Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P43026 (lipopolysaccharide)
 62,215 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Immunoglobulin-producing Merwin plasma cells, MPC-11, have been found to contain proplyl hydroxylase (prolyl-glycyl-peptide,2-oxoglutarate:oxygen oxidoreductase; EC 1.14.11.2) activity and its crossreacting protein, as well as hydroxyproline and a collagenous protein that could not be classified as type I, II, or III collagen. Friend leukemic cells, on the other hand, contained only prolyl hydroxylase. Thymus-derived (T) lymphocytes and bone-marrow-derived (B) lymphocytes freshly isolated from BALB/c mice expressed low but significant prolyl hydroxylase activity. Upon stimulation with phytohemagglutinin, the enzyme activity in T cells increased 22- to 29-fold. Crossreacting protein was also increased and appeared more stable than the prolyl hydroxylase. The effect of lipopolysaccharide stimulation on B cells uas similar but not as pronounced. Thus, even when not accompanied by other collagen biosynthetic activities, prolyl hydroxylase is present in all cells of hematologic origin.
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PMID:Expression of collagen biosynthetic activities in lymphocytic cells. 20 96

Indoleamine 2,3-dioxygenase [indoleamine: oxygen 2,3-oxidoreductase (decyclizing)] activity in the supernatant fraction (30,000 X g, 30 min) of the mice lung homogenate increased approximately 30- to 50-fold after an intraperitoneal administration of bacterial lipopolysaccharide. In all other tissues tested, no significant increase in enzyme activity was observed. The effect appeared to be specific for the lipopolysaccharide fraction because glycogen and zymosan were almost ineffective under the same experimental conditions. In the lung, the enzyme activity increased almost linearly during the first 24 hr after a single injection of the lipopolysaccharide fraction (20 microgram per mouse). The enzyme activity started to decrease after 48 hr and reached a normal value after about 6 days. The increase in enzyme activity was completely abolished by cycloheximide or actinomycin D. Other enzymes in the lung such as beta-glucuronidase, acid phosphatase, and monoamine oxidase did not change significantly with this treatment.
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PMID:Induction of pulmonary indoleamine 2,3-dioxygenase by intraperitoneal injection of bacterial lipopolysaccharide. 27 15

Although nitric oxide (.N = O) biosynthesis is inducible in rat hepatocytes (HC), the physiological significance of .N = O production by these cells is unknown. Short exposure of HC to authentic .N = O led to a concentration-dependent inhibition of mitochondrial aconitase, NADH-ubiquinone oxidoreductase, and succinate-ubiquinone oxidoreductase (complexes I and II of the mitochondrial electron transport chain). Most susceptible to .N = O inhibition was mitochondrial aconitase, in which a reduction in enzyme activity to 20.2 +/- 1.6% of control was observed. In contrast to mitochondrial aconitase, cytosolic aconitase activity was not inhibited by .N = O. After exposure to a maximal inhibitory concentration of .N = O, mitochondrial aconitase activity recovered completely within 6 h. Complex I did not fully recover within this incubation period. Endogenous .N = O biosynthesis was induced in HC by a specific combination of cytokines and lipopolysaccharide. After 18 h of incubation with these stimuli, a significant inhibition of mitochondrial aconitase activity to 70.8 +/- 2.4% of controls was detected. However, this was due only in part to the action of .N = O. A non- .N = O-dependent inhibition of mitochondrial function appeared to be mediated by tumor necrosis factor.
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PMID:Effect of exogenous and endogenous nitric oxide on mitochondrial respiration of rat hepatocytes. 190 97

Administration of purified bacterial lipopolysaccharide (LPS) to male rats suppressed the constitutive hepatic expression of the male-specific cytochrome P-450 [AH, reduced flavoprotein:oxygen oxidoreductase (RH hydroxylating), E.C.1.14.14.1] isozyme P-450h (P450IIC11) to about 35% of control levels within 24 hr. The mRNA for P-450h was more rapidly and more profoundly suppressed than was the protein, indicating (a) that the decrease in the mRNA was responsible for the suppression of the protein and (b) that other mechanisms work to maintain expression of P-450h apoprotein in the face of repression of its mRNA. Suppression of P-450h expression was maximal at an endotoxin dose of 30-100 micrograms/kg, indicating that P-450 suppression is concomitant with the acute-phase response of hepatic secretory proteins. The female-specific cytochrome P-450 isozyme, P-450i (P450IIC12), was suppressed to 17% of control levels by LPS administration in female rats. Suppression of the P-450i apoprotein by LPS, and recovery of its expression, was more rapid than was suppression of P-450h in males. P-450i protein and mRNA levels were concomitantly suppressed by LPS, indicating that although there is a pretranslational component to the suppression, other mechanisms may also contribute. Calculations based on estimations of the microsomal contents of P-450h and P-450i relative to the total cytochrome P-450 in untreated rat livers indicate that suppression of these forms contributes significantly to the decreases in total microsomal P-450 after LPS treatment. In these studies, hepatic microsomal NADPH-cytochrome c reductase (TPNH2-cytochrome c reductase, E.C.1.6.2.4) activities and content of cytochrome b5 were decreased by LPS administration in both male and female rats. Like its effects on cytochrome P-450 expression, endotoxin suppression of NADPH-cytochrome c reductase activities and cytochrome b5 levels was more rapid in female rats than in males. The production of a local inflammatory response in male rats by subcutaneous injection of turpentine caused effects on cytochrome P-450, P-450h expression, and cytochrome b5 that were similar to those of endotoxin but were less rapidly achieved.
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PMID:Suppression of constitutive cytochrome P-450 gene expression in livers of rats undergoing an acute phase response to endotoxin. 251 27

The incorporation of rhamnose and glucose into the core part of the lipopolysaccharide (LPS) of Pseudomonas aeruginosa was studied using enzyme preparations from strain PAC1R and LPS-defective mutants derived from it. Crude membrane preparations from the LPS-defective mutant PAC556 transferred rhamnose from dTDP-L-[14C]rhamnose to material insoluble in trichloracetic acid. The preparations contained both transferase enzyme and acceptor, the former being destroyed by heating. Between 60 and 70% of the radioactive rhamnose transferred to the membranes was extractable by aqueous phenol and non-diffusible. The material extracted did not move in any of the chromatography solvents tested and contained rhamnose as the sole radioactive component. Soluble dTDP-L-rhamnose-LPS rhamnosyltransferase was obtained from the parent strain PAC1R by ammonium sulphate precipitation of a 105000 g supernatant fraction from broken bacteria. It was most active at pH 8 with 5 mM-MgCl2 and required heat-treated membranes of PAC556 as acceptor. This mutant, whose LPS lacks both O-antigenic side-chains and rhamnose in the core, was shown to lack either the epimerase or the NADP-dependent oxidoreductase used to synthesize dTDPrhamnose. After preincubation with soluble transferase and UDPglucose, heated membranes of mutant strains PAC611, PAC612 and PAC605 could also act as acceptors for rhamnose. These mutants all lacked some or all of the glucose as well as the rhamnose from the core of their LPS and the experiments thus provided confirmation that rhamnose was the terminal hexose of the core in P. aeruginosa PAC1.
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PMID:Biosynthesis of the core part of the lipopolysaccharide of Pseudomonas aeruginosa. 677 64

Nitric oxide (NO) produces rapid osteoclast detachment and contraction in vitro, and this effect is accompanied by a profound inhibition of bone resorption. Work by others has confirmed these findings in vivo: inhibition of NO synthase [NOS; L-arginine, NADPH: oxygen oxidoreductase (NO-forming), EC 1.14.13.39] in normal rats is followed by increased bone resorption reflected by a marked loss in bone mineral density. In our present study, immunocytochemistry and Northern blotting show the presence of the constitutive calcium-sensitive NOS isoform (cNOS) in normal rat osteoclasts and in the human preosteoclast cell line (FLG 29.1). The inducible NOS isoform (iNOS) was also clearly demonstrable in the rat cells especially after treatment with gamma interferon (IFN-gamma) and bacterial wall products [lipopolysaccharide (LPS)], while a basal level of transcript was detected in the untreated human preosteoclast line. However NADPH-diaphorase activity was intense only in neonatal rat osteoclasts attached to bone, perhaps reflecting either enhancement of cNOS activity by calcium or increased amounts of the inducible isoform in activated osteoclasts in situ compared with isolated neonatal rat osteoclasts. These actively resorb devitalized bone but the untreated cells contain relatively low levels of NOS; they are extremely sensitive to inhibition by NO. The iNOS inhibitor aminoguanidine markedly enhances in vitro resorption by activated NOS-rich chick osteoclasts and by normal rat osteoclasts treated with LPS or IFN-gamma. In contrast, the nonselective NOS inhibitor NG-monomethyl-L-arginine inhibits resorption by untreated neonatal rat osteoclasts. Thus, osteoclast function may require intermittent calcium-stimulated increases in NO production by cNOS against a basal inhibitory background activity of the iNOS isoform. However, bone resorption depends on precursor replication and on the activity of the mature cells, and we found that the NO donor 3-morpholinosydnonimine (SIN-1) (50 microM) profoundly depressed replication in the human preosteoclast line. Taken together, these results strongly suggest that NO maintains a central control of bone resorption in both avian and mammalian species by exerting a powerful tonic restraint of osteoclast numbers and activity. The presence of NOS in human cells implies a similar function in man and that conventional views of calcium homoeostasis and skeletal metabolism will need substantial revision. Since NO also influences behavior of the osteoblast, the bone-forming cell, in vitro, a similar effect in vivo might imply a general influence on bone remodeling.
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PMID:Bidirectional regulation of osteoclast function by nitric oxide synthase isoforms. 753 33

The melanization reaction, which is a common response to parasite entry in invertebrate animals, especially arthropods, is due to the activity of an oxidoreductase, phenoloxidase. This enzyme is part of a complex system of proteinases, pattern recognition proteins and proteinase inhibitors constituting the so-called prophenoloxidase-activating system. It is proposed to be a non-self recognition system because conversion of prophenoloxidase to active enzyme can be brought about by minuscule amounts of molecules such as lipopolysaccharide, peptidoglycan and beta-1, 3-glucans from micro-organisms. Several components of this system recently have been isolated and their structure determined.
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PMID:Role of the prophenoloxidase-activating system in invertebrate immunity. 952 6

The purpose of this study was to determine if exacerbation of apoptosis precedes liver injury during chronic exposure of rats to alcohol. After 7 weeks of feeding an alcohol- or dextrin-containing liquid diet, the animals were treated with gram-negative bacterial lipopolysaccharide (1 mg x kg(-1) body weight, intravenously) or sterile saline and sacrificed 3 hr after the treatment. Alanine:2-oxoglutarate aminotransferase (ALT) and lactate:NAD oxidoreductase [lactate dehydrogenase (LDH)] were measured in plasma. The caudate lobe of the liver was resected for histology, while the rest of the organ was perfused with collagenase to isolate hepatocytes, Kupffer cells (KCs), and sinusoidal endothelial cells (SECs) by centrifugal elutriation. Hepatocyte mitochondria were isolated by differential centrifugation of the cell homogenate. Reduced and oxidized glutathione (GSH and GSSG) in isolated hepatocytes and hepatocyte mitochondria, and malondialdehyde in hepatocytes were assayed. Caspase-3 activity and Fas ligand mRNA expression were determined in hepatocytes, KCs, and SECs. Plasma ALT and LDH activity, liver histology, GSH, GSSG and their ratio, and malondialdehyde content were not affected by alcohol treatment Caspase-3 activity was significantly increased in alcohol-treated rats in all three cell types, with the lowest response observed in hepatocytes and the highest in KCs. Fas ligand mRNA expression, which had the highest level in SECs, followed by KCs and hepatocytes, was not affected by alcohol administration. Lipopolysaccharide had the following effects: an increase in ALT in both pair- and alcohol-fed rats, and LDH only in alcohol-fed rats, a decrease in GSH + GSSG levels in both mitochondria and hepatocytes, an elevation of malondialdehyde content in hepatocytes, a raise in caspase-3 activity in all groups and cell types, and an augmentation of Fas ligand expression in hepatocytes and KCs, but not in SECs. These data suggest that, during chronic alcohol consumption, an exacerbated apoptosis precedes alcohol-induced liver injury.
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PMID:Modulation of caspase-3 activity and Fas ligand mRNA expression in rat liver cells in vivo by alcohol and lipopolysaccharide. 1006 67

The enzyme CDP-D-glucose 4,6-dehydratase (EC 4.2.1.45) is an NAD(+)-dependent oxidoreductase which catalyzes the irreversible conversion of CDP-D-glucose to CDP-4-keto-6-deoxy-D-glucose. The product of this reaction is an intermediate in the synthesis of all CDP-linked 3,6-dideoxyhexoses, an important class of antigenic determinants found in the lipopolysaccharide layer of Gram-negative bacteria. Crystals of a recombinant form of this enzyme from Yersinia pseudotuberculosis have been grown in two crystal forms, both possessing pseudo-translational non-crystallographic symmetry, with dramatically different diffraction characteristics. A complete 1.8 A data set has been collected from the primitive orthorhombic crystal form, for which the non-crystallographic symmetry is described in detail.
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PMID:Purification, crystallization and molecular symmetry of CDP-D-glucose 4,6-dehydratase from Yersinia pseudotuberculosis. 1180 80

Macrophage migration inhibitory factor (MIF) is a pro-inflammatory mediator with the ability to induce various immunomodulatory responses and override glucocorticoid-driven immunosuppression. Some of these functions have been linked to the unusual enzymatic properties of the protein, namely tautomerase and oxidoreductase activities. However, there are conflicting reports regarding the functional role of these enzymatic properties in normal physiological homeostasis and disease progression. Therefore, we have produced a highly pure, virtually endotoxin-free recombinant MIF preparation and fully characterized this using a variety of biochemical and biophysical approaches. The recombinant protein, with demonstrable enzymatic activity, was then used to systematically examine the biological activity of MIF. Surprisingly, treatment with MIF alone failed to induce cytokine expression, with the exception of IL-8. However, co-treatment of lipopolysaccharide (LPS) in conjunction with MIF produced synergistic secretion of tumor necrosis factor-alpha, interleukin (IL)-1, and IL-8 compared with LPS alone. The potentiating effect of MIF was seen at physiologically relevant concentrations. These data suggest that MIF has no conventional cytokine activity but, rather, acts to modulate and amplify the response to LPS.
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PMID:Human macrophage migration inhibitory factor: a proven immunomodulatory cytokine? 1689 95


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