SEARCH · Search PubMed

Results for “GLYCOLIPIDS”

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.

SourceResearch connectionFrom yearThrough year

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

At least 865 records · Page 48Linked to original sources

PubMed1979

A method for the determination of the chemical structure of glycolipids biosynthesized in vitro and the specificity and activity of glycosyltransferases.

A very sensitive method for the qualitative and quantitative investigation of the biosynthesis of the oligosaccharide chains of glycolipids in such tissues as cultured cells, biopsies, or cell organelles, is described. It permits the determination, on an ultramicro-scale, of the specificity of glycosyltransferases in terms of the exact chemical structure of the products that are synthesized from known labeled glycolipid precursors, and defines without ambiguity the precursor-to-product relationship in biosynthetic incubations in vitro.

Cells, Cultured↗

PubMed2002

Synthesis and inhibitory activity of a di- and a trisaccharide corresponding to an erythrocyte glycolipid responsible for the nor polyagglutination.

The polyagglutinable erythrocytes NOR contain unusual neutral glycolipids reactive with anti-NOR antibodies. The disaccharide alpha-D-Galp-(1-->4)-D-GalpNAc and the trisaccharide alpha-D-Galp-(1-->4)-beta-D-GalpNAc-(1-->3)-D-Gal corresponding to the non-reducing end of a NOR glycolipid (NOR1) were chemically synthesized. The syntheses were based on a common (1-->4)-beta-D-GalNAc precursor, and utilized benzyl glycoside and benzyl ether functions for persistent blocking of hydroxyls. The alpha-D-Galp-(1-->4)-beta-D-GalpNAc structural element has been found only recently in Nature, and derivatives thereof have not been synthesized before. Both the synthesized oligosaccharides inhibited specifically human anti-NOR antibodies, the trisaccharide being 300 times more active than the disaccharide.

Carbohydrate Sequence↗

PubMed1996

Structural studies of the major glycolipid from Saccharopolyspora genus.

A major glycolipid was isolated from the well characterized Saccharopolyspora species, S. hirsuta, S. rectivirgula, S. erythraea and one not completely identified strain (Saccharopolyspora sp.). On the basis of sugar and methylation analysis, specific enzymatic and chemical degradations of the carbohydrate moiety, its FAB mass spectrometry and NMR spectroscopy characterizations, the carbohydrate part was shown to be the glycerol linked dimannoside alpha-D-Manp-(1-->3)-alpha-D-Manp-(1-->1/3)Gro. The internal mannose residue is esterified at C-6 by one fatty acid residue, whereas another fatty acyl chain substitutes the primary methylene position of glycerol. The main fatty acyl residues are anteiso-branched heptadecanoic acid and the iso-branched fatty acids iso-17:0, iso-16:0, and iso-18:0, with the former species being predominant. The major glycolipid has potential value for taxonomic and diagnostic purposes, especially in the specific diagnosis of farmer's lung disease.

Carbohydrate Conformation↗

PubMed2003

Glycolipids of the filamentous fungus Absidia corymbifera F-295.

The lipids extracted with CHCl(3)/MeOH mixtures from mycelium of the lower filamentous fungus Absidia corymbifera F-295 were found to contain three glycolipids. Based on the IR, 1H and 13C NMR spectra, plasma-desorption ionisation (PDI) mass spectra as well as chemical degradation results, the glycolipids were established to be 1-O-beta-D-glucopyranosyl-2-N-(2'-D-hydroxyhexadecanoyl)-9-methylsphinga-4(E),8(E)-dienine (glucosyl ceramide) and 2-O-(6'-O-beta-D-galactopyranosyl)-beta-D-galactopyranosides of 2-D-hydroxy and erythro-2,3-dihydroxy fatty acids C(9), C(11), and C(13). They accounted for about 3.4, 0.8, and 0.4%, respectively, of the total lipids extracted. No lipids identical to the above monohydroxy and dihydroxy fatty acid glycosides have been reported.

Absidia↗

PubMed1998

Total glycolipid and glucosylceramide content in serum and urine of patients with Gaucher's disease type 3 before and after enzyme replacement therapy.

The follow-up of Gaucher's patients under enzyme replacement therapy is generally based both on the clinical aspects and the evaluation of haematological parameters: haemoglobin level, platelet count, acid and alkaline phosphatase activities. Spleen and liver volumes are also reliable criteria for evaluating the improvement of the patients. The determination of glycolipid excretion in the urine and/or the quantification of glycolipids in serum can also be a useful tool for the screening and the follow up of patients with lysosomal storage disease including Gaucher's disease. In this paper we report the follow-up of three patients with Gaucher type 3; in order to test the efficacy of the enzyme replacement therapy with alglucerase in these patients, we evaluated the urine and plasma glucosylceramide content as a marker parallel to the clinical improvement and the decreased organomegaly.

Child↗

PubMed1999

Transcytosis of immunoglobulin A in the mouse enterocyte occurs through glycolipid raft- and rab17-containing compartments.

BACKGROUND & AIMS: Glycolipid "rafts" have been shown to play a role in apical membrane trafficking in the enterocyte. The present study characterized the membrane compartments of the enterocyte involved in transepithelial transport of small intestinal immunoglobulin A (IgA). METHODS: Immunogold electron microscopy and radioactive labeling of mouse small intestinal explants were performed. RESULTS: IgA and the polymeric immunoglobulin receptor/secretory component were present in a raft compartment. Raft association occurred posttranslationally within 30 minutes, preceding secretion into the culture medium. IgA labeling was seen primarily in enterocytes along the basolateral plasma membrane and over endosomes and small vesicles in the basolateral and apical regions of the cytoplasm. IgA and a brush border enzyme, aminopeptidase N, were colocalized in apical endosomes and small vesicles and were also frequently seen associated with the same vesicular profiles of glycolipid rafts. Colocalization of IgA and rab17, a small guanosine triphosphatase involved in transcytosis, was seen mainly along the basolateral plasma membrane and over basolateral endosomes and vesicles, but also in the apical region of the cytoplasm. CONCLUSIONS: IgA is transcytosed through a raft-containing compartment, most likely the apical endosomes. Our data also support the notion that rab17 is involved in transcytotic membrane traffic.

Amino Acid Sequence↗

PubMed1987

Analysis of ceramide and monohexaosyl glycolipid derivatives by high-performance liquid chromatography and its application to the determination of the molecular species in tissues.

Several molecular species of monohexaosyl glycolipids and ceramides were analyzed as their benzoyl derivatives by high-performance liquid chromatography on a silica column with mixtures of dioxane and hexane as eluents. Monohexaosyl glycolipid derivatives were classified according to their hydrophobic structures, and ceramides were separated based on the fatty acid groups and the long-chain bases. The method allowed us to observe the heterogeneities in the molecular species of cerebrosides and ceramides from the epidermis and dermis of the guinea pig, and clear differences in the molecular species were observed between the different regions.

Animals↗

PubMed2000

Quantitative analyses of binding affinity and specificity for glycolipid receptors by surface plasmon resonance.

In recent years, rapid expansion has been seen of the application of SPR to a wide range of biomolecular interactions. For protein-carbohydrate interactions, SPR techniques offer the means of presenting glycolipids, and potentially glycoproteins, in an environment that closely resembles their in vivo situation. It is already clear that the technology can provide much additional insight into these interactions because it monitors the interactions under conditions that approach physiologic ones and can allow for the investigation of parameters that are not accessible by conventional approaches. Strategies for the immobilization of glycolipids on BIACORE sensor chips are not limited to the two approaches described here. For example, liposomes containing biotinylated phospholipid could be captured by avidin or streptavidin surfaces; this strategy has been used for the capture of natural membrane vesicles. Also, Biacore AB has announced plans to introduce a version of the CM5 chip that has been derivatized with an undisclosed group that mediates the capture of large amounts of liposomes.

Animals↗

PubMed1998

Glycolipids as potential binding sites for HIV: topology in the sperm plasma membrane in relation to the regulation of membrane fusion.

Although human sperm cells can bind human immunodeficiency virus (HIV-1), they lack CD4, galactoceramides (GalCer) and sulfogalactoceramides (SGalCer) as gp120 receptors. However, sperm specific glycolipids (sulfogalactosylalkylacylglycerol (SGalAAG) and galactosylalkylacylglycerol (GalAAG)) are structurally closely related to SGalCer and GalCer as predicted by computer simulated molecular modelling. SGalAAG and GalAAG are exclusively localized in the outer leaflet of the human sperm plasma membrane, and therefore we tested whether they could serve as alternative receptors for the gp120. Purified SGalAAG and GalAAG had similar affinities to recombinant gp120 as the hydroxy fatty acid (HFA) SGalCer and HFA-GalCer respectively. However, nonhydroxy fatty acid forms of (S)GalCer, galactosyldiacylglycerol and the deacylated (sulfo)galactosyllipids did not recognize recombinant gp120. Data obtained by surface pressure experiments revealed that the lipid monolayers that contained HFA-GalCer or GalAAG resulted in a similar significant penetration of recombinant gp120 in the monolayer. The penetration was a factor of two lower in monolayers with HFA-SGalCer or SGalAAG. The binding of recombinant gp120 to human sperm cells colocalized with GalAAG and could be blocked with monoclonal antibodies against galactolipids. The possible relevance of gp120 binding to glycolipids for HIV entry in sperm cells is discussed.

Cell Membrane↗

PubMed2002

Generation and characterization of antibodies to sulfated glucuronyl glycolipids in Lewis rats.

Antibodies to sulfated glucuronyl glycolipids (SGGLs) have been reported in sera of patients with peripheral neuropathies including patients with IgM gammopathy. However, the role of anti-SGGL antibodies in the pathogenesis of neuropathy remains unclear. In order to study the role of antibodies to SGGLs in the pathogenesis of neuropathy, Lewis female rats were injected with purified SGPG mixed with keyhole limpet hemocyanin (KLH) and emulsified with equal amount of complete Freund's adjuvant. High titer anti-SGPG antibodies were detected by ELISA in sera of all rats inoculated with SGPG. All anti-SGPG antibodies cross-reacted with human myelin-associated glycoprotein (MAG). None of the sensitized rats exhibited clinical signs of neuropathy. Histological examination showed that there was no demyelination or axonal damage in peripheral nerves. Our data demonstrate that SGPG is a highly immunogenic glycolipid but high titer antibodies against it do not produce an experimental autoimmune neuropathy in Lewis rats.

Animals↗

PubMed1997

Characterization of the affinity of the G(M2) activator protein for glycolipids by a fluorescence dequenching assay.

The G(M2) activator protein is a substrate specific cofactor for degradation of G(M2) ganglioside by lysosomal beta-hexosaminidase A. Mutations in the gene encoding the activator result in the AB-variant form of G(M2) gangliosidosis. The activator protein contains at least three functional elements; a hydrophobic binding pocket, an oligosaccharide binding site(s), and an area that interacts with hexosaminidase A. In this report a fluorescence dequenching assay specific for only the hydrophobic binding pocket is evaluated and optimized. It is shown that various glycolipids inhibit the transport between liposomes of a self-quenching fluorescent lipid probe, octadecylrhodamine, by the activator protein. The level of inhibition produced by each glycolipid is then used to characterize the oligosaccharide-binding specificity of the activator. The fluorescence dequenching assay is also used to evaluate the functionality of a truncated form of the activator protein. Our results indicate that this simple assay can be used to determine structure-function relationships within the normal or mutant forms of the activator. The data suggest that the C-terminus of the activator is required to produce a functional hydrophobic binding pocket.

Binding Sites↗

PubMedDate not supplied

Glycolipid antigen for use in diagnostic assays for bovine tuberculosis.

A glycolipid antigen, was isolated, purified and characterized from Mycobacterium bovis An5. Chemical analysis (thin-layer chromatography, nuclear magnetic resonance and infrared spectra) showed that this glycolipid was a 2,3-di-O-acyl trehalose (DAT), similar to the DAT of M. tuberculosis. This antigen was used to establish ELISA-based serodiagnostic tests for M. bovis-infected cattle. The sensitivity and specificity of the assay were investigated using sera of cattle from tuberculosis-free herds and from tuberculosis-infected herds. No correlation was found between DAT-ELISA and the skin test, nor between DAT-ELISA and interferon-gamma with bovine purified protein derivative. The antibody titres were not related to cell-mediated immunity. Although the antigen was highly specific (95.9%), the sensitivity of DAT-ELISA, as judged from assays in bacteriologically confirmed tuberculosis, was low (29 to 36.8%). The low sensitivity of ELISA might also be attributed to a reciprocal relationship between B-cell proliferation and T-cell protective immunity.

Animals↗

PubMed1998

Membrane biology: do glycolipid microdomains really exist?

Glycolipid membrane domains have been suggested to have a number of physiological functions, but do they actually exist in vivo or are they artefacts of extraction procedures? Recent data go some way towards showing that such glycolipid domains really are present within both model and cellular membranes.

Cell Membrane↗

PubMed1989

Malignant cell glycoproteins and glycolipids.

The cell surface is involved in cell growth and division, cell-cell interaction, communication, differentiation and migration, and other processes likely to be involved in malignant transformation and/or the metastatic spread of cancer. Although there are many alterations of glycoproteins and glycolipids on the malignant cell surface, it is unclear whether these alterations are epiphenomena or an integral part of the malignancy process. This article reviews the recent literature and some earlier studies relevant for understanding emerging concepts and trends with respect to malignant cell glycoconjugates. Emphasis is on structural alterations of the carbohydrate portions of malignant cell glycoproteins and glycolipids and on the enzymes (glycosyltransferases and glycosidases) involved in their metabolism. Practical applications derived from malignant cell glycoconjugate studies are discussed briefly with respect to the diagnosis, staging, monitoring, and treatment of malignant disease. The review concludes by indicating which research areas on malignant cell glycoconjugates are likely to be fruitful in increasing our basic understanding of, and ability to deal effectively with, malignant disease.

Animals↗

PubMed1998

Localization of glycolipids in membranes by in vivo labeling and neutron diffraction.

Evidence is accumulating for the lateral organization of cell membrane lipids and proteins in the context of sorting or intracellular signaling. So far, however, information has been lacking on the details of protein-lipid interactions in such aggregates. Purple membranes are patches made up of lipids and the protein bacteriorhodopsin in the plasma membrane of certain Archaea. Naturally crystalline, they provide a unique opportunity to study the structure of a natural membrane at submolecular resolution by diffraction methods. We present a direct structural determination of the glycolipids with respect to bacteriorhodopsin in these membranes. Deuterium labels incorporated in vivo into the sugar moieties of the major glycolipid were localized by neutron diffraction. The data suggest a role for specific aromatic residue-carbohydrate stacking interactions in the formation of the purple membrane crystalline patches.

Amino Acids↗

PubMed1995

Common links in the structure and cellular localization of Rhizobium chitolipooligosaccharides and general Rhizobium membrane phospholipid and glycolipid components.

Several common links between the structural chemistry of the chitolipooligosaccharides of Rhizobium and the general rhizobial membrane lipid and lipopolysaccharide chemistry of these bacteria have been uncovered. Aspects of common chemistry include sulfation, methylation, and the position and extent of fatty acyl chain unsaturation. We find that bacteria which are known to synthesize sulfated chitolipooligosaccharides (such as Rhizobium meliloti strains and the broad-host-range Rhizobium species strain NGR234) also have sulfated lipopolysaccharides. Their common origins of sulfation have been demonstrated by using mutants which are known to be impaired in sulfating their chitolipooligosaccharides. In such cases, there is a corresponding diminution or complete lack of sulfation of the lipopolysaccharides. The structural diversity of the fatty acids observed in the chitolipooligosaccharides is also observed in the other membrane lipids. For instance, the doubly unsaturated fatty acids which are known to be predominant components of R. meliloti chitolipooligosaccharides were also found in the usual phospholipids and glycolipids. Also, the known functionalization of the chitolipooligosaccharides of R. sp. NGR234 by O- and N-methylation was also reflected in the lipopolysaccharide of this organism. The common structural features of chitolipooligosaccharides and membrane components are consistent with a substantial degree of biosynthetic overlap and a large degree of cellular, spatial overlap between these molecules. The latter aspect is clearly demonstrated here since we show that the chitolipooligosaccharides are, in fact, normal membrane components of Rhizobium. This increases the importance of understanding the role of the bacterial cell surface chemistry in the Rhizobium/legume symbiosis and developing a comprehensive understanding of the highly integrated membrane lipid and glycolipid chemistry of Rhizobium.

Carbohydrate Conformation↗

PubMed1991

Stereochemistry and size of sugar head groups determine structure and phase behavior of glycolipid membranes: densitometric, calorimetric, and X-ray studies.

The role carbohydrate moieties play in determining the structure and energetics of glycolipid model membranes has been investigated by small- and wide-angle X-ray scattering, differential scanning densitometry (DSD), and differential scanning microcalorimetry (DSC). The dependence of a variety of thermodynamic and structural parameters on the stereochemistry of the OH groups in the pyranose ring and on the size of the sugar head group has been studied by using an homologous series of synthetic stereochemically uniform glyceroglycolipids having glucose, galactose, mannose, maltose, or trimaltose head groups and saturated ether-linked alkyl chains with 10, 12, 14, 16, or 18 carbon atoms per chain. The combined structural and thermodynamic data indicate that stereochemical changes of a single OH group in the pyranose ring can cause dramatic alterations in the stability and in the nature of the phase transitions of the membranes. The second equally important determinant of lipid interactions in the membrane is the size of the head group. A comparison of lipids with glucose, maltose, or trimaltose head groups and identical hydrophobic moieties has shown that increasing the size of the neutral carbohydrate head group strongly favors the bilayer-forming tendency of the glycolipids. These experimental results provide a verification of the geometric model advanced by Israelachvili et al. (1980) [Israelachvili, J. N., Marcelja, S., & Horn, R. G. (1980) Q. Rev. Biophys. 13, 121-200] to explain the preferences lipids exhibit for certain structures. Generally galactose head groups confer highest stability on the multilamellar model membranes as judged on the basis of the chain-melting transition. This is an interesting aspect in view of the fact that galactose moieties are frequently observed in membranes of thermophilic organisms. Glucose head groups provide lower stability but increase the number of stable intermediate structures that the corresponding lipids can adopt. Galactolipids do not even assume a stable intermediate L alpha phase for lipids with short chain length but perform only Lc----HII transitions in the first heating. The C2 isomer, mannose, modifies the phase preference in such a manner that only L beta----HII changes can occur. Maltose and trimaltose head groups prevent the adoption of the HII phase and permit only L beta----L alpha phase changes. The DSD studies resulted in a quantitative estimate for the volume change associated with the L alpha----HII transition of 14-Glc. The value of delta v = 0.005 mL/g supports the view that the volume difference between L alpha and HII is minute.(ABSTRACT TRUNCATED AT 400 WORDS)

Calorimetry, Differential Scanning↗

PubMed1984

Glycolipid transfer protein from bovine brain.

Glycolipid transfer protein from bovine brain has been purified partially by ammonium sulfate precipitation, CM-52 ion-exchange, and Sephadex G-75 column chromatography. Both pyrene-labeled and tritium-labeled glucocerebrosides have been used to study the kinetics of protein-mediated transfer between donor and acceptor vesicles. Protein accelerates glucocerebroside transfer but does not accelerate phospholipid transfer. In colyophilized small sonicated vesicles (10% glucocerebroside, 90% 1-palmitoyl-2-oleoyl-phosphatidylcholine) about two-thirds of the glycolipid is transferred in 2 h and the remaining one-third does not transfer (up to 5 h). For donor and acceptor vesicles made of dipalmitoylphosphatidylcholine or 1-palmitoyl-2-oleoyl-phosphatidylcholine, glucocerebroside (10% in donors) is transferred rapidly only when both the donor and acceptor matrix phospholipids are in the liquid-crystalline state. If either donor or acceptor vesicles are in the gel state, transfer protein mediated transfer is much reduced. The amount of transfer protein bound specifically to glucocerebroside-containing vesicles is nearly equal above and below the matrix phospholipid phase transition temperature. Bound protein transfers glucocerebroside upon addition of acceptor vesicles.

Animals↗