Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Glycoconjugates”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 559 records · Page 31Linked to original sources
PubMed1979

Ferrocyanide enhancement of concanavalin A-ferritin and cationized ferritin staining blood cell surface glycoconjugates.

Ferrocyanide was used to enhance cationized ferritin and concanavalin A-ferritin (Con A-ferritin) staining of surface glycoconjugates of peripheral blood and bone marrow cells from rabbits and humans. The glutaraldehyde-fixed cells were stained with Con A-ferritin or cationized ferritin and then exposed to a ferrocyanide solution. The resulting cuboidal and irregular stain deposits averaged 50 nm in diameter when viewed with the transmission (TEM) and scanning electron microscope (SEM). Rabbit blood cells demonstrated more Con A binding sites than human blood cells and the decrease in binding sites observed with maturation of human granulocytic and erythrocytic cells was not evident in rabbit cells. Differences in binding of cationized ferritin to rabbit and human cell surfaces were less prominent than that observed for Con A. These results extend previous studies of blood cell surface glycoconjugates and demonstrate that ferrocyanide enhancement significantly facilitates SEM evaluation of Con A-ferritin and cationized ferritin bound to cell surfaces.

Animals↗
PubMed1984

Light microscopic detection of sugar residues in glycoconjugates of salivary glands and the pancreas with lectin-horseradish peroxidase conjugates. II. Rat.

Salivary glands and pancreases from male rats were stained with a battery of ten different lectin-horseradish peroxidase conjugates. Qualitative and quantitative differences were observed in the content of terminal sugar residues in stored secretory glycoproteins in parenchymal cells of glands having a similar histological structure. Heterogeneity in the content of secretory glycoconjugates was also found between cells in the same exocrine glands, which were previously thought to be identical on the basis of classical morphological and histochemical staining studies. Similar differences were observed in the structure of glycoconjugates associated with the apical surface of epithelial cells lining glandular excretory ducts. Intercalated ducts presented a gland specific staining pattern different from that of the glandular secretory cell population, whereas striated duct and interlobular duct epithelial cells stained similarly in all major rat exocrine glands. A comparison of lectin binding patterns in identical histological sites in the mouse, reported in a companion paper, is provided, and the similarities and differences between these two rodent species are discussed. In addition to providing valuable information concerning the localization and structure of tissue complex carbohydrates, a comparison of staining in the same tissue sites with labelled lectins reported biochemically to have similar binding specificity has revealed interesting differences in the binding specificity of these macromolecules.

Animals↗
PubMed1981

Cytochemical localization of glycoconjugates in rat peritoneal mast cells during degranulation.

Cytochemical methods for the localization of glycoconjugates including concanavalin A-horseradish peroxidase (ConA-HRP) and dialysed iron were used to study the distribution of glycoconjugates in mast cell granules during degranulation. The ConA-HRP method revealed intense staining of discharged mast cell granules. Dialysed iron staining was seen at the granule periphery, with extruded granules exhibiting more intense staining than undischarged granules.

Animals↗
PubMed1993

Leishmania donovani surface glycoconjugate GP36 is the major immunogen component of the fucose-mannose ligand (FML).

Leishmania donovani promastigote glycoconjugate ligands, studied in our laboratory, that interact with the internalization receptors on BALB/c macrophages: the 'fucose mannose ligand' (FML), the 'phosphate mannogalactan ligand' (PMGL), and the 'lipopeptidephosphoglycan' (LPPD), interfered also with interaction between amastigotes and host cells in vitro. Among the three compounds studied, the FML was shown to be the most potent inhibitor of both promastigote and amastigote internalization, and to be present on parasite surface during the vertebrate-host cycle. The FML, but not the other two glycoconjugates, is a potent immunogen in rabbits (ELISA, agglutination and immuno-blots). Rabbit hyperimmune sera recognized essentially the 36 kDa band of FML. Mouse monoclonal antibodies against FML recognized either the 36 kDa or the 55 kDa band. No cross-reactivity between these two FML components was detected. No antigenic similarity could be detected between the 36 and 55 kDa bands of FML and the 'GP63' (promastigote surface proteinase) major surface leishmanial antigen. The 36 kDa-glycoprotein was identified as the major FML antigenic fraction and designated 'GP36'. The integrity of the glycidic moiety was necessary for its antigenicity. This L. donovani surface glycoprotein is apparently one of the major molecules involved in interactions between the parasite and the vertebrate host.

Animals↗
PubMed1985

Blot analyses of glycoconjugates: enzyme-hydrazide--a novel reagent for the detection of aldehydes.

A procedure for the general staining of glycoproteins and other glycoconjugates on protein blots has been developed. Aldehydes are formed on the sugars of glycoconjugates by periodate oxidation which then react with hydrazide groups of enzyme-hydrazides, a novel reagent designed for aldehyde detection. The bound enzyme-hydrazide is demonstrated histochemically. The new assay is advantageous over periodic-acid Schiff staining of gels as its reagents and signals are stable and the process is simple and expedient, and provides greater sensitivity.

Aldehydes↗
PubMed1988

Monosaccharide analysis of glycoconjugates by anion exchange chromatography with pulsed amperometric detection.

The method of anion exchange chromatography followed by pulsed amperometric detection (AE-PAD; Johnson, D. C., and Polta, T. Z. (1986) Chromatogr. Forum 1, 37-44) has been applied to the compositional analysis of glycoconjugates. Using 22 mM NaOH as a column effluent, underivatized fucose, galactosamine, glucosamine, galactose, glucose, and mannose were readily separated in 15 min at a flow rate of 1 ml/min. The limit of quantification of the monosaccharides was better than 100 pmol (signal to noise ratio 184:1). AE-PAD was employed to quantify the monosaccharides of several glycoproteins, glycopeptides, and oligosaccharides after hydrolysis with 2 M trifluoroacetic acid. Both neutral and amino sugars could be rapidly estimated in a single chromatographic step using AE-PAD. Complete release of N-acetylglucosamine required more vigorous hydrolysis conditions (Lee, Y. C. (1972) in Methods in Enzymology (Ginsburg, V., Ed.), Vol. 28, pp. 63-73, Academic Press, New York). In both glycopeptides and oligosaccharides, approximately one less residue of Man than predicted was determined. Both AE-PAD and liquid chromatographic analysis of borate-monosaccharide complexes with fluorometric detection (Mikami, H., and Ishida, Y. (1983) Bunseki Kagaku 32, E207-E210) gave similar quantification of mannose and other sugars. The capability of rapid, sensitive quantification of underivitized monosaccharides should facilitate structural analysis of glycoconjugates.

Amino Sugars↗
PubMed1984

Nonuniform loss of membrane glycoconjugates during in vivo aging of human erythrocytes: studies of normal and diabetic red cell saccharides.

Changes occurring in membrane saccharides during the in vivo aging of normal human erythrocytes have been evaluated after the fractionation of the red cells into five age groups by density gradient centrifugation. The glycoconjugate fractions studied included sialoglycoproteins, macroglycolipids, low-molecular-weight glycolipids, and Band 3 glycoproteins. All of the carbohydrate constituents of the membrane were found to decrease relative to the total ghost protein as a function of cell age, with the most substantial losses occurring in the macroglycolipids (50%) and Band 3 glycoprotein (30%); the smallest changes were observed in the sialoglycoproteins (13%). No preferential loss of sialic acid or other peripheral sugars was found, making unlikely the importance of glycosidase action in the removal of sugars from the membrane. It is suggested that the changes observed in the composition of the ghosts during aging are best explained by a loss of membrane segments enriched in glycoproteins and glycolipids and deficient in internally located molecules such as spectrin. Analyses were also performed on the glycoconjugate fractions from diabetic erythrocytes separated according to cell age. These erythrocytes, which had glycosylated hemoglobin values twice those of normals, had somewhat smaller amounts of membrane-bound carbohydrate. The difference between diabetic and normal erythrocytes was greatest when young cells were examined (diabetic to normal = 0.93), suggesting that the known increased turnover of red cells in diabetes leads to an early loss of membrane constituents.

Carbohydrates↗
PubMed1986

Binding of wheat-germ agglutinin to glycoconjugates in the salivary glands of reserpinized rats.

Salivary glands from adult rats that had received reserpine for 1, 3 or 7 days and from saline-treated controls were treated with rhodamine-labelled wheat-germ agglutinin conjugates (WGA-TRITC) to localize and characterize the distribution of glycoconjugates. Fluorescent and morphometric analysis of the parotid, submandibular and sublingual glands indicated that each gland responded differently to reserpine treatment. Parotid gland acinar cells and ducts showed no change in pattern or intensity of WGA-TRITC staining after reserpine. Mucous acinar cells of the submandibular gland had increased WGA binding and an accumulation of WGA-positive material in duct lumina after 3-7 days of reserpine. Morphometric analysis showed that the maximal increase in submandibular acinar-cell size occurred after 1 day of reserpine treatment. In sublingual glands, there was no detectable increase in mucous acinar-cell staining, but progressive accumulation of WGA-positive material was seen in duct lumina after 7 days of reserpine. As WGA binds to N-acetyl-glucosamine and N-acetyl-neuraminic acid residues, it may be that the eventual blockage of the duct system is related to increased production and secretion of glycoconjugates that contain these carbohydrates.

Animals↗
PubMed1983

Use of 6-diazo-5-oxo-L-norleucine to study interaction between myocardial glycoconjugate secretion and endothelial activation in the early embryonic chick heart.

The glutamine analog, 6-diazo-5-oxo-L-norleucine (DON), a glycoconjugate inhibitor, was used to probe the relationships between myocardial secretion of extracellular matrix and endothelial differentiation and formation of cushion mesenchyme (primordia of A V values). When DON was given to stage 12 chick embryos maintained in shell-less culture, the myocardial secretion gradient of glucose- and sulfate-labeled matrix was blocked. Concomitantly, the endothelium failed to complete activation but continued to divide and incorporate thymidine. By varying DON concentration, two distinct phases of endothelial differentiation were identified: the first (labile to 0.5 micrograms) involved hypertrophy, the second (labile to 0.25 micrograms) acquisition of migratory appendages with resultant mesenchyme formation. Glucosamine + DON (but not inosine, glucose, or glutamine) restored the matrical secretion gradient and to varying degrees both phases of endothelial activation. Endothelia totally suppressed from forming mesenchyme in situ acquired this capacity when explanted into three-dimensional collagen gel culture. The capacity was enhanced by glucosamine given in situ as an inhibitory override, dependent upon serum concentration, inhibited by heat-inactivated serum or by adding DON to the medium, but unaffected by hyaluronate. These results were compared to those obtained by co-culturing endothelium and myocardium and discussed in terms of the hypothesis that cushion mesenchyme formation results from an epithelial interaction mediated by glycoconjugates.

Animals↗
PubMed1983

Internalization and recycling of plasma membrane glycoconjugates during pinocytosis in the macrophage cell line, P388D1. Kinetic evidence for compartmentation of internalized membranes.

An analysis was made of the pinocytosis-derived internalization and recycling of membrane in the macrophage cell line, P388D1. Plasma membrane glycoconjugates, reversibly labelled with [3H]galactose, were used as a membrane marker. Label internalized with the plasma membrane was no longer accessible to release by externally added beta-galactosidase and could therefore be distinguished quantitatively from label remaining on the cell surface. Direct experimental evidence for membrane recycling was obtained by demonstrating that previously internalized label reappeared at the cell surface. The composition of labelled membrane glycoconjugates, as analysed by SDS-polyacrylamide gel electrophoresis, remained unaltered before and after internalization. The label remained membrane-bound in an unmodified way during the entire period of 8 h investigated, corresponding to about twenty-four cycles of membrane flow. Membrane flow led to a steady-state distribution of label between the plasma membrane and intracellular membranes. The redistribution of label occurred with biphasic kinetics, which could be described as the sum of two exponential functions. This behavior is explained by presenting a model of membrane flow between the plasma membrane and two consecutive intracellular membrane compartments, which we assume to consist of pinosomal membranes and of pinosome-derived membrane of secondary lysosomes. The relative membrane surface areas turn out to be in the ratio of 100:12.5:7.3, respectively. At the observed rate of pinocytosis, the equivalent of the plasma membrane is internalized once every 21 min, in the form of primary pinosomes of the size 0.24 micrometer. The residence time of membranes in the pinosome compartment is about 3 min. The rate at which membranes enter the lysosomal compartment is 31 times lower than the rate of membrane internalization. We conclude that only 3% of the amount of membrane internalized at any one time subsequently enters the secondary lysosome compartment. After a residence time of 49 min this membrane fraction is finally recycled to the cell surface. The results are discussed in terms of mixing and sorting-out of pinosomal and lysosomal membranes.

Animals↗
PubMed1984

Stimulation of mouse bone marrow cell membrane glycoconjugate synthesis by colony stimulating factor (CSF): basis for a rapid, simple assay for CSF.

A new method is presented for assaying mouse colony stimulating factor (CSF) based on the presumption that one of the earliest events after the induction of differentiation or maturation is an increase in synthesis and/or turnover of glycoconjugates in the target cell plasma membranes which may be detected as an increase in incorporation of [3H]galactose into acid precipitates of these cells. Using mouse bone marrow cells cultured in microtiter plates, we show that addition of CSF indeed results in dose-dependent stimulation of incorporation of galactose into their membrane glycoconjugates. Maximum stimulation of galactose incorporation occurs between 16 and 24 h of culture in the presence of CSF. A comparison of the standard colony test with the galactose incorporation assay showed similar dose-response patterns with 2 different CSFs. In a 3-step separation of bone marrow cells, there was a parallel enrichment of target cells for both assays. Furthermore, [3H]galactose-labeled marrow cells from our assay formed a discrete subpopulation which banded at a density of 1.065 g/cm3 on a linear gradient, and which contained all the identifiable CFU-c when further cultured in soft agar. The galactose incorporation assay does not require special medium or serum, and is simpler and quicker than the colony test. In comparative experiments it is demonstrated that this new 24 h assay is also reliable for screening CSF during purification procedures.

Animals↗
PubMed1988

Glycoconjugates as noninvasive probes of intrahepatic metabolism: III. Application to galactose assimilation by the intact rat.

A tracer methodology has been developed for noninvasive assessment of intrahepatic metabolism of administered labeled sugars. In this procedure, we measure the output of the label from the liver in two glycoconjugates derived from hepatic UDP-glucose, namely, glucuronic acid formed through UDP-glucuronic acid and excreted in the urine following acetaminophen administration, and galactose formed through UDP-galactose and then secreted in the carbohydrate portion of glycoproteins in the plasma. Comparison of the distribution of label from various sugar precursors in these end-products can indicate exchanges between hepatic UDP-glucose, UDP-galactose, and UDP-glucuronic acid. In this study we apply the technique to explore whether the enzyme UDP-galactose-4-epimerase catalyzing the step UDP-galactose to UDP-glucose is nonequilibrium and therefore potentially has a regulatory role for utilization of free galactose. The specific activity in the two glycoconjugates was compared when either [1-3H]galactose or [U-14C]glucose was the infused precursor sugar. In rats under a variety of conditions (fasting, oral refeeding, intravenous administration of galactose), label from [1-3H]galactose accumulated in glycoprotein-bound galactose much more than in acetaminophen-bound glucuronic acid, in comparison to label from [U-14C]glucose, demonstrating limitation of the rate of transfer from UDP-galactose to UDP-glucose at the epimerase step. Accordingly, epimerase is suggested to have a regulatory role in the galactose assimilation pathway.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1987

Abnormal glial and glycoconjugate dispositions in the somatosensory cortical barrel field of the early postnatal reeler mutant mouse.

During early postnatal development in reeler mutant mice, lectin binding delineates prospective abnormal barrels as they will appear in the adult mutant somatosensory cortex. Glial fibers also may be more condensed within fascicles in developing reeler barrels. These fibers also appear to be misaligned, coursing predominantly in the tangential plane within the abnormal reeler barrel sides as opposed to having a radial orientation as seen in normal mouse barrels. The thalamic barreloid complex, however, reveals a disposition of glycoconjugates that is completely normal in reeler. Thus, there are anomalies in glia and associated glycoconjugates during mainly cortical development in the reeler mutant mouse that might be related to the primary action of the abnormal gene.

Animals↗
PubMed1992

Developmental changes of fucosylated glycoconjugates in rabbit dorsal root ganglia.

Developmental changes of the fucosylated glycoconjugates in the dorsal root ganglia (DRG) of the rabbit were investigated histochemically using anti-fucosyl GM1 antibody and Ulex europaeus agglutinin 1 (UEA-1) lectin. Neither anti-fucosyl GM1 antibody nor UEA-1 lectin bound to the neural tubes or to the neural crest on embryonic day 14 (E14). Anti-fucosyl GM1 antibody binds diffusely to the DRG of E25. Large neurons unreactive with anti-fucosyl GM1 antibody appeared at 1 month and increased within 6 months after birth. Schwann cells immunoreactive with anti-fucosyl GM1 antibody came to be limited to the satellite cells surrounding the positive neurons. No staining with UEA-1 lectin was observed in the DRG of E25. Some small neurons became reactive with UEA-1 lectin within 1 month and remained to be so at 6 months after birth. Schwann cells including satellite cells were unreactive with this lectin. Since fucosyl GM1 was detected in the lipid fraction of DRGs from 1-month-old and 6-month-old rabbits, fucosyl GM1 itself should be the antigen molecule recognized by the anti-fucosyl GM1 antibody. Further study is necessary to elucidate the association between these developmental changes of the fucosylated glycoconjugates in DRG and their possible functional roles.

Animals↗
PubMed1996

Human brain beta-secretase contains heparan sulfate glycoconjugates.

A polyclonal antibody against the 68 kDa beta-secretase was established, which recognizes a single 68 kDa band in brain homogenate of Alzheimer's disease patients and normal aged. Western analysis revealed that the protease is an acidic glycoprotein with negative charge on its glycoconjugate(s). Sensitiveness to heparitinase and glycopeptidase A indicates that the protease contains asparagine-linked oligosaccharide with heparan sulfate moieties. Specific detection of the 68 kDa band in the analysis using anti-heparan sulfate antibody, and its time-course-dependent degradation, also confirm the above results. It seems that, like human blood coagulation factors IXa and XIa, the glycoconjugate(s) attached to the protease interfere with substrate specificity, stability and topological restriction of proteolysis in brain extracellular matrix, where diffuse plaque formation is taking place.

Aged↗
PubMed1985

Comparative compositions of cell surface glycoconjugates isolated from Trypanosoma cruzi epimastigotes.

Cell surface glycoconjugates of epimastigotes of Trypanosoma cruzi have been isolated and analyzed to give their amino acid and carbohydrate compositions. Those which have been investigated are a complex of three closely associated glycoproteins, GP24, GP31, GP37, and a lipopeptidophosphoglycan. The GP24-GP31-GP37 complex has an unusual amino acid composition with very low levels of hydrophobic amino acids, it contains 56% (w/w) carbohydrate, with mannose, galactose and glucosamine (presumably N-acetyl) being present in approximately equal quantities. The lipopeptidophosphoglycan also has low levels of hydrophobic amino acids and contains equal levels of mannose and galactose together with lesser amounts of (N-acetyl) glucosamine. The glycoconjugates are contrasted and compared with two other previously characterised cell surface glycoproteins (GP25 and GP72) from T. cruzi.

Amino Acids↗
PubMed1982

The glycoconjugates from Trypanosoma Cruzi, purification and composition of a glycoprotein.

1. The complex of glycoconjugates extracted with phenol-water from culture epimastigotes of a non-infective line (To) of Trypanosoma cruzi, derived from the Tulahuén strain showed only two components by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. 2. The slower migrating glycoconjugate, a glycoprotein of molecular weight 45, 000 was purified to apparent homogeneity. 3. A content of 76% protein, 17% neutral sugars and 6% glucosamine was analysed. Galactose and mannose occur in a ratio of 3:1 as determined by gas-liquid chromatography. A trace of glucose was detected in some samples.

Animals↗
PubMed1987

Leptomonas samueli glycoconjugates. Comparison with Herpetomonas samuelpessoai.

Xylose and mannose are the main manosaccharide components of Herpetomonas samuelpessoai and Leptomonas samueli promastigotes. Variations in the xylose/mannose ratios are related to the age of cultures. Phenol-aqueous extraction disclosed in both species the presence of carbohydrate-containing fractions which were both soluble and insoluble in chloroform/methanol/water (10:10.3). The xylose enriched, uronic acid-containing glycoconjugates of L. samueli were mainly composed of (1----4)-linked xylose units (Methylation-mass spectrometry and 13C NMR), similar to the glucuronoxylan of H. samuelpessoai (Mendonça-Previato et al., 1979 Biochem 18 149-154). SDS-PAGE and sugar composition analysis disclosed similarities between glycoconjugates of H. samuelpessoai and L. samueli, two species dwelling in the same host, therefore an example of convergent adaptation.

Animals↗