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At least 883 records · Page 49Linked to original sources
PubMed1986

Decay accelerating factor of complement is anchored to cells by a C-terminal glycolipid.

Membrane-associated decay accelerating factor (DAF) of human erythrocytes (Ehu) was analyzed for a C-terminal glycolipid anchoring structure. Automated amino acid analysis of DAF following reductive radiomethylation revealed ethanolamine and glucosamine residues in proportions identical with those present in the Ehu acetylcholinesterase (AChE) anchor. Cleavage of radiomethylated 70-kilodalton (kDa) DAF with papain released the labeled ethanolamine and glucosamine and generated 61- and 55-kDa DAF products that retained all labeled Lys and labeled N-terminal Asp. Incubation of intact Ehu with phosphatidylinositol-specific phospholipase C (PI-PLC), which cleaves the anchors in trypanosome membrane form variant surface glycoproteins (mfVSGs) and murine thymocyte Thy-1 antigen, released 15% of the cell-associated DAF antigen. The released 67-kDa PI-PLC DAF derivative retained its ability to decay the classical C3 convertase C4b2a but was unable to membrane-incorporate and displayed physicochemical properties similar to urine DAF, a hydrophilic DAF form that can be isolated from urine. Nitrous acid deamination cleavage of Ehu DAF at glucosamine following labeling with the lipophilic photoreagent 3-(trifluoromethyl)-3-(m-[125I]iodophenyl)diazirine ([125I]TID) released the [125I]TID label in a parallel fashion as from [125I]TID-labeled AChE. Biosynthetic labeling of HeLa cells with [3H]ethanolamine resulted in rapid 3H incorporation into both 48-kDa pro-DAF and 72-kDa mature epithelial cell DAF. Our findings indicate that DAF and AChE are anchored in Ehu by the same or a similar glycolipid structure and that, like VSGs, this structure is incorporated into DAF early in DAF biosynthesis prior to processing of pro-DAF in the Golgi.

CD55 Antigens↗
PubMed1987

Estrogen influences dolichyl phosphate distribution among glycolipid pools in mouse uteri.

The steroid hormone 17 beta-estradiol dramatically induces uterine N-linked glycoprotein assembly [Dutt, A., Tang, J.-P., Welply, J. K., & Carson, D. D. (1986) Endocrinology (Baltimore) 118, 661-673]. To determine the role that dolichyl phosphate availability plays in this induction, we studied the effects of estrogen priming on the content of dolichyl phosphate and the distribution of dolichyl phosphate among various glycolipids in uteri. Dolichol-linked saccharides were metabolically labeled to equilibrium with either [3H]glucosamine or [3H]mannose and extracted from primary explants of uterine tissue. The amount of dolichol-linked saccharide was calculated from the specific radioactivity determined for the corresponding sugar nucleotides extracted from the tissues. The major dolichol-linked saccharides identified were mannosylphosphoryldolichol (MPD), oligosaccharylpyrophosphoryldolichol (OSL), and N,N'-diacetylchitobiosylpyrophosphoryldolichol (CBL). Estrogen increased the levels of MPD and OSL 4-fold; however, CBL levels did not change. After 3 days of treatment, the levels of these glycolipids were very similar to those in uteri from pregnant mice. Remarkably, MPD constituted 90-95% of dolichol-linked saccharides detected under all conditions. The tissue contents of total dolichyl phosphate and alkali-labile dolichyl phosphate, presumably MPD, were estimated by liquid chromatography. The levels of alkali-labile dolichyl phosphate determined in this way were in good agreement with the values estimated for MPD by metabolic labeling; moreover, alkali-labile dolichyl phosphate constituted 50-98% of the total dolichyl phosphate pool. The variations in MPD content depended upon the steroid hormone influence, most notably that of estrogen.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1990

Mycobacteria glycolipids as potential pathogenicity effectors: alteration of model and natural membranes.

Four mycobacterial wall glycolipids were tested for their effects on phospholipidic liposome organization and passive permeability and on oxidative phosphorylation of isolated mitochondria. From fluorescence polarization of diphenylhexatriene performed on liposomes it was concluded that the two trehalose derivatives (dimycoloyltrehalose and polyphthienoyltrehalose) rigidified the fluid state of liposomes, the triglycosyl phenolphthiocerol slightly fluidized the gel state, while the peptidoglycolipid ("apolar" mycoside C) just shifted the phase transition temperature upward. Dimycoloyltrehalose was without effect on liposome passive permeability, as estimated from dicarboxyfluorescein leak rates, and polyphthienoyltrehalose and triglycosyl phenolphthiocerol slightly decreased leaks, while mycoside C dramatically increased leaks. Activity of these lipids on mitochondrial oxidative phosphorylation was examined. The two trehalose derivatives have been tested previously: both had the same type of inhibitory activity, dimycoloyltrehalose being the most active. Triglycosyl phenolphthiocerol was inactive. Mycoside C was very active, with effects resembling those of classical uncouplers: this suggested that its activity on mitochondria was related to its effect on permeability. All these membrane alterations were called nonspecific because it is likely that they result from nonspecific lipid-lipid interactions, and not from recognition between specific molecular structures. Such nonspecific interactions could be at the origin of some of the effects of mycobacteria glycolipids on cells of the immune system observed in the last few years.

Animals↗
PubMed1975

Characterization by mass spectrometry of blood group A active glycolipids from human and dog small intestins.

Glycolipids with blood group A activity isolated from human and dog small intestine have been characterized by mass spectrometry of intact lipid in methylated and in methylated and reduced (LiAiH4) form. Without degradative studies the glycolipids were conclusively shown to be hexaglycosyleramides with phytosphingosine as the major long-chain base and hydroxypalmitic acid as the major fatty acid. The exact sugar ratio was hexose-hexosamine-deoxyhexose 3:2:1 and the sequence established as hexosamine-[deoxyhexose-]hexose-hexosamine-hexose-hexose-ceramide. Evidence is presented that mass spectrometry can differential between type ) and type 2 saccharide chains.

ABO Blood-Group System↗
PubMed1996

Characterization of two glycolipid: alpha 2-3sialyltransferases, SAT-3 (CMP-NeuAc:nLcOse4Cer alpha 2-3sialyltransferase) and SAT-4 (CMP-NeuAc:GgOse4Cer alpha 2-3sialyltransferase), from human colon carcinoma (Colo 205) cell line.

Sialyltransferase activities, SAT-3 (CMP-NeuAc:nLcOse4Cer alpha 2-3sialyltransferase) and SAT-4 (CMP-NeuAc:GgOse4Cer alpha 2-3sialyltransferase), in Colo 205 cells catalyze the transfer of sialic acid to the terminal galactose of GlcNc-- and GalNAc-containing glycolipid substrates, respectively. Competition kinetic studies with nLcOse4Cer and GM1 as substrates in a sialyltransferase assay show that these two activities are catalyzed by two different catalytic entities. The two enzymes were co-solubilized with taurochlorate and resolved by DEAE--Cibacron Blue--Sepharose column chromatography into two elution peaks. The column eluent with SAT-3 activity failed to transfer sialic acid to asialo alpha(1)-acid glycoprotein, indicating that this enzyme is different from the sialyltransferase (ST3N) that synthesizes NeuAc alpha 2-3Gal linkage in asparagine-linked oligosaccharides of glycoprotein. However, SAT-3 activity can be immunoprecipitated with a polyclonal antibody produced against a protein expressed in Escherichia coli as GST-fusion protein from an ECB cDNA homolog of an alpha 2-3 sialyltransferase SAT-3 or STZ) the has been cloned from human melanoma cell and human placenta. Thus a concentration-dependent decrease in the residual SAT-3 activity relative to SAT-4 activity was observed in the supernatant after precipitation of the immune complex. Expression of SAT-3 (STZ) cDNA was also detected in Colo 205 cell by RT-PCR, followed by sequence analysis of the RT-PCR product. Characterization of the catalytic reaction products of SAT-3 and SAT-4 with thin-layer chromatography, sialidase treatment, and binding to specific antibodies indicates that both SAT-3 and SAT-4 catalyze the formation of alpha 2-3 linkage between sialic acid and terminal galactose of glycolipid substrates.

Base Sequence↗
PubMed2004

Synthesis and supramolecular assemblies of bipolar archaeal glycolipid analogues containing a cis-1,3-disubstituted cyclopentane ring.

Unsymmetrical archaeal tetraether glycolipid analogues 1-2 incorporating a 1,3-disubstituted cyclopentane ring into the bridging chain have been synthesized. The cyclopentane has been introduced with a totally controlled cis configuration, either into the middle of the aliphatic chain or at three methylene groups from the glycerol unit linked to the bulkier disaccharide residue. Freeze-fracture and cryotransmission electron microscopy experiments clearly demonstrated unprecedented glycolipid supramolecular organizations involving two-by-two monolayer associations coupled with interconnection and fusion phenomena. Furthermore, a significant difference in the hydration properties and in the lyotropic liquid crystalline behavior of bipolar lipids 1-2 was found depending on the position of the cyclopentane residue.

Archaea↗
PubMed2001

Analysis of molecular species of glycolipids in fruit pastes of red bell pepper (Capsicum annuum L.) by high-performance liquid chromatography-mass spectrometry.

Five major glycolipid classes (acylated steryl glucoside, steryl glucoside, monogalactosyldiacylglycerol, digalactosyldiacylglycerol, and glucocerebroside) from fruit pastes of red bell pepper were separated by silica gel column chromatography. The molecular species of each glycolipid were separated and characterized by reversed-phase high-performance liquid chromatography coupled with on-line mass spectrometry using atmospheric pressure chemical ionization. The molecular species of steryl glucoside were beta-sitosteryl and campesteryl glucosides, and those of the acylated steryl glucoside were their fatty acid esters. The dilinolenoyl species was predominant in monogalactosyldiacylglycerol in addition to small amounts of another five molecular species, whereas digalactosyldiacylglycerol consisted of seven molecular species varying in their degree of unsaturation. The glucocerebroside class contained at least seven molecular species, which were characterized by proton nuclear magnetic resonance spectroscopy.

Capsicum↗
PubMed1999

Analyses of glycolipids from fish, shellfish, and sea snake lipids by high-performance liquid chromatography.

To determine the existence of glycolipids (neutral glycosphingolipid and glycoglycerolipid) in sea snake, round frigate mackerel, sardine, sea urchin, and abalone, we performed silica gel chromatography and high-performance liquid chromatography (HPLC) using an Aquasil-SS column and a C(8)-reversed phase silica gel column. HPLC with a UV absorption detector was used to analyze neutral glycosphingolipid. These chromatograms showed typical peaks in round frigate mackerel lipid, in sea snake crude fat, in abalone intestine lipid, and in sea urchin intestine lipid. UV-HPLC was also used to analyze glycoglycerolipid. These chromatograms indicated a large peak in round frigate mackerel lipid and a small peak in purified sardine oil. In addition, we observed the same peaks in the glycolipid fraction of round frigate mackerel muscle lipids and sea snake crude fat using a differential refractometer detector. The results of this study suggest that the peaks are neutral glycosphingolipid or glycoglycerolipid and that neutral glycosphingolipid and glycoglycerolipid may have specific physiological functions in each living creature.

Animals↗
PubMed1990

Glycolipids as host resistance stimulators.

6-(5-Cholesten-3 beta-yloxy)hexyl 1-thio-beta-D-mannopyranoside (L-644,257) enhances natural host resistance in cyclophosphamide-treated mice against Pseudomonas aeruginosa in a dose-dependent manner. It is active sc, im, and ip but not orally. L-644,257 is substantially more protective against P. aeruginosa than its alpha anomer. The beta-L-fucose glycolipid is more effective when given im and ip than sc. The lactose and beta-D-glucose glycolipids were only marginally effective to nonprotective. The 17 beta-steroidal side chain of L-644,257 can be modified without substantial loss of protective activity.

Adjuvants, Immunologic↗
PubMed2006

Synthesis and self-assembling properties of diacetylene-containing glycolipids.

Diacetylene-containing glycolipids are interesting molecules that have many potential applications. The polydiacetylenes formed by the cross-linking of the diacetylene lipids are new stimuli-responsive materials. In particular, diacetylene lipids that can form gels in aqueous solution are of great interest in designing functional biocompatible materials. We have synthesized a series of diacetylene-containing sugar lipids with different chain lengths, substituents, and positions of diyne and studied their self-assembling properties in several solvents including hexane, ethanol, and ethanol/water mixture. Among the 24 diacetylene-containing glycolipids synthesized, many of them exhibited excellent gelation properties in ethanol or ethanol/water mixture. Typically very long chain diacetylene lipids formed gels in ethanol and hexane. Shorter chain diacetylene lipids and compounds with one free hydroxyl group can form gels in aqueous solution. The position of the diyne and chain length affect the self-assembling properties significantly. The systematic study of the gelation properties for diacetylene lipids with different lipid chains can help us to understand the structure requirement for the desired physical properties. Optical microscopy studies showed that the molecules form interesting architectures such as tubules, rods, sheets, and belts. The resulting organogels can also be cross-linked and give different colored polymerized gels depending on their structures.

Acetylene↗
PubMed2005

Size effect of polydiacetylene vesicles functionalized with glycolipids on their colorimetric detection ability.

In this paper, the size effect of the polydiacetylene vesicles functionalized with glycolipids on their colorimetric detection ability has been studied. Polydiacetylene vesicles in which were incorporated glycolipids acted as a model system for the affinochromatic property. Visible color changes from blue to red could be observed to the naked eye owing to Con A binding to the sugar moiety and be detected quantitatively by the visible absorption spectrum. In the experiment, small and uniform vesicles were obtained after extrusion through membranes with different pore sizes. The morphology and mean size distribution of the extruded vesicles were studied by transmission electron microscopy (TEM) and dynamic light scattering (DLS), respectively. Our work shows that the smaller the vesicles are, the stronger is the effect, making the detection of Con A easier. The results may apply to the sensitivity enhancement of polydiacetylene biosensors for the recognition of other biomolecules.

Colorimetry↗
PubMed2005

Vesicular catalysis of an S(N)2 reaction: toward understanding the influence of glycolipids on reactions proceeding at the interface of biological membranes.

The kinetics of the S(N)2 reaction of a series of aromatic alkylsulfonates with water and bromide ions in membrane mimetic media have been investigated. These media include vesicles formed from only synthetic amphiphiles, vesicles composed only of phospholipids and mixtures of these components. Special focus is placed on the influence of the addition of n-dodecyl-beta-glucoside as a mimic for glycolipids. The kinetic data have been analyzed by using the pseudophase model for bimolecular reactions. Contrary to previous results on a base-catalyzed E2 reaction (Org. Biomol. Chem. 2004, 2, 1789-1799), the presence of n-dodecyl-beta-glucoside at the vesicular surface does not lead to large rate accelerations for the S(N)2 reaction. In fact, when present at 50 mol % (i.e., the additive covers 34% of the vesicular surface) these glycolipid mimics appear not to affect the bimolecular rate constants, but they only decrease the local water concentration by about 40%. The reactivity of water at the surface of vesicles that are formed from cationic amphiphiles appears to be increased about 10-fold relative to the reactivity of water in the bulk liquid, whereas in zwitterionic vesicles the reactivity is comparable to that in bulk water. The obtained rate constants are also compared to micellar rate constants.

Bromides↗
PubMed1999

A novel cytokine-inducing glycolipid isolated from the lipoteichoic acid fraction of Enterococcus hirae ATCC 9790: a fundamental structure of the hydrophilic part.

Previously, we showed that quantitatively minor several glycolipids totaling only less than 5% of the lipoteichoic acid (LTA) fraction from Enterococcus hirae ATCC 9790 possessed cytokine-inducing activity, whereas the major component (over 90%) did not [Suda et al. (1995) FEMS Immun Med Microbiol 12:97-112]. The major inactive component was shown to have the chemical structure as was proposed for the LTA by Fischer [Hashimoto et al. (1997) J Biochem 121:779-86], suggesting that so-called LTA is not a cytokine-inducing component in the Gram-positive bacteria. In the present paper, the structure of the hydrophilic part of one of the cytokine-inducing glycolipid tentatively named GL4 is elucidated. GL4 was first subjected to hydrolysis with aqueous HF to give a polysaccharide and a mixture of low molecular weight products. The polysaccharide was composed mainly of highly branching mannan as concluded from NMR and MS analyses of its acetolysis products. The low molecular weight products consisted of phosphate and glycerol, suggesting the presence of a poly(glycerophosphate) structure in the original GL4. From these observations, the hydrophilic part of GL4 was shown to consist of mannose-rich polysaccharide and poly(glycerophosphate), the latter being bound to the former by a phosphodiester linkage.

Carbohydrate Sequence↗
PubMed2001

A synthetic glycolipid prevents autoimmune encephalomyelitis by inducing TH2 bias of natural killer T cells.

Experimental autoimmune encephalomyelitis (EAE) is a prototype autoimmune disease mediated by type 1 helper T (TH1) cells and under the control of regulatory cells. Here we report that a synthetic glycolipid ligand for CD1d-restricted natural killer T (NKT) cells expressing the semi-invariant T-cell receptor (Valpha14+) is preventive against EAE. The ligand is an analogue of alpha-galactosylceramide (alpha-GC), a prototype NKT cell ligand, with a truncated sphingosine chain. alpha-GC causes NKT cells to produce both interferon (IFN)-gamma and interleukin (IL)-4 (refs 4, 5). However, this new ligand can induce a predominant production of IL-4 by the NKT cells. A single injection of this glycolipid, but not of alpha-GC, consistently induced TH2 bias of autoimmune T cells by causing NKT cells to produce IL-4, leading to suppression of EAE. The lack of polymorphism of CD1d and cross-reactive response of mouse and human NKT cells to the same ligand indicates that targeting NKT cells with this ligand may be an attractive means for intervening in human autoimmune diseases such as multiple sclerosis.

Amino Acid Sequence↗
PubMed2006

Glycolipids for natural killer T cells.

Natural killer T cells (NKT cells) play a central role in regulating immune responses influencing conditions ranging from autoimmune to infectious diseases. NKT cell responses are induced by recognition of glycolipid antigens presented by CD1d, an antigen presentation protein. In the last 10 years great strides have been made in understanding the types of glycolipids recognized by NKT cells. These advances have included determination of the lipid and carbohydrate recognition requirements for stimulation and identification of "natural" antigens for these cells.

Adjuvants, Immunologic↗
PubMed1968

The glycolipids of Lactobacillus casei A.T.C.C. 7469.

1. The lipids were extracted from Lactobacillus casei A.T.C.C. 7469 with chloroform-methanol mixtures. The glycolipids were obtained by chromatography on silicic acid and DEAE-cellulose (acetate form). 2. Hydrolysis of the glycolipids with alkali gave two glycerol glycosides and a mixture of fatty acids. 3. The glycosides were separated and their structures elucidated. The major component was O-alpha-d-galactopyranosyl-(1-->2)-O-alpha-d-glucopyranosyl-(1-->1)-glycerol and the minor component O-alpha-d-glucopyranosyl-(1-->6)-O-alpha-d-galactopyranosyl-(1-->2)-O-alpha-d-glucopyranosyl-(1-->1)-glycerol. 4. Analysis of the fatty acids by gas-liquid chromatography showed that they were predominantly palmitic acid, octadecenoic acid and lactobacillic acid.

Chloroform↗
PubMed1971

Occurrence of long-chain fatty acids and glycolipids in the cell envelope fractions of baker's yeast.

1. The total yield of fatty acids from the whole envelopes was markedly higher than that obtained from the ordinary cell walls. In both samples the major fatty acids were C(16) and C(18) acids. 2. The whole envelopes contained C(18) acids and long-chain (C(19)-C(26)) fatty acids, in a higher proportion than did the ordinary cell walls. Fifteen fatty acids with more than 18 carbon atoms were identified, among which 2-hydroxy-C(26:0) and C(26:0) acids predominated. 3. A complex sphingolipid containing inositol, phosphorus and mannose was isolated from the whole cell envelopes. The main fatty acids of this lipid were 2-hydroxy-C(26:0) and C(26:0) acids. It was concluded that this sphingolipid is present both in the ordinary cell wall and in the plasma membrane of baker's yeast. 4. The neutral lipids amounted to over 50% and the glycerophosphatides to about 30% of the total fatty acid content of the whole envelope. The major fatty acids in these lipids were C(16:1), C(18:1) and C(16:0) acids. The proportion of fatty acids with more than 18 carbon atoms was lowest in the neutral lipids, whereas the neutral glycolipids contained the highest percentage of these fatty acids. Acidic glycolipids amounted to 14% of the total fatty acid content of the whole envelope. The presence of a cerebroside sulphate in this lipid fraction was demonstrated, whereas the high content of 2-hydroxy-C(26:0) acid found is caused by the complex inositol- and mannose-containing sphingolipid.

Cell Fractionation↗