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Query: UNIPROT:P43026 (lipopolysaccharide)
 62,215 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Isolation of lipid A by acid hydrolysis of Shigella flexneri lipopolysaccharide resulted in a product that consisted of a heterogeneous mixture of bands when visualized by thin layer chromatography. Differential extraction with ethyl acetate and chloroform, or extraction with EDTA, followed by chloroform-methanol-water (Bligh-Dyer extraction), or a combination of both extraction schemes, resulted in partial purification of immunologically active lipid A. Eight fractions were purified further by preparative thin layer chromatography, and each of the fractions had phosphate, carbohydrate, and esterified fatty acids. Upon incorporation into liposomes, five of the eight purified fractions reacted with anti-lipid A serum, but the three fractions with the most number of esterified fatty acids failed to react with anti-lipid A serum. At least one fraction that originally was unreactive with anti-lipid A serum became reactive as a hapten inhibitor upon removal of esterified fatty acids by alkaline hydrolysis. Alkali-treated fractions from "unreactive" and "reactive" lipid A had similar activities as hapten inhibitors. Our data suggest that lipid A can exist in multiple forms that differ by the number and placement, and possibly by the type, of fatty acids linked to the carbohydrate of lipid A. Highly acylated forms of lipid A do not react with antiserum against the unpurified lipid A mixture, but removal of fatty acids does expose immunoreactive groups.
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PMID:Lipid A from endotoxin: antigenic activities of purified fractions in liposomes. 11 18

1. The lipid fraction extracted from the outer and cytoplasmic membranes of Proteus mirabilis with chloroform/methanol consisted almost entirely of phosphatidylethanolamine, diphosphatidylglycerol and phosphatidylglycerol. 2. The phospholipid content of the cytoplasmic membrane was more than twice that of the outer membrane (38% as against 18% of the total dry weight) and the proportions of the three phospholipids differed somewhat in the two membranes. Yet, the fatty acid composition of the extractable lipids was essentially the same in both membranes. 3. The freedom of motion of spin-labeled fatty acids in the outer membrane of P. mirabilis depended markedly on temperature and on the position of the nitroxide group on the hydrocarbon chain of the probe, suggesting that the local environment of the probe is an associate lipid structure with the properties of a bilayer. Nevertheless, the mobility of the probe was more restricted in the outer membrane than in the cytoplasmic membrane, indicating a higher viscosity of the outer membrane. 4. Chloroform/methanol completely removed the phospholipids from the outer membrane, leaving the lipopolysaccharide moiety intact. The motion of spin-labeled fatty acids in the extracted membranes was, however, highly restricted, suggesting that, in the native outer membrane, the local environment of the probe is composed of phospholipids rather than lipopolysaccharide. Aqueous acetone extraction removed only 75-80% of the phospholipids of the outer membrane. Nevertheless, the mobility of the spin-labeled fatty acid remained highly restricted, suggesting the existence of two phospholipid environments in the outer membrane differing in the nature of their association with the lipopolysaccharide and protein moieties.
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PMID:The outer membrane of Proteus mirabilis. II. The extractable lipid fraction and electron-paramagnetic resonance analysis of the outer and cytoplasmic membranes. 16 15

Heat-stable enterotoxin (ST) produced by porcine strains of enterotoxigenic (ENT+) Escherichia coli has been purified to apparent homogeneity by sequential ultrafiltration, acetone fractionation, preparative gel electrophoresis, diethylaminoethyl Bio-Gel A ion-exchange chromatography, and Bio-Gel P-10 gel filtration. The enterotoxin, purified more than 1,500-fold, exhibited a molecular weight of 4,400, as determined by both sodium dodecyl sulfate-gel electrophoresis and gel filtration. A molecular weight of 5,100, representing 47 residues, was calculated from amino acid analysis data. The amino acid content was distinctive, with an unusually high proportion of cystines and few hydrophobic amino acids. A single amino-terminal residue, glycine, was observed. Purified ST was stable to heating (100 degrees C, 30 min) and did not lose biological activity after treatment with Pronase, trypsin, proteinase K, deoxyribonuclease, ribonuclease, and phospholipase C. Periodic acid oxidation and several organic solvents (acetone, phenol, chloroform, and methanol) had no effect on the biological activity of ST. Further, purified ST was stable to acid treatment at pH 1.0 but lost biological activity at pH values greater than 9.0. Neither lipopolysaccharide nor lipid contamination was evident in purified preparations. A characteristic absorption spectrum was observed during the course of the purification, which shifted from a maximum at 260 nm in crude preparations to 270 nm for the purified toxin. Antiserum obtained from rabbits immunized with ST or ST coupled to bovine serum albumin neutralized the action of the enterotoxin in suckling mice; however, passive hemagglutination and hemolysis titer assays suggested that ST is a poor antigen.
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PMID:Purification and chemical characterization of the heat-stable enterotoxin produced by porcine strains of enterotoxigenic Escherichia coli. 34 81

The effect of treatment with the methanol extraction residue (MER) mycobacterial fraction on the immunological responsiveness of BALB/c mice to the T-independent antigens pneumococcal polysaccharide type III (SIIII) and trinitrophenyl-lipopolysaccharide conjugate (TNP-LPS) was ascertained. Pretreatment with MER prevented the establishment of immunological paralysis by threshold doses (10 or 15 microgram) of SIII and by a paralyzing dose of 100 microgram TNP-LPS. The induction of immunological paralysis by SIII was unaffected by treatment with the bacterial adjuvant Corynebacterium parvum and with the B cell mitogens PPD, LPS (Escherichia coli lipopolysaccharide), and dextran sulfate.
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PMID:Effect of the MER tubercle bacillus fraction on the responsiveness of mice to T-independent antigens. 37 26

Bacterial lipopolysaccharides extracted from Bacteroides fragilis subspecies fragilis lacked 2-keto-3-deoxyoctonate and heptose, sugars which make up part of the inner core of most bacterial endotoxins. Over 98% of the lipid portion of this material could be removed easily with chloroform-methanol and alcohol, a finding which indicates a loose association between the polysaccharide and lipid moieties. The lipopolysaccharides caused gelation of limulus lysate at a concentration significantly higher than that for the endotoxin of Salmonella typhi. None of the extracts was lethal in 10-day-old chick embryos at doses of greater than 200 mug per egg, whereas the endotoxin of Neisseria meningitidis was lethal at a dose of 1.2 mug per egg. The local Shwartzman reaction could not be induced by levels of B. fragilis endotoxin of up to 1,000 mug per rabbit, whereas a (control) endotoxin of S. typhi induced this phenomenon at a level of 3 mug per rabbit. Intact oxygen-killed B. fragilis failed to provoke the local Shwartzman reaction at doses of 2,500 mug. These results indicate that B. fragilis has a lipopolysaccharide different from that of most gram-negative bacteria. Although it retains some of the chemical and biologic properties of classical endotoxin, it seems to lack others. This observation may have significant clinical implications.
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PMID:Chemical and biological characterization of the lipopolysaccharide of Bacteroides fragilis subspecies fragilis. 93 22

The stimulation of guinea pig lymphocytes by phytohemagglutinin (PHA), concanavalin A (ConA), methanol-extracted residues of tubercle bacilli (MER), purified protein derivative of tubercle bacilli (PPD), dextran sulphate (DS) and E. coli lipopolysaccharide (LPS), was determined and compared with that of mouse lymphoid cells. The sources of lymphocytes tested were spleen, thymus, lymph nodes and bone marrow. The degree of activation of DNA synthesis by PHA and ConA was higher in guinea pig thymocytes and lymph node cells than in corresponding sources of mouse lymphocytes. The optimum degree of stimulation by PHA and ConA was approximately the same in guinea pig thymocytes, while ConA was by far a better stimulator than PHA for mouse thymocytes. All four B-cell mitogens tested (MER, DS, PPD and LPS) activated DNA synthesis in mouse lymphoid cells while only MER and DS were effective in guinea pig lymphocytes. A guinea pig spleen cell population depleted from B cells was not stimulated, neither by DS nor by MER, while it still responded to PHA and ConA. These results indicate that the proliferative response due to MER and DS occurs in the B-cell compartment. It is suggested that the differences between guinea pigs and mice with respect to their ability to develop a cell-mediated type immunity and to respond to T-independent antigens are related to differences in the relative proportions and degrees of maturation of T- and B-cell subpopulations, as reflected by the selective responsiveness to various mitogens.
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PMID:Differences between lymphoid cell populations of guinea pigs and mice as determined by the response to mitogens in vitro. 108 31

The O-specific polysaccharide was obtained by mild degradation of the Salmonella arizonae O61 lipopolysaccharide with acid. It contained 2-acetamido-2-deoxy-D-glucose, 2-acetamidino-2,6-dideoxy-L-galactose (FucAm), and 7-acetamido-3,5,7,9-tetradeoxy-5-[(R)-3-hydroxybutyramido]-D- glycero-L-galacto-nonulosonic acid (Sug). On the basis of partial acid hydrolysis with 0.1 M HCl, solvolysis with anhydrous HF in methanol, and 1H- and 13C-NMR analysis (including 1H/13C inversely correlated spectroscopy for localisation of N-acyl substituents), it was concluded that the O-specific polysaccharide had the following structure. ----3)-alpha-L-FucAm-(1----3)-alpha-D-GlcNAc-(1----8)-beta-Sug+ ++-(2---- The O-antigen of S. arizonae O61 is structurally related to that of Pseudomonas aeruginosa O12, thus explaining the known serological cross-reactivity between these micro-organisms.
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PMID:The structure of the O-specific polysaccharide chain of the lipopolysaccharide of Salmonella arizonae O61. 139 6

Surface labeling of chlamydial elementary and reticulate bodies in L929 cells infected with Chlamydia trachomatis serotype L2 was monitored by using monoclonal antibodies (MAb) against the major outer membrane protein and lipopolysaccharide (LPS). Different staining and fixation procedures were used to detect these surface antigens during the developmental cycle. Anti-major outer membrane protein MAb yielded a clear staining pattern of exclusively chlamydial inclusions independent of the fixation or staining technique used. Anti-LPS MAb gave a faint staining pattern of reticulate bodies when methanol fixation was used and showed that LPS was released from chlamydiae into the host cell cytoplasm and into the surroundings of the infected host cell. However, when paraformaldehyde-glutardialdehyde fixation was used, extracellular LPS staining was not observed. The data show that chlamydial LPS is loosely bound in the bacterial outer membrane but suggest that shedding of LPS is a fixation artifact.
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PMID:Staining of surface antigens of Chlamydia trachomatis L2 in tissue culture. 139 57

The aim of this study was to investigate the antigenic structures of the morphologically distinct cells of the Coxiella burnetii developmental cycle. Postembedding immunoelectron microscopy with polyclonal antibodies produced in rabbits to (i) phase I cells, (ii) a chloroform-methanol residue fraction of cells, (iii) the cell walls (CW) of large and small cells and small dense cells (SDC), and (iv) the peptidoglycan-protein complexes of small cells and SDC labelled the continuum of morphologically distinct cells. But these antibodies did not distinguish between the antigenic structures of the various cells. Monoclonal antibodies to the phase I lipopolysaccharide labelled the CW of a majority of the smaller cells, but there was diminished reactivity to the larger cells. Although monoclonal antibodies to a 29.5-kDa outer membrane protein labelled the CW of the large mother cells, the large cells, and the small cells, a minority of the SDC with compact CW were not labelled. The endogenous spore within the mother cell was not labelled by the polyclonal or monoclonal antibodies to cellular components. A selected population of SDC was prepared by osmotic lysis of large cells, differential centrifugation, Renografin step-gradient fractionation, and breakage of the small cells in a French press at 20,000 lb/in2. The pressure-resistant SDC collected as fraction CL did not contain the 29.5-kDa protein, as evidenced by the lack of (i) Coomassie brilliant blue staining of protein in the 29.5-kDa region of sodium dodecyl sulfate-polyacrylamide gels and (ii) reactivity of the 29.5-kDa protein antigenic epitopes in immunoblotting with monoclonal antibodies to the protein. In contrast, CW of the pressure-sensitive small cells contained the 29.5-kDa protein. Therefore, the observed ultrastructural differences between large and small cells and SDC reflect differences in sensitivity to breakage by pressure treatment and in cell-associated antigens. Although the process of differentiation in C. burnetii remains an enigma, we have taken steps toward identifying cellular antigens as markers of differentiation. The pressure-resistant SDC in fraction CL that are devoid of the 29.5-kDa protein may be useful for answering questions about the physiological events required for triggering outgrowth and sequential regulation of the Coxiella developmental cycle.
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PMID:Antigenic differences between Coxiella burnetii cells revealed by postembedding immunoelectron microscopy and immunoblotting. 171 26

Mycoplasmas (M. gallisepticum, chicken mycoplasmas), in concert with interferon gamma (IFN gamma), were effective in activating macrophages (M theta) to be tumoricidal. The M theta-activating capacity of mycoplasmas was maintained after treatment with heat. 0.1 M NaOH, 1 M HCl, or trypsin. M theta-activating factor was extracted from mycoplasmas with chloroform/methanol and water (Mf-B). Mf-B was also effective in activating M theta in the presence of IFN gamma. The threshold dose of Mf-B for M theta of ordinary C3H/He mice and that for those of C3H/HeJ mice, the latter being known to be low responders to bacterial lipopolysaccharide, were actually the same. This seems to indicate that the effectiveness of Mf-B was not attributable to possibly contaminating lipopolysaccharides, and that the pathway of activity of Mf-B is different from that of lipopolysaccharides. Since the M theta-activating principle was only a very small part of Mf-B, we have not yet succeeded in identifying it, but there was no evidence that it was protein, nucleic acid, sugar, or lipid. The cytotoxicity of M theta activated by Mf-B plus IFN gamma was dependent on L-arginine in the culture, suggesting that arginine metabolites are involved in M theta cytotoxicity. Mf-B induced a small amount of tumor necrosis factor in M theta, and this induction was markedly enhanced by IFN gamma.
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PMID:Macrophage-activating factor extracted from mycoplasmas. 190 96


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