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)

1. Phospholipase C (EC 3.1.4.3) from Clostridium novyi (oedematiens) type A was purified 2000-fold by (NH4)2SO4 precipitation, DEAE-Sephadex treatment in a batchwise system and Sephadex G-100 column chromatography. 2. The purified preparation had a specific activity of 95 mumol per min per mg protein toward phosphatidylcholine. This preparation was free from protease, lipase and oxygen-labile delta-hemolysin. 3. Phosphatidylcholine was hydrolyzed at the highest rate, while sphingomyelin and lysophosphatidylcholine were hydrolyzed at much lower rates. 4. Sodium deoxycholate and divalent cations such as Mg2+ and Ca2+ were extremely effective in stimulating phosphatidylcholine-hydrolyzing activity of this enzyme. 5. This enzyme hemolyzed horse red cells by hydrolyzing phosphatidylcholine, spingomyelin and phosphatidylethanolamine.
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PMID:Phospholipase C from Clostridium novyi type A. I. 24 23

Phosphoinositide-specific phospholipase C (PI-PLC) from human platelet cytosol was purified 190-fold to a specific activity of 0.68 mumol of phosphatidylinositol (PI) cleaved/min per mg of protein. It hydrolyses PI and phosphatidylinositol 4,5-bisphosphate (PIP2), but not phosphatidylcholine, phosphatidylserine or phosphatidylethanolamine. The enzyme exhibits an acid pH optimum of 5.5 and has a molecular mass of 98 kDa as determined by Sephacryl S-200 gel filtration. It required millimolar concentrations of Ca2+ for PI hydrolysis, whereas micromolar concentrations are optimal for PIP2 hydrolysis. Mg2+ could substitute for Ca2+ when PIP2, but not PI, was used as the substrate. EDTA was more effective than EGTA in inhibiting the basal PI-PLC activity towards PIP2. Sodium deoxycholate strongly inhibits the purified PI-PLC activity with either PI or PIP2 as substrate. Ras proteins, either alone or in the form of liposomes, have no effect on PI-PLC activity.
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PMID:Characterization of phosphoinositide-specific phospholipase C from human platelets. 282 91

Phosphatidylinositol-specific phospholipase C (PI-PLC) was characterized in rat myocardium, and the effect of hypoxia on its activity was investigated. It had a substrate specificity toward phosphatidylinositol (PI) and was predominantly located in cytosol. Its optimal pH was 7.4 and it required 5 mM of Ca2+ for maximum activity, but did not hydrolyze phosphatidylcholine (PC), phosphatidylethanolamine (PE), or phosphatidylserine (PS). Vmax and Km were 51.5 nmol/mg/min, and 231 microM, respectively. Sodium deoxycholate increased its activity at a concentration of 0.05%, while Triton X-100 inhibited its activity at any concentrations examined. PI-PLC was partially purified 260 fold over the crude cytosol, with ammonium sulphate fractionation, DEAE-cellulose, Sephadex G-100, Hydroxylapatite, and Sephadex G-150 column chromatographies. In order to elucidate the biochemical function of myocardial PI-PLC in hypoxia, PI-PLC along with phospholipase A2 (PLA2) was investigated in N2 gas-saturated buffer up to for 24 hours. The activity of PI-PLC did not change during the first 2 hours, and then gradually attenuated. Substrate specificity or subcellular localization of PI-PLC unchanged during 24 hour 9 of hypoxia. PLA2 was predominantly located in microsome and had a substrate specificity toward PE in normoxic state. In hypoxia, on the other hand, it hydrolyzed PC besides PE and was activated on and after 2 hours of hypoxic incubation. PI-PLC did not seem to contribute in releasing arachidonate from membrane lipid-bilayers during myocardial ischemia. But some biochemical mechanism suggested to inhibit its activity protecting the abrupt cell damage.
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PMID:[Phosphatidylinositol-specific phospholipase C in hypoxic rat myocardium]. 282 21

The presence of endogenous phospholipase A (PL-A) activity of U. urealyticum hydrolyzing the acyl ester bond and phospholipase C (PL-C) activity hydrolyzing the phosphodiester bond is primarily localized in the membranes of ureaplasmas. Characterization of the membrane PL-A and PL-C activity in exponential growing cells of serovars 3, 4, and 8 was investigated. The pH optimum was about 8.5-9 for phospholipase A1 (PL-A1) in the three serovars. A more acidic pH optimum of 6 was observed for phospholipase A2 (PL-A2) enzymes in serovars 3 and 4. However, a very significant stimulation of PL-A2 activity in serovar 8 occurred around pH 7. The specific activity of PL-A2 was always 50-100 fold higher than PL-A1 activity in the pH range studied. Ca2+ ions only slightly stimulated PL-A1 activity in all 3 serovars. PL-A1 activity was stimulated about 6-fold from 0.5-0.8 mM Ca2+ ion concentrations for serovar 3 and 12-fold for serovar 8. Only lower concentrations (0.2-0.4 mM) of calcium stimulated PL-A2 activity in serovar 4. EDTA inhibition corresponded to Ca2+ stimulation for PL-A1 activity for serovars 3 and 8. A general stimulation of PL-A1 activity by diethyl ether was evident but the degree of stimulation varied with the serovar. Sodium deoxycholate enhanced PL-A activity of serovars 4 and 3, but partially inhibited that of serovar 8. PL-A activity in the three serovars were not significantly affected by p-hydroxymercuribenzoate, a marker of -SH groups in the enzyme. All 3 serovars were inactivated by heat. A broad pH optimum for PL-C activity was evident around 7-8. Diethyl ether enhanced PL-C activity of serovar 8. Sodium deoxycholate and heat were inhibitory to PL-C activity. The results demonstrate that the major characteristics of ureaplasma membrane bound PL-A and PL-C are basically similar to those of other mollicutes and bacteria. However, the major differences in the specific characteristics of specially PL-A1 and PL-A2 suggest that the ureaplasma phospholipases are unique enzymes different from the phospholipases of bacteria. Both the PL-A and PL-C enzymes function over the broad range at which ureaplasma can grow, pH 5-9 essential for survival. The ureaplasma PL-As are also markedly different from one serovar to another. This variation in specific activity could contribute significantly to differences in virulence among serovars in specific host milieus. There is significant variation from acidic pH of the vagina and alveolar surface of the lung to a more neutral pH of the endometrium and placenta. There are marked differences in calcium concentrations under specific circumstances in various host tissues. Thus the differences in specific activity among the phospholipases of the serovars of U. urealyticum may be of physiological importance in interactions with host tissues and pathogenesis of disease.
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PMID:Characterization of phospholipase A1, A2, C activity in Ureaplasma urealyticum membranes. 1063 Jun 35