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)

Crotoxin is a potent neurotoxin from the venom of Crotalus durissus terrificus. It is composed of two subunits: a basic phospholipase A2 with low toxicity (component B) and an acidic protein seemingly devoid of intrinsic biological activity (component A). Crotoxin and its isolated phospholipase subunit block the depolarisation caused by cholinergic agonists on the isolated electroplaque from Electrophorus electricus. The other component, which is inactive when applied alone, enhances the pharmacological activity of the phospholipase when the two components are used together. Crotoxin also blocks the increase of 22Na+ efflux caused by carbamylcholine from excitable microsacs prepared from Torpedo marmorata electric organ. Crotoxin therefore acts postsynaptically, but does not interfere with the binding of alpha-toxin from Naja nigricollis to the nicotinic cholinergic receptor site. Instead, like local anesthetics, it stabilizes a desensitized form of the acetylcholine receptor characterized by its high affinity for agonists. The phospholipase component B binds in a non-saturable manner to receptor-rich membranes. In contrast, component A does not bind to acetylcholine receptor-rich membranes, but completely prevents the non-saturable binding of component B. When the two components are applied together, a saturable binding of the latter is observed with the acetylcholine receptor-rich membranes.
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PMID:Postsynaptic effects of crotoxin and of its isolated subunits. 49 10

The effects of some antibiotics on activities of phospholipase A2, B and C were investigated in vitro. Tetracyclines, macrolides, chloramphenicol and carbenicillin inhibited the activity of Crotalus adamanteus phospholipase A2 towards phospholipids of egg-yolk emulsions. When the ability to inhibit the activity of Penicillium notatum phospholipase B towards mixed micelles of phosphatidylcholine and Triton X-100 was investigated, polymyxin B was found to be inhibitory while chloramphenicol and carbenicillin were found to stimulate the activity of the phospholipase. The activity of Bacillus cereus phospholipase C towards the mixed micelles was inhibited by bleomycin, oleandomycin and chloramphenicol.
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PMID:In vitro actions of some antibiotics on phospholipases. 54 Dec 66

Pronase digested sheep red blood cell stromata were employed as probe in order to investigate erythrocyte membrane arrangement by immunological way. Antiserum from rabbits immunized with erythrocyte ghost pronase residue assayed for its hemolytic activity against intact sheep red cells, showed an high titer, in a good agreement with the presence in the same residue of externally located membrane antigens. Immunoelectrophoretic analysis was performed between the solubilized residue and precipitins produced by rabbits immunized respectively with the following antigens: intact sheep red blood cells (SRBC), sheep erythrocyte stromata (SRBCS), lipid complex (LC), sphingomyelin complex (SF), stromata after phospholipase A treatment (SPLA), stromata after phospholipase C treatment (SPLC), stromata after phospholipases A and C treatment (SPLAC), and pronase treated stromata (SP). Antigen/antibody reaction with anti-SP antiserum showed an additional precipitation line: this fact is discussed in view of a possible enrichment of the fraction after pronase stromata digestion, and/or enhancement of the immunogenicity.
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PMID:Sheep red blood cell membrane structure: an immunological probe. 65 97

The phospholipid distribution in the membrane of Bacillus amyloliquefaciens was studied by using phospholipase C (B. cereus), phospholipase A2 (Crotalus), and the nonpenetrating chemical probe trinitrobenzenesulfonic acid. After treatment of intact protoplasts of B. amyloliquefaciens with either phospholipase, about 70% of total membrane phospholipid was hydrolyzed; specifically, about 90, 90, and 30% of phosphatidylethanolamine, phosphatidylglycerol, and cardiolipin, respectively. Under these conditions, protoplasts remained intact and sealed. However, when protoplasts that were permeabilized by cold-shock treatment were incubated with either of the phospholipases, up to 80% of cardiolipin was hydrolyzed and phosphatidylglycerol and phosphatidylethanolamine were hydrolyzed virtually to completion. In intact cells, 92% of the phosphatidylethanolamine could be labeled with trinitrobenzenesulfonic acid under conditions in which the reagent did not penetrate the membrane to any significant extent. These results indicate that 70% of total phospholipid of this bacillus exists in the outer half of the bilayer. The distribution of phosphatidylethanolamine in this bilayer is highly asymmetric with it being located predominantly in the outer half. The results with phospholipases suggest that the distributions of cardiolipin and phosphatidylglycerol are also asymmetric but independent confirmation of this is required.
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PMID:Membrane phospholipid asymmetry in Bacillus amyloliquefaciens. 68 Dec 77

Treatment with phospholipase A2 of crude or partially purified preparations of the glucocorticoid receptor of rat liver results in an inactivation of the receptor, which cannot be attributed to contaminating proteases. Similar enzymatic treatment of the progesterone receptor of rabbit uterus does not affect its steroid-binding activity. At various stages during purification the preparations of glucocorticoid receptor contain 10 to 50-fold higher concentrations of lipid phosphate than the corresponding preparations of progesterone receptor, suggesting that the effect of phospholipase A2 on the hepatic receptor could be mediated by lysophosphatides produced during hydrolysis of endogeneous phospholipids. In fact, mixing experiments show that in the presence of the glucocorticoid receptor, phospholipase A2 also inactivated the progesterone receptor. Both partially purified receptors are inactivated by similar concentrations of added lysophosphatides but are not affected by incubation with phospholipase C, which does not produce ionic detergents. In addition, the effects of phospholipase A2 and of added lysophosphatides can be overcome by an excess of bovine serum albumin, indicating that free lysophosphatides are involved in receptor inactivation, possibly due to their strong detergent properties.
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PMID:Effect of phospholipases and lysophosphatides on partially purified steroid hormone receptors. 72 Oct 66

1. The composition and metabolism of phospholipids were studied in various tissues from both normal and dystrophic mice of the 129 ReJ strain. Phospholipids extracted from forebrain, spinal cord, sciatic nerve and plasma were fractionated by t.l.c. and measured. 2. Very significant alterations were found in the choline phospholipids from these tissues, except forebrain. Plasma phosphatidylcholine in the dystrophic mouse was increased by 38%. There was a 2-fold increase in lysophosphatidylcholine in the spinal cord of dystrophic mice. The sciatic nerve showed a marked decrease in sphingomyelin content, which is approximately half of that in the controls. 3. Five enzymes involved in phosphatidylcholine metabolism [namely cholinephosphotransferase (EC 2.7.8.2); phospholipases A (EC 3.1.1.4, EC 3.1.1.32); lysophospholipase (EC 3.1.1.5); lysophosphatidylcholine acyltransferase (EC 2.3.1.23); phospholipase C (EC 3.1.4.3)] were studied in tissue preparations from forebrain, spinal cord, sciatic nerves, gastrocnemius muscles and liver. 4. Activities of phospholipases A and C were significantly increased, about 5-fold and 60% respectively, in gastrocnemius muscle of dystrophic mice compared with controls. Phospholipases A also showed 50% higher activity in the sciatic nerves of dystrophic than of normal mice. Lysophosphatidylcholine acyltransferase activities were significantly increased in the sciatic nerves and spinal cord, by 50-100% over that of the controls. The forebrain and spinal cord from dystrophic mice, however, had only 60% of lysophospholipase activities of that of the normal control. Cholinephosphotransferase activity was unchanged in these tissues from both normal and dystrophic mice. 5. It is suggested that are number of features of mouse muscular dystrophy related to altered membrane structure and function can be rationalized in terms of changes in lipid composition and metabolism.
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PMID:Phospholipid composition and metabolism in mouse muscular dystrophy. 72 3

rac-Phosphatidyl carnitine and rac-phosphatidyl beta-methylcholine were synthesized by direct condensation of phosphatidic acid and the appropriate alcohols in the presence of 2,4,6-triiso-propylbenzenesulphonylchloride and pyridine. Tetraphenylborates of the quarternary ammonium compounds beta-methylcholine and carnitine benzyl ester were shown to be particularly convenient for synthesis in homogeneous phase. Physical and chemical properties of the two phosphoglycerolipids and some intermediates were described. Phosphatidyl carnitine and phosphatidyl beta-methylcholine were hydrolyzed by phospholipase A2 (phosphatide acyl-hydrolase, EC 3.1.1.4), pancreatic lipase (triacylglycerol acyl-hydrolase, EC 3.1.1.3), and phospholipase C from Bacillus cereus (phosphatidylcholine cholinephosphohydrolase, EC 3.1.4.3). Neither hydrolysis nor transphosphatidylation of phosphatidyl carnitine and phosphatidyl beta-methylcholine was achieved by phospholipase D (phosphatidylcholine phosphatidohydrolase, EC 3.1.4.4). The occurrence of phosphatidyl carnitine in embryonic chicken tissue was suggested by comparison with the synthesized compound. Phosphatidyl carnitine could not be detected in the tissue of rat embryos.
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PMID:Synthesis and properties of phosphatidyl carnitine and phosphatidyl beta-methylcholine. 80 79

The degradation of red cell stroma phospholipids by phospholipase A2 is accompanied by a concomitant fall in the activity of the Rh antigens, c, D and e. The action of phospholipase C on stroma also brings about a fall in D antigen activity. Anti-D bound to the red cells protects the D antigen from inactivation by phospholipase A2.
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PMID:Loss of rh antigen activity following the action of phospholipase A2 on red cell stroma. 80 74

Lecithin agar was developed on which phospholipase C produced turbid zones and phospholipase A produced clear zones. Reactions on lecithin agar agreed 74% of the time with reactions in egg yolk broth. On lecithin agar, interpretation was easier, phospholipase A was detectable, and opaque zones were visible 1 or 2 days earlier than on egg yolk agar. All constituents of the medium can be autoclaved.
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PMID:Lecithin agar for detection of microbial phospholipases. 81 60

1. The effects of phospholipases A from bee venom and from porcine pancreas and of phospholipases C from Clostridium welchii and Bacillus cereus on active and passive membrane properties of Aplysia neurones have been studied. Consistent alterations in electrical membrane properties were found following intracellular application of three of these enzymes.2. Bee venom phospholipase A produced a rapid decrease of membrane potential and resistance. Voltage clamping revealed a marked depression of peak transient current with little or no effect in the late outward current.3. Mammalian phospholipase A was found ineffective in changing either the resting or active membrane properties.4. Phospholipase C from Bacillus cereus led to a strong hyperpolarization and a fall in membrane resistance. Voltage clamping revealed a marked increase in the late outward current.5. Neurones injected with Clostridium welchii phospholipase C manifested a several-fold rise in resting membrane resistance as well as a tendency to slight hyperpolarization.6. All enzymes were ineffective when externally applied.7. It is tentatively concluded that the internally applied phospholipases affect specific ionic permeabilities both in the resting and active excitable membrane. Various mechanisms by which the differing actions of enzymes of the same type could be explained are discussed.
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PMID:Membrane properties of Aplysia neurones intracellularly injected with phospholipases A and C. 87 92


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