UNIPROT:P43026 - FACTA Search

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

The magnesium salt of R-form lipopolysaccharide (LPS) from Klebsiella pneumoniae strain LEN-111 (O3-:K1-) that was prepared after the removal of cationic materials by electrodialysis formed essentially the same ordered hexagonal lattice structure with a lattice constant of 14 to 15 nm as the original non-electrodialyzed preparation of the R-form LPS. When the magnesium salt was suspended in 50 mM glycine buffer or Tris buffer at pH 1.4 to 9.5 and kept at 4 C for 24 hr, its content of Mg was markedly decreased, and its hexagonal lattice structure was changed to a swollen hexagonal lattice structure with extended lattice constants at pH 1.4 and to a loose mesh-like structure at pH 3.0 or higher. In the original non-electrodialyzed preparation of the R-form LPS, the release of Mg and disintegration of the hexagonal lattice structure did not occur by suspending in buffers at pH 1.4 to 8.5 at 4 C for 24 hr, but occurred only at pH 9.0 or higher. The results suggest that organic cations that can be removed by electrodialysis play some part in tight binding to Mg2+ and in stabilizing the ordered hexagonal assembly of the R-form LPS.
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PMID:Hexagonal assembly of the magnesium salt of an R-form lipopolysaccharide from Klebsiella pneumoniae: its lowered stability compared with original non-electrodialyzed preparation. 1088 59

Mercuric ion (Hg(2+)), one of the strongest thiol-binding agents known, mediates the toxicity associated with elemental, inorganic, and organic mercurial compounds. Studies of cellular events associated with Hg(2+) toxicity have focused largely on disruption of cell membranes and impairment of mitochondrial functions. In contrast, few studies have sought to define the specific molecular mechanisms through which Hg(2+) might affect toxicity via alteration of thiol-dependent signal transduction pathways that regulate cell proliferation and survival. Of particular interest in this regard is the effect of Hg(2+) on nuclear factor-kappaB (NF-kappaB), a pleiotropic transcriptional factor that is known to require reduced cysteine moieties at critical steps of activation and DNA binding. Here, we evaluated the effects of Hg(2+) on the expression of NF-kappaB in normal rat kidney epithelial (NRK52E) cells, a principal target of Hg(2+) toxicity. The lipopolysaccharide (LPS)-inducible form of NF-kappaB was readily detected in kidney cells and has been characterized as the p50p65 heterodimer. NF-kappaB-DNA binding was prevented in a dose-related manner by Hg(2+) (0-55 microM) in vitro when added to DNA binding reactions containing the nonthiol reducing agent Tris(2-carboxyethyl)phosphine hydrochloride (TCEP). Similarly, Hg(2+) at the same concentrations prevented DNA binding of a human recombinant wild-type p50p50 homodimer in binding reactions, and this effect was attenuated using a mutant form of the p50 protein containing a cys(62)-->ser(62) mutation. The inhibition of p50-DNA binding by Hg(2+) was reversible in a dose-related manner in vitro by competitive thiols DTT, GSH, and l-cysteine in binding reactions. In contrast, competitive thiols added to nuclear binding reactions were unable to reverse attenuation of LPS-mediated NF-kappaB-DNA binding affinity when cells were pretreated in vivo with Hg(2+) at concentrations as low as 2 microM prior to LPS administration. Immunoblot analyses indicted that Hg(2+) pretreatment of kidney cells substantially diminished, in a dose-related manner, the concentration of p65 translocated into the nucleus following LPS administration. Additionally, Hg(2+) pretreatment impaired both the phosphorylation and degradation of IkappaBalpha, suggesting a specific effect on NF-kappaB activation at the level of IkappaBalpha proteolysis. Finally, Hg(2+) at concentrations as low as 5 microM significantly diminished NF-kappaB-mediated transcriptional activity when administered to kidney cells transiently transfected with an NF-kappaB-driven luciferase reporter gene (pLuc-4xNF-kappaB) prior to LPS treatment. These findings demonstrate that Hg(2+), at low cellular concentrations, attenuates NF-kappaB activation at sites associated with IkappaBalpha phosphorylation and degradation, nuclear translocation of the p50p65 heterodimer, and association of p50-cys(62) with the DNA kappaB binding site. Attenuation of NF-kappaB activation by Hg(2+) through these mechanisms may underlie apoptotic or other cytotoxic responses that are known to be associated with low level Hg(2+) exposure in kidney epithelial cells.
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PMID:Mercuric ion attenuates nuclear factor-kappaB activation and DNA binding in normal rat kidney epithelial cells: implications for mercury-induced nephrotoxicity. 1143 39

Nitric oxide synthase (NOS) generates nitric oxide (NO*) by the oxidation of l-arginine. Spin trapping in combination with electron paramagnetic resonance (EPR) spectroscopy using ferro-chelates is considered one of the best methods to detect NO* in real time and at its site of generation. The spin trapping of NO* from isolated NOS I oxidation of L-arginine by ferro-N-dithiocarboxysarcosine (Fe(DTCS)2) and ferro-N-methyl-d-glucamide dithiocarbamate (Fe(MGD)2) in different buffers was investigated. We detected NO-Fe(DTCS)2, a nitrosyl complex, resulting from the reaction of NO* and Fe(DTCS)2, in phosphate buffer. However, Hepes and Tris buffers did not allow formation of NO-Fe(DTCS)2. Instead, both of these buffers reacted with Fe2+, generating sparingly soluble complexes in the absence of molecular oxygen. Fe(DTCS)2 and Fe(MGD)2 were found to inhibit, to a small degree, NOS I activity with a greater effect observed with Fe(MGD)2. In contrast, Fe(MGD)2 was more efficient at spin trapping NO* from the lipopolysaccharide-activated macrophage cell line RAW264.7 than was Fe(DTCS)2. Data suggested that Fe(DTCS)2 and Fe(MGD)2 are efficient at spin trapping NO* but their maximal efficiency may be affected by experimental conditions.
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PMID:Differential effect of buffer on the spin trapping of nitric oxide by iron chelates. 1167 94

Addition of tris(hydroxymethyl)-aminomethane (Tris) into the culture medium of Azospirillum brasilense sp245 changes the antigenic properties of the lipopolysaccharide (LPS) isolated from the external membrane of the bacteria. LPS preparations from the bacteria grown in the presence of Tris have been analyzed by immunodiffusion, using monospecific antibodies. The disappearance of the precipitation band corresponding to one of the two O-specific polysaccharides of the LPS (O-PS1) and changes in the electrophoretic profile have been revealed. However, only minor differences in absorption spectra of products of O-PS1 reaction with phenol/sulfuric acid have been demonstrated between the bacteria grown under standard conditions and in the presence of Tris.
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PMID:[Changes in the antigenic properties of Azospirillum brasilense lipopolysaccharide on addition of tris(hydroxymethyl)-aminomethane into the culture medium]. 1206 82

We tested the hypothesis that PGs mediate lipopolysaccharide (LPS)-induced behavioral fever in the toad Bufo paracnemis. Measurements of preferred body temperature (T(b)) were performed with a thermal gradient. Toads were injected intraperitoneally with the cyclooxygenase inhibitor indomethacin (5 mg/kg), which inhibits PG biosynthesis, or its vehicle (Tris) followed 30 min later by LPS (0.2 and 2 mg/kg) into the lymph sac. LPS at the dose of 0.2 mg/kg caused a significant increase in T(b) from 7 to 10 h after injection, and then T(b) returned toward baseline values. LPS at the dose of 2 mg/kg produced a different pattern of response, with a longer latency to the onset of fever (10th h) and a longer duration (until the end of the experiment at the 15th h). Tris significantly attenuated the fever induced by LPS at 0.2 mg/kg, but not at 2 mg/kg. Moreover, indomethacin completely blocked the fever evoked by LPS (2 mg/kg). These results indicate that the behavioral fever induced by LPS in toads requires the activation of the COX pathway, suggesting that the involvement of PG in fever has an ancient phylogenetic history and that endogenous PGs raise the thermoregulatory set point to produce fever, because behavioral thermoregulation seems to be related to changes in the thermoregulatory set point.
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PMID:Indomethacin impairs LPS-induced behavioral fever in toads. 1213 58

The outer membrane (OM) of the mammalian pathogen Leptospira kirschneri was isolated in the form of membrane vesicles by alkaline plasmolysis and separated from the protoplasmic cylinder by sucrose density gradient ultracentrifugation. All four components of the alkaline plasmolysis buffer, including 1.0 M NaCl, 27% sucrose (wt/vol), 2 mM EDTA, and 10 mM Tris (pH 9), were required for efficient OM release, as judged by recovery of leptospiral lipopolysaccharide. Two populations of OM vesicles (OMVs) were recovered, with peak concentrations found in the sucrose gradient at densities of 1.16 and 1.18 g/ml. Transmission electron microscopy revealed that the more buoyant OMV population was smaller (<0.1 micro m in diameter) than the denser OMV population (0.2 to 0.3 micro m in diameter). The densities of both populations of OMVs were distinct from that of the protoplasmic-cylinder material, which was found in the sucrose gradient at a density of 1.20 g/ml. The OMV fractions were free of protoplasmic-cylinder material, as judged by immunoblotting with antibodies to the endoflagellar sheath protein, heat shock protein GroEL, and two novel cytoplasmic membrane proteins, lipoprotein LipL31 and transmembrane protein ImpL63. The protein components of the OMVs were characterized by one- and two-dimensional immunoblotting and found to include previously described OM proteins (OMPs), including the porin OmpL1; the lipoproteins LipL32, LipL36, and LipL41; and the peripheral membrane protein P31(LipL45). A number of less well-characterized OMPs were also identified, including those with molecular masses of 16, 21, 21.5, 22, 31, 36, 44, 48, 90, and 116 kDa. The 48-kDa OMP was identified as a novel OM lipoprotein designated LipL48. The use of membrane-specific markers in OM isolation techniques facilitates an accurate description of the leptospiral OM and its components.
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PMID:Characterization of the leptospiral outer membrane and description of three novel leptospiral membrane proteins. 1218 39

The biosynthetically double-labeled lipopolysaccharide (LPS), containing (3)H-labeled on the fatty acyl-chains and (14)C-labeled on the glucosamine of Salmonella enterica serotype typhimurium, was isolated from bacteria grown in proteose peptone-beef extract (PPBE) medium in the presence of labeled precursors; 133 micro Ci/ml of [2-(3)H] acetate sodium salt and 0.167 micro Ci/ml of N-acetyl[D-1-(14)C]glucosamine. The LPS was extracted from the bacteria with 90% phenol/chloroform/petroleum ether, purified and stored in 0.1% (v/v) triethylamine/10 mM Tris HCl at -70 degrees C. Tissue slices and portions of the meninges were prepared and incubated in artificial cerebrospinal fluid (CSF) or Krebs phosphate buffer (Krebs) containing 150 ng/ml LPS with [(3)H] LPS (0.004 micro Ci/ml, sp. act. 28 micro Ci/mg LPS). The tissues were incubated under 95% oxygen/5% carbon dioxide at 37 degrees C with constant agitation until steady-state uptake was reached (60 min). At the end of the incubation period, tissues were processed for radioactivity measurement. The rat tissue partitioning of LPS in artificial CSF for brain and Krebs for other organs was measured by using the ratio of tissue to medium at the steady state in vitro. The following results were obtained from the study: Heart, 0.15; liver, 0.19; spleen, 0.12; kidney, 0.18; stomach, 0.17; small intestine, 0.18; brain stem, 0.10; cerebellum, 0.11; meninges, 0.77; hippocampus, 0.12; hypothalamus, 0.12; frontal cortex, 0.09 and caudate nucleus, 0.10. This information, along with plasma or blood/buffer partition coefficients, is a requisite for constructing a physiologically-based pharmacokinetic (PBPK) model of endotoxins for quantitative risk assessment.
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PMID:Determination of the rat tissue partitioning of endotoxin in vitro for physiologically-based pharmacokinetic (PBPK) modeling. 1521 10

Asbell, Mary A. (University of Georgia, Athens), and R. G. Eagon. Role of multivalent cations in the organization, structure, and assembly of the cell wall of Pseudomonas aeruginosa. J. Bacteriol. 92:380-387. 1966. -Incubation of Pseudomonas aeruginosa with ethylenediaminetetraacetate induced the formation of osmotically fragile rods termed osmoplasts. These could be restored to osmotically stable forms by multivalent cations. Only those cells restored by divalent cations normally found in the cell wall were capable of multiplication. The respiration of restored cells, however, was unimpaired, irrespective of whether they were capable of multiplication. Moreover, the permeability characteristics of osmoplasts and restored cells were unimpaired. When multivalent cations were chelated from the cell wall and replaced by sodium, a weakened cell wall and an osmotically fragile cell resulted. This was apparently caused by the absence of cross-linkages in the cell wall via multivalent cations. Tris(hydroxymethyl)aminomethane buffer compounded the lethal effects of ethylenediaminetetraacetate. The lipopolysaccharide component was inferred to be the site of attack by ethylenediaminetetraacetate. A mechanism for the synthesis of the lipopolysaccharide sacculus was proposed whereby negatively charged subunits are "trapped" by forming ionic and coordinate bonds intermediated by multivalent cations.
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PMID:Role of Multivalent Cations in the Organization, Structure, and Assembly of the Cell Wall of Pseudomonas aeruginosa. 1656 24

Anredera cordifolia (Ten.) Steenis, or the synonymous name of Boussingaultia baselloides or Boussingaultia gracilis var. pseudobaselloides, is a South American species of ornamental succulent vine, commonly known as the madeira-vine. The fresh leaves of madeira-vine are frequently used as vegetables. A. cordifolia is an evergreen climber that grows from fleshy rhizomes. The rhizome contained one major (23kDa) protein band under non-reducing condition in the SDS-PAGE. The first 15 amino acids in the N-terminal region of the major protein band (23kDa), named tentatively ancordin, were KDDLLVLDIGGNPVV which were highly homologous to sequences of winged bean seed protein ws-1, Medicago truncatula proteinase inhibitor, soybean trypsin inhibitor, and sporamin. By using activity stains, the ancordin showed trypsin inhibitory activity in the SDS-PAGE gel which was found not only in rhizomes but also in aerial tubers, but few in fresh leaves. The crude extracts from rhizomes of madeira-vine were directly loaded onto trypsin-Sepharose 4B affinity column. After washing with 100mM Tris-HCl buffer (pH 7.9) containing 100mM NaCl, the ancordin was eluted directly by 0.2M KC1-HC1 buffer (pH 2.0). In calculation, the purified protein exhibited 0.0428mug trypsin inhibition/mug ancordin (corresponding to 0.53 unit of TPCK-treated trypsin inhibited/mug ancordin). The purified ancordin was used to evaluate the nitric oxide productions in RAW264.7 cells in the presence of polymyxin B (poly B, 50microg/ml) to eliminate the lipopolysaccharide (LPS) contaminations. It was found that ancordin (1.25-5microg/ml) could dose-dependently (R=0.954) stimulate the nitric oxide (NO) productions (expressed as nitrite concentrations) in RAW264.7 cells without significant cytotoxicity, and kept the similar effects in NO production in 6.25microg/ml ancordin.
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PMID:Ancordin, the major rhizome protein of madeira-vine, with trypsin inhibitory and stimulatory activities in nitric oxide productions. 1749 81

Curcumin can reduce inflammation and neurodegeneration, but its chemical instability and metabolism raise concerns, including whether the more stable metabolite tetrahydrocurcumin (TC) may mediate efficacy. We examined the antioxidant, anti-inflammatory, or anti-amyloidogenic effects of dietary curcumin and TC, either administered chronically to aged Tg2576 APPsw mice or acutely to lipopolysaccharide (LPS)-injected wild-type mice. Despite dramatically higher drug plasma levels after TC compared with curcumin gavage, resulting brain levels of parent compounds were similar, correlating with reduction in LPS-stimulated inducible nitric-oxide synthase, nitrotyrosine, F2 isoprostanes, and carbonyls. In both the acute (LPS) and chronic inflammation (Tg2576), TC and curcumin similarly reduced interleukin-1beta. Despite these similarities, only curcumin was effective in reducing amyloid plaque burden, insoluble beta-amyloid peptide (Abeta), and carbonyls. TC had no impact on plaques or insoluble Abeta, but both reduced Tris-buffered saline-soluble Abeta and phospho-c-Jun NH(2)-terminal kinase (JNK). Curcumin but not TC prevented Abeta aggregation. The TC metabolite was detected in brain and plasma from mice chronically fed the parent compound. These data indicate that the dienone bridge present in curcumin, but not in TC, is necessary to reduce plaque deposition and protein oxidation in an Alzheimer's model. Nevertheless, TC did reduce neuroinflammation and soluble Abeta, effects that may be attributable to limiting JNK-mediated transcription. Because of its favorable safety profile and the involvement of misfolded proteins, oxidative damage, and inflammation in multiple chronic degenerative diseases, these data relating curcumin dosing to the blood and tissue levels required for efficacy should help translation efforts from multiple successful preclinical models.
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PMID:Curcumin structure-function, bioavailability, and efficacy in models of neuroinflammation and Alzheimer's disease. 1841 33

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