Search PubMed⌕ Search

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.

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

At least 703 records · Page 39Linked to original sources
PubMed2004

The crystal structure of human CD1b with a bound bacterial glycolipid.

The human MHC class I-like molecule CD1b is distinctive among CD1 alleles in that it is capable of presenting a set of glycolipid species that show a very broad range of variation in the lengths of their acyl chains. A structure of CD1b complexed with relatively short acyl chain glycolipids plus detergent suggested how an interlinked network of channels within the Ag-binding groove could accommodate acyl chain lengths of up to 80 carbons. The structure of CD1b complexed with glucose monomycolate, reported in this study, confirms this hypothesis and illustrates how the distinctive substituents of intracellular bacterial glycolipids can be accommodated. The Ag-binding groove of CD1b is, uniquely among CD1 alleles, partitioned into channels suitable for the compact accommodation of lengthy acyl chains. The current crystal structure illustrates for the first time the binding of a natural bacterial lipid Ag to CD1b and shows how its novel structural features fit this molecule for its role in the immune response to intracellular bacteria.

Amino Acid Sequence↗
PubMed1999

Dynamics of glycolipid domains in the plasma membrane of living cultured neurons, following protein kinase C activation: a study performed by excimer-formation imaging.

Dynamic changes of glycolipid domains within the plasma membranes of cultured rat cerebellar granule cells have been investigated. For this purpose, a pyrene-labelled derivative of G(M1) ganglioside has been incorporated in the cell plasma membrane, and the rate of excimer formation, directly related to the formation of domains, has been studied by a fluorescence imaging technique (excimer-formation imaging). Fluorescence imaging showed that upon addition of 100 microM glutamate, indirectly inducing the activation of protein kinase C (PKC), glycolipid concentration within domains increases in cell bodies. Comparable effects were exerted by the addition of PMA, directly inducing the activation of PKC. On the contrary, the phorbol ester was not effective in the presence of the specific PKC inhibitor, bisindolylmaleimide. These results suggest that glycolipid-enriched domains are dynamic supramolecular structures affected by membrane-associated events, such as PKC activation. Dynamic changes of domains could be important in modulating their postulated participation in a series of functions, including signal transduction and lipid/protein sorting.

Animals↗
PubMed2001

Human sperm motility stimulating activity of a sulfono glycolipid isolated from Sri Lankan marine red alga Gelidiella acerosa.

AIM: To evaluate the sperm motility stimulating activity of a sulfono glycolipid (S-ACT-1) isolated from Gelidiella acerosa, a Sri Lankan marine red algae. METHODS: S-ACT-1, a white amorphous powder was separated from more polar fractions of the hexane soluble of 1:1 CH2Cl2/MeOH extract and subjected to 1H, 13C NMR and IR Spectroscopy after reverse phase HPLC for identification. Effects of S-ACT-1 on human sperm motility was assessed in vitro at 10, 100 and 1,000 microg/mL concentrations at 37 degrees C for 0, 5, 15, 30 and 60 min. RESULTS: S-ACT-1 was identified as a glycolipid sulfate. The lower dose increased the sperm motility slightly, whilst the medium dose significantly increased the motility (P < 0.05) from 5 min of incubation reaching a peak at 15 min and the stimulant effect was sustained throughout the experimental period. Furthermore, the medium dose rendered 80% of the immotile viable sperm motile. In contrast, the highest dose impaired the sperm motility. The sperm stimulating activity of S-ACT-1 was dose-dependent and had a bell-shaped dose response curve for all the 5 incubation periods. CONCLUSION: S-ACT-1 of Gelidiella acerosa is a Sulfono glycolipid. S-ACT-1 has a potent sperm motility stimulating activity in vitro and has the potential to be developed into a sperm stimulant.

Analysis of Variance↗
PubMed2001

Postnatal changes in the brain lipids, glycolipids and gangliosides of rats exposed to arrack/ethanol during gestation and lactation.

Effects of exposure of an alcoholic beverage (arrack and its equivalent quantity of alcohol throughout pregnancy and lactation on brain lipids were investigated. Female rats were exposed to arrack (12.00 ml/kg body weigh/day) and ethanol (4.00 g/kg body weight day) before conception and throughout gestation and lactation. For 21 days pups were nursed by their own mothers, afterwards they were fed normal laboratory feed. We found that the level of cholesterol, phospholipids, triacylglycerols, free fatty acids, cerebrosides, ceramide dihexosides, ceramide polyhexosides, sulfatids,, mono and diglycosyl diglycerides and gangliosides were increased in the brain of 21st and 45th day pups. The alterations in the glycolipid profile of the brain persisted even when pups were not directly exposed to alcohol. These alterations in the glycolipid and ganglioside metabolism may be associated with the developmental abnormalities of the brain seen in FAS. The elevation produced in the glycolipid profile of arrack administered pups were more than that caused by its equivalent quantity of ethanol. This suggested an interaction of congeners in the arrack with the alcohol.

Animals↗
PubMed1992

Biosynthesis of glycolipid precursors for glycosylphosphatidylinositol membrane anchors in a Toxoplasma gondii cell-free system.

Toxoplasmosis, a disease that affects humans and a wide variety of mammals is caused by Toxoplasma gondii, the obligate intracellular coccidian protozoan parasite. Most T. gondii research has focused on the rapidly growing invasive form, the tachyzoite, which expresses five major surface proteins attached to the parasite membrane by glycosylphosphatidylinositol (GPI) anchors. We have recently reported the purification and partial characterization of candidate precursor glycolipids (GPIs) from metabolically labeled parasites and have presented evidence that these GPIs have a linear glycan backbone sequence indistinguishable from the GPI core glycan of the major tachyzoite surface protein, P30. In this report, we describe a cell-free system derived from tachyzoite membranes which is capable of catalyzing GPI biosynthesis. Incubation of the membrane preparations with radioactive sugar nucleotides (GDP-[3H]mannose or UDP-[3H]GlcNAc) resulted in incorporation of radiolabeled into numerous glycolipids. By using a combination of chemical/enzymatic tests and chromatographic analysis, a series of incompletely glycosylated lipid species and mature GPIs have been identified. We have also established the involvement of Dol-P-mannose in the synthesis of T. gondii GPIs by demonstrating that the incorporation of [3H]mannose into the mannosylated GPIs is stimulated by dolichylphosphate and inhibited by amphomycin. In addition, increasing the concentration of nonradioactive GDP mannose resulted in a loss of radiolabel from the first easily detectable GPI precursor, GlcN-PI, and a concomittant appearance of the radio-activity into mannosylated glycolipids. Altogether, our data suggest that the GPI core glycan in T. gondii is assembled via sequential glycosylation of phosphatidylinositol, as proposed for the biosynthesis of GPIs in Trypanosoma brucei. In contrast to T. brucei, preliminary experiments indicate that the core glycan of some GPIs synthesized by the T. gondii cell-free system is modified by N-acetylgalactosamine similar to the situation for mammalian Thy-1.

Adenosine Triphosphate↗
PubMed1991

New types of glycolipids from the surface lipids of Nicotiana umbratica.

The surface lipids of Nicotiana umbratica contained several varieties of glycolipids. Three types of glucose esters and five types of sucrose esters were isolated and identified from this species. These glycolipids contained short-chain fatty acids such as acetic, methylpropionic, methylbutyric, 3-methylpentanoic, 4-methylpentanoic and methylhexanoic acids. The acetylated positions of each compound were determined by 2-D NMR, using the HMBC technique. The structures of the glucose esters were 1,6-di-O-acetyl-2,3-4-tri-O-acyl-alpha-D-glucopyranose (I), 6-O-acetyl-2,3,4-tri-O-acyl-alpha-D-glucopyranose (II) and 2,3,4-tri-O-acyl-alpha, beta-D-glucopyranose (III). The structures of the sucrose esters were 6-O-acetyl-2,3,4-tri-O-acyl-alpha-D-glucopyranosyl-1,3-di-O-acetyl-beta- D- fructofuranoside (IV), 2,3,4-tri-O-acyl-alpha-D-glucopyranosyl-1,3-di-O-acetyl-beta-D-fructofur anoside (V), 6-O-acetyl-2,4-di-O-acyl-alpha-D-glucopyranosyl-3-O-acetyl-beta-D- fructofuranoside (VI), 2,3,4-tri-O-acyl-alpha-D-glucopyranosyl-3-O-acetyl-beta-D-fructofuranosi de 2,3,4-tri-O-acyl-alpha-D-glucopyranosyl-3-O-acetyl-beta-D-fructofuranosi de (VII) and 2,3,4-tri-O-acyl-alpha-D-glucopyranosyl-beta-D-fructofuranoside (VIII). Among them, I, IV, V and VI were isolated for the first time from plants of the family Solanaceae. These newly isolated glycolipids were inhibitory against barnyardgrass growth.

Carbohydrate Sequence↗
PubMed1991

Developmental changes in the glycosylated phosphatidylinositols of Leishmania donovani. Characterization of the promastigote and amastigote glycolipids.

In addition to utilizing glycosylated phosphatidylinositols (GPIs) as anchors for surface proteins, protozoan parasites of the genus Leishmania synthesize two novel classes of GPI: the polydisperse lipophosphoglycans (LPGs) and a family of low molecular weight glycoinositol phospholipids (GIPLs). We now show that LPG is expressed in high copy number (6 x 10(6) molecules/cell) in the promastigote (insect) stage of L. donovani but not in the amastigote stage, which infects mammalian macrophages. Detection of these molecules was by gas chromatography-mass spectrometric analyses and by a sensitive radiolabeling procedure. In contrast, a novel family of GIPLs was present in high copy number (approximately 10(7) molecules/cell) in both promastigote and amastigote stages of L. donovani. These glycolipids were purified and analyzed by gas chromatography-mass spectrometry, methylation analysis, and by chemical and enzymatic sequencing after deamination and NaB3H4 reduction. Promastigotes contained three major GIPLs species with the following generalized structure [formula: see text] where R = H for isoM2, Man alpha 1- for isoM3 or Man alpha 1-2Man alpha 1- for isoM4. Amastigotes contained two major GIPL species that lacked the alpha 1-3-linked mannose branch and had the linear structures Man alpha 1-6Man alpha 1-4GlcN (M2) and Man alpha 1-2Man alpha 1-6Man alpha 1-4GlcN (M3) linked to alkylacyl-PI. The 1-O-alkyl-2-acyl-PI moieties of all these species contained predominantly C18:0 alkyl chains and C16:0 or C18:0 fatty acids. Amastigotes contained, in addition, a GalNAc beta 1-3 terminating glycosphingolipid with homology to the mammalian para Forssman glycolipid. This glycolipid appeared to be a constituent of the parasite membrane but was not metabolically labeled with [3H]glucose, suggesting that it was acquired from host cells. These results suggest that LPG may not be required for amastigote survival in the mammalian host and that the GIPLs are likely to be major components on the surface membrane in both stages.

Animals↗
PubMed1991

Sulfated glycolipids are the platelet autoantigens for human platelet-binding monoclonal anti-DNA autoantibodies.

The human monoclonal autoantibody HF2-1/17, produced by a human-human hybridoma derived from lymphocytes of a lupus patient with thrombocytopenia, reacts with single stranded DNA and platelets. To determine the chemical nature of the autoantigen against which this antibody is directed on platelets, this platelet antigen was purified by the lipid extraction of sonicated platelets, DEAE-Sephadex chromatography, and high performance liquid chromatography. The purified glycolipids, a trace component in platelets, demonstrated high reactivity with the HF2-1/17 antibody using a competition enzyme-linked immunosorbent assay system or immunostaining of thin layer chromatograms. The purified glycolipids co-migrated with bovine sulfatides by thin layer chromatography. The purified glycolipids contain sulfate and galactose but not sialic acid or phosphate. Fast atom bombardment-mass spectrometry revealed these sulfatides to be sulfated monohexyl ceramides. The dominant species has a molecular weight of 794 while a minor form has a molecular weight of 812 due to an extra hydroxyl group and loss of a double bond. These results indicate that the platelet autoantigen against which the human monoclonal anti-DNA antibody is directed represents a family of novel monogalactosyl sulfatides.

Antibodies, Monoclonal↗
PubMed1977

[Changes in the composition of glycolipids in N-nitrosomorpholine-induced hepatoma. The role of such substances in the plasma membrane of normal and neoplastic cells].

Malignant hepatomas induced in the rat by N-Nitrosomorpholine showed an absence of trisialogangliosides GT1 and, in some cases, also a decrease in disialoganglioside GD1a and monoganglioside GM1. Simultaneously there occurred an increase in a monoganglioside with a short oligosacharide chain GM3. Such deviations in the composition of glycolipids are in accordance with the literary data mentioning, as a general change, the presence of only some glycolipids as a result of a deficient synthesis of the oligosacharide part of their molecule. The differences in the glycolipid composition of the cell membrane as well as their different arrangement have been discussed with respect to some present views concerning the different behaviour of the neoplastic cell surfaces.

Animals↗
PubMed1990

Effect of glycolipids of Leishmania parasites on human monocyte activity. Inhibition by lipophosphoglycan.

Lipophosphoglycan (LPG) and glycosyl phosphatidylinositol Ag (GPI), are glycolipids present on the membrane of Leishmania parasites. Both glycolipids have been chemically characterized. LPG is a polysaccharide of repeating phosphorylated units linked to a phosphocarbohydrate core that is anchored to the membrane by lysoalkyl phosphatidylinositol (PI). The GPI are smaller glycolipids with a structure resembling the phosphocarbohydrate core of the LPG. They are anchored to the membrane by alkyl acyl PI. Their relative abundance, uniqueness of structure, and cellular location suggest a role in interactions of the parasites with host cells. In the present study we examined the effect of LPG and GPI on the activation of human peripheral blood monocytes. Three parameters were studied: the production of IL-1, chemotactic locomotion, and oxidative burst. We found that whereas neither GPI nor LPG directly affected monocyte activity, preincubation of the monocytes with LPG strongly inhibited further activation: The production of IL-1, after stimulation with LPS, was decreased in a dose-dependent manner. Previous incubation with LPG also inhibited chemotactic locomotion of monocytes and neutrophils in response to diacylglycerol, zymosan-activated serum, FMLP and LTB4. Luminol-dependent chemiluminiscence caused by stimulation of the monocytes with streptococci and histone was also inhibited. After fragmentation of the LPG into phosphoglycan and 1-O-alkylglycerol by phosphatidylinositol-phospholipase C, only the phosphoglycan retained inhibitory activity. No difference in inhibitory activity was found between LPG prepared from Leishmania major or Leishmania donovani promastigotes. These results show that the phosphoglycan of LPG inhibits the immunologic response of normal human monocytes and neutrophils, and suggest that LPG may influence the nature of the inflammatory response surrounding infected cells.

Animals↗
PubMed1987

Y and blood group B type 2 glycolipid antigens accumulate in a human gastric carcinoma cell line as detected by monoclonal antibody. Isolation and characterization by mass spectrometry and NMR spectroscopy.

A monoclonal antibody (mAb), BR55-2, was generated from mice immunized with MCF-7 human breast carcinoma cells. This mAb specifically detected glycolipids with the Y determinant Fuc alpha 1----2Gal beta 1----4GlcNAc(3----1 alpha Fuc)-beta 1----3Gal beta 1----4Glc beta 1----1 Cer and the Y-related B-active difucosylated determinant Gal alpha 1----3Gal(2----1 alpha Fuc) beta 1----4GlcNAc(3----1 alpha Fuc) beta 1----3Gal beta 1----4Glc beta 1----1 Cer, but was not reactive with related monofucosylated glycolipids of type 2 chain (X-antigen, blood group H), type 1 chain (Lea antigen, blood group H and B) or with difucosylated type 2 and type 1 chain structures (A blood group antigen or blood group B and Leb, respectively). A series of glycolipids with Y and blood group B type 2 determinants were detected in human gastric adenocarcinoma cell line KATO III with mAb BR55-2 and with a previously characterized anti-blood group B mAb PA83-52 (Hansson, G. C., Karlsson, K.-A., Larson, G., McKibbin, J. M., Blaszczyk, M., Herlyn, M., Steplewski, Z., and Koprowski, H. (1983) J. Biol. Chem. 258, 4091-4097). The isolated antigens were structurally characterized by mass spectrometry of permethylated and permethylated-reduced derivatives and by proton NMR spectroscopy. In a chromatogram binding assay, mAb BR55-2 and mAb PA83-52 detected minor components with slower mobility than the Y-6 and blood group B-7-type 2 structures. The detection of a B type 2 determinant is the first chemical evidence for the presence of an autologous difucosyl blood group B type 2 antigen in human adenocarcinoma cells.

ABO Blood-Group System↗
PubMed1989

Relationships between structure and biological activity of the mycolic acid-containing glycolipids from Nocardia asteroides "sensu stricto" and related species.

To reveal the taxonomical situation of Nocardia asteroides "sensu stricto", we compared the mycolic acid and mycolic acid-containing glycolipid composition and their granulomagenic activities in mice. The major glycolipids were glucose mono- and dimycolate, trehalose mono- and dimycolate and several unknown glycolipids, commonly, although the relative amount differed from strain to strains. On the other hand, molecular species composition of mycolic acids differed distinctively among the three closely related species: N. asteroides "sensu strico", N. farcinica and N. nova. GC/MS analysis showed the most abundant species of mycolic acids were C50(52) in N. asteroides, C54(52) in N. farcinica and C58(56) in N. nova, respectively with a different alpha-alkyl branch. Glucose mycolate and trehalose dimycolate possessing C50 mycolic acid showed a strong activity for granuloma formation in mice.

Animals↗
PubMed1988

Effect of the dietary alpha-linolenate/linoleate balance on lipid compositions and learning ability of rats. II. Discrimination process, extinction process, and glycolipid compositions.

Donryu strain rats through two generations were fed semi-purified diets supplemented with safflower seed oil (rich in linoleic acid) or with perilla seed oil (rich in alpha-linolenic acid), or a conventional laboratory chow (normal control diet). Brightness-discrimination learning ability was determined to be the highest in the perilla oil-fed group, followed by the normal group, and then by the safflower group, extending our earlier observation in a different strain of rat that alpha-linolenic acid is a factor in maintaining high learning ability (Yamamoto, N., M. Saitoh, A. Moriuchi, M. Nomura, and H. Okuyama. 1987. J. Lipid Res. 28: 144-151). After the brightness-discrimination learning test was administered, extinction of learning was measured. The time required for extinction was significantly longer in the safflower group than in either the perilla group or the normal diet group. Thus, the dietary alpha-linolenate/linoleate balance affected both the learning and the extinction of learning. The glycolipids of the cerebrum, cerebellum, and olfactory lobe were analyzed. Although the fatty acid compositions of the sulfatide and gangliosides were significantly different in the three parts of the brain, relatively little difference was observed in the fatty acids of glycolipids between the safflower group and the perilla group, suggesting that gross changes in brain glycolipids are not responsible for the differences in learning abilities between these dietary groups.

Animals↗
PubMed1988

Islet beta-cytotoxic monoclonal antibody against glycolipids in experimental diabetes induced by low dose streptozotocin and Freund's adjuvant.

Diabetes was induced in BALB/c mice by four injections of a subdiabetogenic dose (40 mg/kg) of streptozotocin in combination with CFA. The treatment increased the plasma glucose from 5.8 +/- 0.1 to 22.1 +/- 1.3 mmol/liter (n = 9). The diabetic animals had circulating islet cell surface antibodies (75%), and a monoclonal islet cell surface IgM antibody, K56aF3, generated from one of the diabetic BALB/c mice, mediated C-Dependent cytotoxicity against insulin-producing cells and inhibited glucose-stimulated insulin release from isolated rat islets. Solid phase assay on thin layer chromatograms showed no binding of the K56aF3 antibody to glycolipids prepared from relevant cells. However, testing against a series of glycolipids of various non-pancreatic origins showed a preferential binding to a nine-sugar glycolipid isolated from human erythrocytes carrying an unusual blood group A determinant (type 3). It is suggested that this mAb may be associated with the development of diabetes following a combination of polyclonal activation and non-diabetogenic doses of streptozotocin.

Animals↗
PubMed1987

Low serum antimycobacterial glycolipid antibody titers in the sera of patients with systemic lupus erythematosus associated with central nervous system involvement.

Antibodies which bind to glycolipids derived from Mycobacterium tuberculosis were sought in the sera of patients with systemic lupus erythematosus (SLE), with and without neurological disease, patients with active tuberculosis and normal controls. A significantly lower activity against the mycobacterial glycolipids was detected in the sera of patients with SLE with neurological involvement compared to other patients with SLE or controls. We suggest that low antibody levels against mycobacterial glycolipids may be useful in the diagnosis of patients with SLE in whom involvement of the central nervous system is suspected.

Antibodies, Bacterial↗
PubMed1988

[Protective activity of preparations of blood plasma from donors with a high titer of natural antibodies to Re-glycolipid of gram-negative bacteria].

The screening of the preparations of blood plasma obtained from 1,608 donors made it possible to establish the presence of high titers of natural antibodies to Re-glycolipid in 3% of the donors. Donor plasma containing antibodies to Re-glycolipid in a titer of 1:128 ensured a high level of protection for mice in experimental fecal peritonitis. The treatment of 10 patients having commonly occurring forms of peritonitis, caused by Gram-negative bacteria, with the use of such plasma yielded a positive clinical effect. The presence of correlation between the titers of antibodies to Re-glycolipid in blood plasma preparations and the content of high-density lipoproteids, expressed in per cent, was noted.

Adolescent↗
PubMed1988

Characterization of a nonspecific activator protein for the enzymatic hydrolysis of glycolipids.

We have studied the substrate specificities of a non-specific activator protein on the enzymatic hydrolyses of the following compounds: GM1 and GM2, as well as several of their derivatives including oligosaccharides, GgOse3Cer-II3-sulfate and LacCer-II3-sulfate, Gb-Ose3Cer and GbOse4Cer, three neolacto-series glycosphingolipids, and two non-ceramide glycolipids. Our results show that this activator protein has a broad spectrum of activity and exhibits the properties of a nonspecific natural detergent. The evidence of non-specificity was the ability of this activator protein to stimulate the hydrolyses of glycolipids, regardless of glycosphingolipids or non-ceramide glycolipids, carried out by glycosidases from animals, plants, and microorganisms. Its activity was, however, limited to substrates that had a lipid moiety. The oligosaccharide of GM1 and deacetyl-fatty acid free GM1 (II3-NeuGg-Ose4-sphingosine) were hydrolyzed by beta-galactosidase in the absence of this activator protein.

Enzyme Activation↗
PubMed1988

Glycolipids of rat glomerular mesangial cells: antibody against the cells reacts specifically to isoglobotetraosylceramide.

Cultured rat glomerular mesangial cells had relatively simple glycolipid composition which comprised mainly monoglycosylceramide, diglycosylceramide, isoglobotetraosylceramide and GM3. Beside these glycolipids, sulfatide, polar gangliosides and an unknown neutral glycolipid were detected in whole kidney and tubules. Polyclonal antibody against the cultured rat mesangial cells, which induced glomerular injury in vivo, bound specifically with isoglobotetraosylceramide.

Animals↗