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)

A study was made of 111 strains of plasma-negative spathylococci isolated from the blood, pleural fluid, urine, and exudate of the abdominal cavity of 30 patients. The studies were carried out by 18 criteria. A variety of biological properties and signs characteristic of pathogenic staphylococci (hemolytic activity, anaerobic splitting of mannite, the presence of phosphatase, lysozyme, protease, alpha-toxin, fibrinolysin) were noted. A high resistance to tetracycline and penicillin was found in the strains isolated from the blood and the pleural cavity.
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PMID:[Biological properties of plasma-negative staphylococci isolated from patients in surgical departments]. 16 48

[3-H]Epinephrine binding to isolated purified rat liver plasma membranes is a reversible process. An initial peak in binding occurs at about 15 min and a plateau occurs by 50 min. Optimal binding occurred at a membrane protein concentration of 125mug. Rat liver plasma membranes stored at-70 degrees C up to 4 weeks showed no difference in epinephrine binding capacity as compared to control fresh membranes. Epinephrine binding to liver plasma membranes was decreased by 79% by phospholipase A2 (phosphatide acylhydrolase EC 3.1.1.4), 81% by phospholipase C (phosphatidylcholine choline phosphohydrolase EC 3.1.4.3) and 59% by phospholipase D (phosphatidylcholine phosphatidohydrolase EC 3.1.4.4). Trypsin and pronase digestion of the membrane decreased epinephrine binding by 97 and 47% respectively. In the presence of 10-3M Mg-2+ ions, increasing concentrations of QTP decreased epinephrine binding to liver plasma membranes. A maximal effect was demonstrated with 10-5M GTP, representing an inhibition of 52% of the control. In a Mg-2+ -free system, epinephrine binding was unaffected by GTP. However, in a Mg-2+ -free system, increasing concentrations of ATP cause increasing inhibition of hormone binding. ATP at 10-3 M reduced epinephrine binding to 28% of the control. GRP (10-5 M) was shown to inhibit epinephrine uptake rather than epinephrine release from the membrane. [3-H]Epinephrine binding to isolated rat epididymal fat cells shows an initial peak within 5 min followed by a gradual rise which plateaus after 60 min. Epinephrine binding increased nearly linearly with increasing fat cell protein concentration (40-200 mug protein). GTP (10-5 M) and ATP (10-4 M) decreased epinephrine binding to rat epididymal fat cells by 41%. Nearly complete inhibition of binding was demonstrated with 10-2-10-3M ATP. Epinephrine analogs that contain two hydroxyl groups in the 3 and 4 position on the benzene ring act as inhibitors of [3-H]epinephrine binding to rat adipocytes. Alteration of the epinephrine side chain has relatively little influence on binding. Analogs in which one of the ring hydroxyl groups is missing or methylated are poor inhibitors of [3-H]epinephrine binding. Alpha-(phentolamine and phenoxybenzamine) and beta-(propranolol and dichorisoproterenol) adrenergic blocking agents were tested with respect to their ability to influence [3-H]epinephrine binding and their influence on epinephrine-stimulated lipolysis. Only dichloroisoproterenol significantly inhibited epinephrine binding (by 25%). The two beta-adrenergic blocking agents caused an inhibition of epinephrine-stimulated glycerol release, with propranolol being most effective. Phentolamine and phenoxybenzamine had no significant effect on the epinephrine stimulation of glycerol release by fat cells.
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PMID:Hormone action at the membrane level. IV. Epinephrine binding to rat liver plasma membranes and rat epididymal fat cells. 16 9

Commercially available preparations of phospholipase C from Clostridium perfringens are commonly contaminated with theta haemolysin, one of a group of bacterial haemolysins called oxygen labile (O-labile) haemolysins. Treatment of erythrocyte ghosts and a mixed lipid dispersion containing cholesterol with commercially available phospholipase C in the absence of Ca-2+ and the presence of phosphate buffer and/or EDTA resulted in the formation and release of ring or arc-shaped structures. Highly purified phospholipase C, free of theta-haemolysin, produced no changes in the morphology of erythrocyte ghosts or lipid dispersions in the presence of phosphate or EDTA, but caused the formation of typical diglyceride droplets in the presence of Ca-2+ in the absence of these inhibitors. Ring structures, identical to those caused by commercial phospholipase C, were formed on addition of highly purified theta-haemolysin to erythrocyte ghost membranes, lipid dispersions containing cholesterol and cholesterol dispersions, but not on treatment of membranes from Micrococcus lysodeikticus. Heat-inactivated O-haemolysin (60 degrees C for 10 min) produced no such effects. The dimensions of rings and arcs displayed heterogeneity. The outside diameters in various preparations varied from approx. 27-58 nm with border thickness of 4.1-7.8 nm.
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PMID:Interaction of Clostridium perfringens theta-haemolysin, a contaminant of commercial phospholipase C, with erythrocyte ghost membranes and lipid dispersions. A morphological study. 16 11

A comparative ultrahistochemical investigation of the adepidermal granules of Salmo irideus, Lebistis reticulatus and Hynobius tokyoensis was carried out using enzyme digestion methods on epoxy-embedded sections. The granules of S. irideus larvae were decomposed by periodic acid, and digested by lipase without periodic acid pretreatmenetection of the granules. The secondary postosmificated granules were digested by lipase as in S; irideus, but complete decomposition by periodic acid was not observed in this experiment; Both periodic acid and lipase changed the shape of the adepidermal granules of H. tokyoensis to suggest partial digestion, but it appeared that these granules show rather stronger resistance to periodic acid and lipase than those of S. irideus. The granules of H. tokyoensis were completely digested when the sections were treated sequentially with phospholipase C, neuraminidase and lipase.
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PMID:Comparative ultrahistochemistry of the adepidermal granules of Salmo irideus, Lebistis reticulatus and Hynobiuo tokyoensis. Enzyme digestive experiment for the epoxy-embedded sections;. 16 31

The choline ester of a spin-labeled fatty acid, 8-doxylpalmitocylcholine, CH3--(CH2)7--CR-(CH2)6-- + COO--(CH2)2--N(CH3)3, where R is the paramagnetic 4',4'-dimethyloxazolidine-N-oxyl (doxyl) ring has been synthesized. 8-Doxylpalmitoylcholine blocks reversibly the depolarization of Electrophorus electroplaque elicited by the bath application of carbamylcholine. It slows down the initial rate of binding of the alpha-[3-H]toxin from Naja nigricollis to receptor-rich membranes fragments from Torpedo, and it displaces [3-H]acetylcholine bound to the cholinergic receptor site present in these fragments. Electron spin resonance spectra of 8-doxylpalmitoylcholine in the presence of the receptor-rich membrane fragments show complete immobilization of the spin label. Various cholinergic agents tested, including N. nigricollis alpha-toxin, reverse this immobilization, probably by displacing the 8-doxylpalmitoylcholine from its complex with the cholinergic receptor protein to the lipid phase of the membrane.
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PMID:Interaction of a spin-labeled long chain acylcholine with the cholinergic receptor protein in its membrane environment. 16 83

Aerolysin, a hemolytic and lethal exotoxin of Aeromonas hydrophila, was analyzed for amino acids. Assuming 8 histidine residues/mol, the purified toxic protein has, by summation, a molecular weight of 49,000, a value in agreement with earlier estimates by other methods. Erythrocytes from different animal species differ greatly in sensitivity to aerolysin's lytic action. There is some correlation between sensitivity and phosphatidyl choline content. Erythrocyte membranes of different species bind the toxin, and the efficiency of binding is a function of sensitivity to lysis. Binding is temperature independent, is not dependent upon membrane sialic acid, and is decreased by prior treatment with phospholipase C and proteases. Preparations of aerolysin convert substantial amounts of membrane phosphorus to water-soluble form; the conversion is concentration and temperature dependent. Most of the conversion is attributable to contaminating phospholipase(s) that is separable from the toxin. Aerolysin purified by electrophoresis in polyacrylamide gel retains some phospholipase activity, and this activity may or may not be a contaminant.
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PMID:Interactions between aerolysin, erythrocytes, and erythrocyte membranes. 16 17

A floatation centrifugation procedure is described by which antibodies and non-specific rubella virus haemagglutination inhibitors can be completely separated. Using this method it was shown that false positive reactions occur with the conventional pretreatments of sera for removing inhibitors, especially with the heparin-McCl2 procedure. Other methods for removal of inhibitors were examined in view of recent knowledge about the chemical nature of the inhibitors. Treatment with phospholipase C proved useful for disclosure of false positive reactions, while floatation centrifugation was the most sensitive method for demonstration of low antibody concentrations.
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PMID:False positive rubella virus haemagglutination inhibition reactions: occurrence and disclosure. 16 69

When isolated mitochondria or microsomes from rat liver were treated with phospholipase C, the incorporation of radioactive phospholipid precursors was markedly enhanced, presumably as a result of production of diglycerides by hydrolysis of endogenous phospholipids. Incorporation of CDP[14C]choline into lecithin in rat liver or BHK-21 mitochondria could be attributed to residual contamination from elements of the endoplasmic reticulum, with added diglycerides or with endogenous diglycerides produced by the phospholipase C treatment. A similar stimulation of [gamma32P]ATP incorporation into phospholipids was observed with exogenous or endogenous diglycerides, but the mitochondrial diglyceride kinase in either case was also related to the degree of microsomal contaminants. It was concluded that previous studies showing negligible capacity of mitochondria for lecithin biosynthesis de novo were not explainable on the basis of limited accessibility of added diglycerides, and that formation of phosphatidic acid by diglyceride kinase was not of significance in rat liver mitochondria.
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PMID:Biosynthesis of mitochondrial phospholipids using endogenously generated diglycerides. 16 19

The disruption of the molecular organization of the plasma membrane of leukocytes by phagocytosable particles, or by agents such as surfactants, antibodies, phospholipase C, fatty acids and chemotactic factors, leads to a stimulation of the phagocyte oxidative metabolism. Concanavalin A (Con A) has been used as a tool to study the mechanism of this metabolic regulation. The binding of Con A to the surface of polymorphonuclear leukocytes (PMNL) or macrophages produces a rapid enhancement of oxygen uptake and glucose oxidation through the hexose monophosphate pathway (HMP). This is explained by an activation of the granular NADPH oxidase, the key enzyme in the metabolic stimulation. The effect of Con A is not due to endocytosed lectin, since Con A covalently coupled to large sepharose beads still acts as stimulant. The metabolic changes caused by Con A are reversible. If, after the onset of stimulation, sugars with high affinity for Con A are added to the leukocyte suspension, the activity of granular NADPH oxidase and the rate of respiration and glucose oxidation return to their resting values. The metabolic burst, while partially supressed by treatment of PMNL with iodoacetate, sodium flouride and cytochalasin B, is slightly increased by colchicine. Con A induces a selective release of granular enzymes (beta-glucuronidase, peroxidase, alkaline phosphatase) from PMNL, whereas no leakage of cytoplasmic enzymes is observed. The enzyme release is inhibited by iodoacetate and by drugs known to increase cell levels of cyclic AMP. Based on a current view of the mode of interaction between Con A and cell surfaces, a model of the metabolic disruption of leukocytes is presented.
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PMID:Concanavalin A as a probe for studying the mechanism of metabolic stimulation of leukocytes. 16 45

1. Pure or impure C-type phospholipases hydrolysed rat liver microsomal phosphatides in situ at 5 degrees or 37 degrees C. At 5 degrees C mean hydrolysis of total phospholipids was 90% by Bacillus cereus and 75% by Clostridium perfringens (Clostridium welchii) C-type phospholipases. 2. Four degrees of inhibition of glucose 6-phosphatase (D-glucose 6-phosphate phosphohydrolase; EC 3.1.3.9) resulted. (a) At 37 degrees C inhibition was virtually complete and apparently irreversible. (b) At 5 degrees C phospholipase C inhibited 50-87% of the activity expressed by intact control microsomal fractions. (c) Bovine serum albumin present during delipidation alleviated most of this inhibition: at 5 degrees C phospholipase C plus bovine serum albumin inhibited by 0-35% (mean 18%):simultaneous stimulation by the destruction of its latency seems to offset glucose 6-phosphatase inhibition, sometimes completely. (d) If latency was first destroyed, phospholipase C plus bovine serum albumin inhibited 30-50% of total glucose 6-phosphatase activity at 5 degrees C. Only this inhibition is likely largely to reflect the lower availability of phospholipids, essential for maximal enzyme activity, as it is virtually completely reversed by added phospholipid dispersions. Co-dispersions of phosphatidylserine plus phosphatidylcholine (1:1, w/w) were especially effective but Triton X-100 was unable effectively to restore activity. 3. Considerable glucose 6-phosphatase activity survived 240min of treatment with phospholipase C at 5 degrees C, but in the absence of substrate or at physiological glucose 6-phosphate concentrations the delipidated enzyme was completely inactivated within 10min at 37 degrees C. However, 80mM-glucose 6-phosphate stabilized it and phospholipid dispersions substantially restored thermal stability. 4. It is concluded that glucose 6-phosphatase is at least partly phospholipid-dependent, and complete dependence is not excluded. For reasons discussed it is impossible yet to be certain which phospholipid class(es) the enzyme requires for activity.
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PMID:Inhibition of glucose 6-phosphatase by pure and impure C-type phospholipases. Reactivation by phospholipid dispersions and protection by serum albumin. 16 86


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