Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.1.4.1 (phosphodiesterase)
 18,767 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Phosphatidylinositol phosphodiesterase activated by diacylglycerol is substantially inhibited by all phospholipids containing a phosphocholine head group, including phosphatidylcholine, hydrogenated phosphatidylcholine, choline plasmalogen, lysophosphatidylcholine, lysocholine plasmalogen, sphingomyelin and sphingosylphosphocholine. The sphingosine-containing phospholipids are the most inhibitory. Phosphatidic acid does not inhibit, and phosphatidylethanolamine activates the hydrolysis still further. Sphingomyelin is highly inhibitory to a diacylglycerol-stimulated intestinal mucosal phospholipase A2, or a liver lysosomal phospholipase A1 + A2, both hydrolysing a phosphatidylcholine substrate. Sphingomyelin [20% molar (20 mol of sphingomyelin/80 mol of phosphatidylethanolamine)] activates phosphatidylethanolamine hydrolysis by intestinal mucosal phospholipase A2, and then at higher concentrations (40% molar) substantially inhibits the activity. The results are discussed in relation to possible molecular reorganizations brought about in the hydrated phospholipid substrate complex, and in particular the possible stabilizing role of sphingomyelin in the maintenance of membrane structure, and hence in the modulation of phospholipase activity.
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PMID:The inhibition of diacylglycerol-stimulated intracellular phospholipases by phospholipids with a phosphocholine-containing polar group. A possible physiological role for sphingomyelin. 299 96

[3H]Myristoyl-labeled variant surface glycoprotein (VSG) has been isolated from Trypanosoma brucei by reverse phase high performance liquid chromatography and used as substrate for the conversion by trypanosomal enzymes of membrane-form VSG to soluble VSG. Conversion is detected by the release of myristoyl-containing lipids. The major lipolytic enzyme of T. brucei, phospholipase A1, is effective for the hydrolysis of myristoyl esters of p-nitrophenol, in a colorimetric assay. However, the phospholipase is unable to cleave the myristoyl ester linkage of VSG. The phospholipase can be separated from the myristoyl-releasing activity of trypanosome homogenate by centrifugation, affinity chromatography, and anion-exchange chromatography. Elution profiles on anion-exchange high performance liquid chromatography also indicate that the phospholipase is inactive against VSG. A small amount of myristoyl-releasing activity associated with the purified phospholipase is probably due to contamination with a phosphodiesterase which releases myristoyl-containing diglyceride from VSG.
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PMID:The phospholipase A1 of Trypanosoma brucei does not release myristate from the variant surface glycoprotein. 394 70

1. A rat brain supernatant and microsomal fraction contained a phospholipase A1 enzyme which hydrolysed phosphatidylinositol at pH 8 in the absence of calcium. Triolein and phosphatidylcholine were not attacked under the same incubation conditions. 2. No evidence could be obtained for a phospholipase A2 in the microsomal preparation, and in the presence of Ca2+ the release of fatty acid observed was due to phosphatidylinositol phosphodiesterase followed by diacylglycerol lipase action. 3. Brain phosphatidylinositol phosphodiesterase showed extensive activity in the alkaline range (7-8.5) as well as at pH 5-5.5. The activity at higher pH values required higher calcium concentrations and disappeared on purification of the soluble enzyme by ammonium sulphate fractionation. 4. In general the ratio between inositol 1,2-(cyclic)phosphate and inositol 1-phosphate produced by phosphodiesterase action decreased with increasing pH.
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PMID:The catabolism of phosphatidylinisitol by an EDTA-insensitive phospholipase A1 and calcium-dependent phosphatidylinositol phosphodiesterase in rat brain. 627 69

1. The secretion from sheep pancreas and a supernatant fraction prepared from the gland contained an EDTA-insensitive acid phospholipase A1 which readily deacylated phosphatidylinositol (pH optimum, 5.3), 1-acylglycerophosphoinositol and phosphatidic acid, but had limited action of phosphatidylcholine and phosphatidylethanolamine even with deoxycholate present. The enzyme was not a triacylglycerol lipase. 2. The action of the phospholipase A1 on phosphatidylinositol was inhibited effectively by Ca2+ and Mg2+, probably by interaction of these ions with the substrate. 3. In the presence of calcium the decomposition of phosphatidylinositol and lysophosphatidylinositol by the supernatant fraction was overwhelmingly by phosphodiesterase action (EC 3.1.4.10), producing inositol monophosphate and its cyclic derivative. Its pH optimum was about 6.0 but with considerable activity extending to pH 8.5. 4. The phosphodiesterase was not secreted in the pancreatic juice.
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PMID:Hydrolysis of phosphatidylinositol by pancreas and pancreatic secretion. 706 59

Deacylation of the phosphatidylcholine fraction in plasma membranes of rat thymocytes and human blood lymphocytes was studied as well as its relationship to the activation of phosphoinositide-specific phosphodiesterase at early stages of mitogen-initiated phosphoinositide cycle. The data indicate that in lymphocyte membranes, enzymatic system of cascade deacylation of the phosphatidylcholine fraction includes calcium-activated phospholipase A1 and lysophospholipase. The enzyme system contributes to the rapid and reversible modification of the lipid bilayer of lymphocyte plasma membrane and can cooperate with phosphoinositide-specific phosphodiesterase during its activation at early stages of the initiation of phosphoinositide pathway during translocation of the external mitogenic signal.
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PMID:[Catabolism of membrane phosphatidylcholines during early stages of mitogenic initiation of phosphoinositide cycle in lymphocytes]. 896 16

It was found that at the exposure of Vipera lebetina snakes (during 10 days for 30 min daily) to SMF (0.15 T1) the specific activity of venom phospholipase A1, A2 and phosphodiesterase C increased by 20.6 +/- 2.8; 31.7 +/- 3.2 and 32.7 +/- 1.3% correspondingly. The above mentioned changes of venom enzyme activity were accompanied with the decrease of its total protein amount by 31.6 +/- 2.2%. It could be supposed that the described changes are able to cause significant changes in the total metabolic activity of cells and the organism as a whole.
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PMID:[A permanent magnetic field alters the phospholipase activity in the snake venom from Vipera lebetina]. 1103 91