shown that a specific inhibitor of the enzymatic activity of AChE, BW284C51, could inhibit the peritoneal cell response not only to acetylcholinesterase, but also to several other stimuli, thus exhibiting a non-specific effect on macrophages. However, the inhibitory effects of specific ligands of the macrophage mannose-fucose receptor and the inability of non-glycosylated acetylcholinesterase to interact with macrophages suggested that the effect of acetylcholinesterase on peritoneal cells is most probably mediated by the macrophage mannose-fucose receptor. The role of the mannose-fucose receptor in triggering the respiratory burst response was supported by the fact that several ligands of these receptors were capable of inducing the functional response of macrophages.

Acetylcholinesterase↗
PubMed1990

Immunochemical studies of oligosaccharides obtained from the lipopolysaccharide of Brucella ovis.

Brucella ovis rough lipopolysaccharide (R-LPS) was studied with respect to its heterogeneity, chain length, sugar composition and immunological activity. R-LPS was mildly hydrolysed and oligosaccharides were recovered in the upper phase after partition with chloroform-methanol. Gel-filtration of the upper phase in a column of Bio-Gel P-2 yielded oligosaccharides of 2, 4, 6 and 7 monosaccharide units, 2-keto-deoxy-octulosonic acid (KDO), and monosaccharides. Strong acid hydrolysis followed by paper chromatography showed that the hexa- and heptasaccharides are both composed of glucose, KDO and an unidentified sugar while tetrasaccharide is composed of glucose, mannose and glucosamine. These three oligosaccharides were able to inhibit the LPS-antibody reaction in a solid phase radioimmunoassay, suggesting the oligosaccharides bear antigenic determinants of LPS.

Animals↗
PubMedDate not supplied

Purified native haptens of Brucella abortus B19 and B. melitensis 16M reveal the lipopolysaccharide origin of the antigens.

Purification of the Brucella polysaccharide referred to as native hapten (NH) and extracted from cells by the autoclaving procedure, was accomplished by ultrafiltration, followed by repetitive gel filtration using high-performance liquid chromatography on a "TSK-G2000-SW" column. The purified NH was analysed by SDS-PAGE, gas-liquid chromatography mass spectroscopy, and 13C and 1H NMR spectroscopy. NH from B. abortus B19 (NH-A) was shown to have a structure identical to that of A polysaccharide from B. abortus 1119-3, a linear homopolymer of alpha-1,2-linked-4,6-dideoxy-4-formamido-D-mannopyrannosyl residues. The structure of the NH from B. melitensis 16M (NH-M) was identified as a linear homopolysaccharide of the same sugar but composed of a pentasaccharide repeating unit in which four alpha 1,2-linked-4,6-dideoxy-4-formamido-D-mannopyrannosyl residues are linked alpha-1,3 to the last monosaccharide of the sequence. This structure is similar to that determined for the Brucella M polysaccharide from B. melitensis 16M. The discovery in highly purified NH preparations of covalently bound monosaccharides characteristic of lipopolysaccharide inner core regions e.g., quinovosamine, mannose and 3-deoxy-D-manno-octulosonate (KDO), indicates that this polysaccharide is derived from lipopolysaccharides (LPS) by hydrolytic conditions fortuitously generated during the extraction protocol. The antigenically important polysaccharides of Brucella are now established to be either A or M antigens. Polysaccharide B is a cyclic glucan with no structural or serological relationship to A or M polysaccharides, its apparent activity in diagnostic tests of infected cattle results from O polysaccharide contamination. This artefact, previously referred to as NH, results from LPS hydrolysis under the extraction conditions used to prepare polysaccharide B.

Antigens, Bacterial↗
PubMed2004

Fractionation of wheat straw by atmospheric acetic acid process.

Fractionation of wheat straw was investigated using an atmospheric acetic acid process. Under the typical conditions of 90% (v/v) aqueous AcOH, 4% H(2)SO(4) (w/w, on straw), ratio of liquor to straw (L/S) 10 (v/w), pulping temperature 105 degrees C, and pulping time 3h, wheat straw was fractionated to pulp (cellulose), lignin and monosaccharides mainly from hemicellulose with yields of approximately 50%, 15% and 35%, respectively. Acetic acid pulp from the straw had an acceptable strength for paper and could be bleached to a high brightness over 85% with a short bleaching sequence. Acetic acid pulp was also a potential feedstock for fuels and chemicals. The acetic acid process separated pentose and hexose in wheat straw to a large extent. Most of the pentose (xylan) was dissolved, whereas the hexose (glucan) remained in the pulp. Approximately 30% of carbohydrates in wheat straw were hydrolyzed to monosaccharides during acetic acid pulping, of which xylose accounted for 70% and glucose for 12%. The acetic acid lignin from wheat straw showed relatively lower molecular weight and fusibility, which made the lignin a promising raw material for many products, such as adhesive and molded products.

Acetic Acid↗