Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: EC:3.1.4.3 (phospholipase C)
18,461 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The conditions necessary for the secretion of phospholipase C (phosphatidylcholine cholinephosphohydrolase) by Pseudomonas aeruginosa were studied. Enzyme secretion by washed cell suspensions required a carbon source and ammonium, potassium, and calcium ions. The calcium requirement could be substituted by magnesium and strontium but not by copper, manganese, cobalt, or zinc. During growth in liquid medium, cells secreted phospholipase C during late logarithmic and early stationary phases. Secretion was repressed by the addition of inorganic phosphate but not by organic phosphates, glucose, or sodium succinate. Studies with tetracycline indicated that de novo protein synthesis was necessary for the secretion of phospholipase C and that the exoenzyme was not released from a preformed periplasmic pool. Similarly, extraction of actively secreting cells with 0.2 M MgCl2 at pH 8.4 solubilized large quantities of the periplasmic enzyme alkaline phosphatase but insignificant amounts of phospholipase C. Bacteria continued to secrete enzyme for nearly 45 min after the addition of inorganic phosphate or rifampin.
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PMID:Secretion of phospholipase C by Pseudomonas aeruginosa. 11 87

The adenosine diphosphate ribosyl transferase activity of Pseudomonas aeruginosa exotoxin A(PA toxin) was found to be rapidly destroyed by heating at 45 to 60C but not by heating at 70 to 90C (for at least 30 min). This phenomenon has been previously described for other bacterial toxins (staphylococcal alpha-toxin and Vibrio parahaemolyticus hemolysin) and is termed an Arrhenius effect. In contrast, the Arrhenius effect was not seen when the PA toxin was heat-treated as above and tested for cell toxicity or mouse lethality. Although the PA toxin treated at 70C for 30 min retained a significant proportion (is greater than 70%) of its adenosine diphosphate ribosyl transferase activity, the cell toxicity and mouse lethality of the toxin were virtually abolished. A temperature-dependent inactivating factor that has proteolytic activity and is co-purified with the PA toxin was shown to be responsible for the Arrhenius effect. PA toxin separated from the factor by conventional disc gel electrophoresis or PA toxin preparations lacking the factor did not show the Arrhenius effect.
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PMID:Temperature-dependent inactivating factor of Pseudomonas aeruginosa exotoxin A. 17 6

Substrate specificities of phospholipases C[EC 3.1.4.3] from Clostridium novyi, Clostridium perfringens, Bacillus cereus, and Pseudomonas aureofaciens were studied under the same conditions. Phospholipases C from Clostridium novyi and Bacillus cereus show wide substrate specificities while those of Clostridium perfringens and Pseudomonas aureofaciens show relatively narrow specificities. On the basis of these results, the hydrolytic actions of these phospholipases on membrane lipids of Escherichia coli, Bacillus cereus, and Clostridium novyi were examined under the same conditions. The enzymes of Clostridium novyi and Bacillus cereus attacked all the membranes and their lipid extracts, hydrolyzing phosphatidylethanolamine, phosphatidylglycerol, lyso-phosphatidylethanolamine, and o-aminoacylphosphatidylglycerol. Phospholipase C from Pseudomonas aureofaciens attacked these three membranes and their lipid extracts, hydrolyzing phosphatidylethanolamine. Phospholipase C from Clostridium perfringens hardly attacked the phospholipids of these bacterial membranes. However, phospholipase C from Clostridium perfringens hydrolyzed phosphatidylethanolamine in a mixture containing lipid extract from Escherichia coli membrane and purified phosphatidylcholine from egg yolk.
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PMID:Hydrolytic action of phospholipases on bacterial membranes. 20 10

Phospholipase C (phosphatidylcholine cholinephosphohydrolase, EC 3.1.4.3) from Pseudomonas aureofaciens was purified 3600-fold from the culture filtrate with a recovery of 1.6%. Purification was performed with the useof (NH4)2SO4 precipitation, Sephadex G-100 gel filtration and by ion-exchange chromatography on DEAE-Sephadex A-50 and CM-Sephadex C-50. The purified enzyme appeared to be homogeneous as revealed by polyacrylamide disc gel electrophoresis at pH 9.3. The molecular weight was estimated to be 35 000 by gel filtration on Sephadex G-75. Under our experimental conditions, phosphatidylethanolamine was more rapidly hydrolysed than phosphatidylcholine. Lyso forms of these two phosphatides were poor substrates. Phosphatidylserine, phosphatidylglycerol, phosphatidylinositol, cardiolipin and sphingomyelin were not hydrolysed. The enzyme activity with phosphatidylcholine as substrate was slightly stimulated by Ca2+, Mg2+, and Mn2+. However, these cations inhibited the activity with phosphatidylethanolamine as substrate. An anionic detergent, sodium deoxycholate, slightly enhanced the activity when phosphatidylcholine and phosphatidylethanolamine were used as substrates. A cationic detergent, cetyltrimethylammonium bromide, inhibited enzyme activity. EDTA and o-henanthroline inhibited the activity of the enzyme to a marked degree.
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PMID:Studies on phospholipase C from Pseudomonas aureofaciens. I. Purification and some properties of phospholipase C. 24 4

Binding of 125I-labeled human chorionic gonadotropin to Pseudomonas maltophilia is dependent on time, temperature, and pH and the binding to this procaryotic species is hormone-specific and saturable. The equilibrium dissociation constant is 2.3 X 10(-9) M. There are no cooperative interactions between binding sites (Hill coefficient, 1.05). The number of sites is estimaated as 240 fmol/100 mug of protein. NaCl and KCl, at concentrations from 1 to 10 mM, have no effect on binding. Divalent cations (Mg2+ and Ca2+) and 1 mM EDTA inhibit hormone binding. Binding is destroyed by heat or by treatment with Pronase of alpha-chymotrypsin and is increased by phospholipase C. Binding of the labeled gonadotropin is not observed with other gram-negative organisms--e.g., Escherichia coli, Pseudomonas testosteroni, Pseudomonas aeruginosa, Enterobacter aerogenes, or Enterobacter cloacae.
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PMID:Specific gonadotropin binding to Pseudomonas maltophilia. 26 83

A new colorimetric determination for serum phospholipid is described. Firstly, serum phospholipid is incubated with phospholipase C from Bacillus cereus, and then the released diglyceride and triglyceride are hydrolyzed completely to fatty acid and glycerol by lipoprotein lipase from Pseudomonas fluorescens. Secondly, the glycerol produced is enzymatically determined by glycerol dehydrogenase in the presence of NAD+, using phenazine methosulfate-nitro blue tetrazolium as color reagents. The absorbance at 570 nm is recorded. The amount of the glycerol from phospholipid is calculated by subtracting the amount of glycerol from triglyceride from the amount of total glycerol. The present method requires only 20 microliter of serum and a 40 min incubation and is highly reproducible. The results obtained show good correlation with those obtained by a chemical method (correlation coefficient, 0.925) or the phospholipase D-choline oxidase method (correlation coefficient, 0.936). These results strongly suggest that the proposed method can be utilized as a routine clinical test.
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PMID:An enzymic determination for serum phospholipid. 70 86

Phospholipase C [EC 3.1.4.3] from Pseudomonas aureofaciens was found to be inhibited by chelating reagents such as ethylenediaminetetraacetate [EDTA] and o-phenanthroline. The inhibition was reversed by the addition of Zn2+ and, to a lesser extent, by Co2+ and Mn2+. On isoelectric focusing, the isoelectric point of this enzyme proved to be 6.3--6.5, with a single peak. The enzyme reaction with the substrate was followed in media containing an organic solvent such as diethyl ether or diethyl ether-ethyl alcohol. When ethyl alcohol was added (up to 2%) to the reaction mixture in ether, there were no marked changes in the hydrolytic rates of phosphatidylcholine and phosphatidylethanolamine. However, the enzyme activity was inhibited when the alcohol concentration was increased above 2%. In 98% diethyl ether-2% ethyl alcohol, phosphatidylcholine was hydrolyzed more rapidly than phosphatidylethanolamine, in contrast with the result obtained in water. In the single micelle state, phosphatidylethanolamine was hydrolyzed more rapidly than phosphatidylcholine or lysophatidylcholine. Acidic phospholipids and sphinogomyelin were not hydrolyzed. When the enzyme was incubated with phospholipid mixture extracted from Ps aureofaciens and rat liver, both phosphatidylethanolamine and phosphatidylcholine were hydrolyzed more rapidly than in the single micelle state of these substrates.
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PMID:Studies on phospholipase C from Pseudomonas aureofaciens. II. Further studies on the properties of the enzyme. 82 22

We evaluated several potential effects of erythromycin (EM) on host defense systems and the virulence of Pseudomonas aeruginosa. Peritoneal macrophages obtained from mice given 250 mg of EM per kg of body weight for 7 days by the intraperitoneal, intravenous, subcutaneous, or oral route produced significantly greater amounts of thymocyte-activating factors. These data suggest that EM enhances the in vivo production of cytokines, such as interleukins 1 and 6. Treatment of P. aeruginosa D4 with subinhibitory concentrations of EM enhanced the association of bacteria with murine Kupffer cells in vitro and increased bacterial clearance from the blood in mice. EM suppressed the in vitro production of exotoxin A, total protease, elastase, and phospholipase C by P. aeruginosa D4; exotoxin A production by P. aeruginosa PA-103; and total protease production by P. aeruginosa B16 and PAO1 in a generally dose-dependent manner. These data demonstrate that EM produces various effects in addition to its direct antimicrobial activity, suggesting that it has potential as an immunomodulator or bacterial virulence-suppressing agent against P. aeruginosa and other infections.
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PMID:Potential effects of erythromycin on host defense systems and virulence of Pseudomonas aeruginosa. 141 82

In Pseudomonas aeruginosa, the effect of different cations on the acid phosphatase activity was studied in order to acquire more information related to a previously proposed mechanism, involving the coordinated action of this enzyme with phospholipase C. Although the natural substrate of this enzyme is phosphorylcholine, in order to avoid the possible interaction of its positive charge and those of the different cations with the enzyme molecule, the artificial substrate p-nitrophenylphosphate was utilized. Kinetic studies of the activation of acid phosphatase (phosphorylcholine phosphatase) mediated by divalent cations Mg2+, Zn2+ and Cu2+ revealed that all these ions bind to the enzyme in a compulsory order (ordered bireactant system). The Km values obtained for p-NPP in the presence of Mg2+, Zn2+ and Cu2+ were 1.4 mM, 1.0 mM and 3.5 mM, respectively. The KA values for the same ions were 1.25 mM, 0.05 mM and 0.03 mM, respectively. The Vmax obtained in the presence of Cu2+ was about twofold higher than that obtained in the presence of Mg2+ or Zn2+. The inhibition observed with Al3+ seems to be a multi-site inhibition. The K'app and n values, from the Hill plot, were about 0.25 mM and 4.0 mM, respectively, which were independent of the metal ion utilized as activator. It is proposed that the acid phosphatase may exert its action under physiological conditions, depending on the availability of either one of these metal ions.
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PMID:Pseudomonas aeruginosa acid phosphatase. Activation by divalent cations and inhibition by aluminium ion. 154 81

Pseudomonas aeruginosa produces phospholipase C (PLC), a heat-labile hemolysin. Histopathological analysis of PLC-treated mice revealed that the primary target organs involved in PLC-induced toxicity were the liver and kidney. Mice treated i.v. with PLC demonstrated significant tubular epithelial necrosis of the kidney with hematuria, while when given i.p. they exhibited hepatonecrosis with cellular infiltration. Splenomegaly was also a consistent finding. Results from in vitro studies indicate that PLC is toxic for mouse peritoneal cells and human leukocytes.
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PMID:In vivo and in vitro toxicity of phospholipase C from Pseudomonas aeruginosa. 155 86


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