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:3.1.1.5 (neuropathy target esterase)
1,070 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The murine macrophage (M phi) cell line, P388D1, was employed as a source of M phi phospholipases in order to characterize the enzymatic properties and subcellular localization of these enzymes because of their importance for prostaglandin biosynthesis. Phospholipase activity was assessed with dipalmitoylphosphatidylcholine (DPPC) as substrate. Phospholipases were characterized with respect to divalent cation dependence, pH optima, and localization in subcellular compartments using linear sucrose gradients. By these criteria a number of different phospholipases were identified. Most importantly, a single Ca2+-dependent activity with a pH optimum of 8.8 was identified in membrane-rich fractions (plasma membrane, mitochondria, and endoplasmic reticulum) and could be clearly separated from the remaining activities, which are Ca2+ independent and exhibit pH optima of 7.5, 5.1, and 4.2. The phospholipases with acidic pH optima may be associated with subcellular components containing lysosomal enzymes and both phospholipase A1 and phospholipase A2 activities are observed. In contrast, the phospholipase activity with a pH optimum of 7.5 sediments with the cytosolic proteins and is inhibited by 5 mM Ca2+. No significant phospholipase C activity was detected in assays performed with or without added Ca2+ at pH's 4.2, 5.1, 7.5, or 8.8 using DPPC as substrate. However, the P388D1 cells do contain a lysophospholipase that is at least 20 times more active than the phospholipase A activities identified. Its presence must be taken into account in evaluating the positional specificities and properties of the macrophage phospholipases.
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PMID:Phospholipase activities of the P388D1 macrophage-like cell line. 398 20

The phospholipase A2 and lysophospholipase A1 activities were determined in various mixtures. When estimating the phospholipase A2 activity in venoms of snakes and insects the known methods based on measuring a change in the optical density of the egg yolk suspension are not acceptible if in investigated object besides phospholipases lysophospholipases are present (venoms of viper and giant hornet). In this case anomalous curves of changes in the system optical density in time are obtained. At the same time the analysis of such curves revealed that the method can be rather sensitive for determining lysophospholipases in venoms, as well as in phospholipase preparations of different purification, including electrophoretically homogeneous preparations. The results obtained enabled us to estimate the content of phospholipase A2 and lysophospholipase A1 in the venom of giant hornet and in its fractions, obtained during isolation and purification of the concerned enzymes.
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PMID:[Determination of phospholipase A2 and lysophospholipase A1 in a mixture]. 403 60

The effects of hyper- and hypothyroidism on enzyme activities involved in phospholipid metabolism in the rat liver were studied. Hyperthyroidism significantly decreases activities of both microsomal acyl-CoA:glycero-3-phosphate acyltransferase (GPAT) (34%, p less than 0.01) and microsomal acyl-CoA:1-acylglycero-3-phosphocholine acyltransferase (GPCAT) (28-33%, p less than 0.01). This may contribute to the decreased proportions of certain unsaturated fatty acids found in microsomal phosphoglycerides in hyperthyroidism. Mitochondrial GPAT, phospholipase A2 and cytosol lysophospholipase are unaffected by hyperthyroidism. In contrast, hypothyroidism stimulates mitochondrial GPAT (38%, p less than 0.01) and microsomal GPCAT (14-19%) activities but decreases both mitochondrial phospholipase A2 (36%, p less than 0.01) and cytosol lysophospholipase (56%, p less than 0.01) activities. The increased GPCAT activity may contribute to the increased proportions of certain unsaturated fatty acids found in microsomal phosphoglycerides in hypothyroidism. Triiodothyronine (T3) treatment of the hypothyroid rat (25 micrograms/100 g body weight/day for four days) corrected phospholipase A2 and lysophospholipase activities to the level of the control rat, but failed to correct the increased mitochondrial GPAT activity and not only corrected but lowered GPCAT activity to the level of the hyperthyroid rat.
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PMID:Influence of hypo- and hyperthyroidism on rat liver glycerophospholipid metabolism. 409 20

We have studied the effect of streptozotocin (SZ)-induced diabetes on fatty acyltransferase and phospholipase enzyme activities involved in the synthesis and degradation of rat liver phosphoglycerides. Neither mitochondrial nor microsomal acyl-CoA:glycerol 3-phosphate acyltransferase (GPAT) activity was altered, although insulin treatment stimulated mitochondrial GPAT activity. However, microsomal acyl-CoA:1-acylglycerol 3-phosphate acyltransferase (1-acyl-GPAT) activity increased (24-33 per cent, p less than 0.01) in the diabetic animals using 3 different acyl-CoA donors: palmitoyl-CoA, oleoyl-CoA and linoleoyl-CoA. SZ-induced diabetes also increased acyl-CoA;1-acylglycerol 3-phosphorylcholine acyltransferase (GPCAT) activity (38-45 per cent, p less than 0.01) with 3 different acyl-CoA donors: oleoyl-CoA, linoleoyl-CoA and arachidonoyl-CoA. 1-acyl-GPAT and GPCAT activity returned to normal with insulin treatment. In contrast to the increased activity of the microsomal fatty acyl-transferases 1-acyl-GPAT and GPCAT, SZ-induced diabetes decreased mitochondrial phospholipase A2 activity and lysophospholipase activity (49-70 per cent, p less than 0.01). Insulin treatment of the diabetic rats corrected the decreased lysophospholipase and stimulated phospholipase A2 activity 35 per cent higher than controls. Since microsomal 1-acyl-GPAT and GPCAT are known to have higher activity toward unsaturated fatty acyl-CoA donors, the increased GPCAT activity coupled with the decreased lysophospholipase activity and the increased 1-acyl-GPAT activity in diabetes would tend to increase the formation of newly synthesized phospholipids containing unsaturated fatty acids. This mechanism plus the decreased fatty acid desaturase (4) may be the factors which alter the fatty acid composition of phosphoglycerides in diabetic rat liver microsomes.
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PMID:Effects of streptozotocin-induced diabetes on phosphoglyceride metabolism of the rat liver. 639 59

Lysolecithin (lysoglycerophosphocholine, LPC) was isolated from rat cerebral cortex and quantitatively analyzed at various times after postdecapitative ischemic treatment. In addition, different procedures for extraction and analysis of the LPC in brain were evaluated. Results indicated that LPC can be quantitatively extracted into the organic phase using the conventional extraction procedure with chloroform-methanol (2:1, vol/vol). However, care should be taken to avoid using strong acids, which can hydrolyze the alkenylether side chain of the plasmalogens, resulting in the release of 2-acylphospholipids. Quantitative GLC analysis using myristoyl-LPC as internal standard revealed a level of 1.8 nmol LPC/mg protein in brain with acyl groups comprised mainly of 16:0, 18:0, and 18:1. The acyl group profile reflects that the LPC are derived mainly from phospholipase A2 action. An increase of 46% in the LPC level was observed at 1 min after ischemic treatment, but this was followed by a steady decline. Ischemia induced an increase in the LPC species that are enriched in 18:0 and 18:1 fatty acids. The transient appearance of LPC during ischemia further suggests that this phospholipid is undergoing active turnover, possibly hydrolysis by the lysophospholipase. This mechanism of action may account, at least in part, for the increase in both saturated and unsaturated fatty acids during the early phase of the ischemic treatment.
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PMID:On the status of lysolecithin in rat cerebral cortex during ischemia. 647 Jul 8

In view of the importance of phospholipids as a source of precursor fatty acids for the high prostaglandin synthesis in the renal inner medulla, we studied pathways of phospholipid esterification and degradation in the rat inner medulla. De novo acylation of [14C]arachidonate occurred predominantly in position 2 of phosphatidylcholine in the microsomal fraction. This newly esterified [14C]arachidonate was accessible to deacylation by a microsomal phospholipase A2 (EC 3.1.1.4) with alkaline optimum which was Ca2+-dependent and resistant to 0.1% deoxycholate. No phospholipase A1 (EC 3.1.1.32) activity against endogenous labeled phosphatidylcholine could be demonstrated in the microsomal fraction. When exogenous phosphatidylcholine labeled at position 2 was deacylated by renomedullary homogenates, labeled free fatty acid but no labeled lysophosphatidylcholine was recovered in the reaction products. This could be attributed to further degradation of generated lysophosphatidylcholine by a cytosolic lysophospholipase (EC 3.1.1.5). Sodium deoxycholate at a concentration of 0.1% or higher inhibited the lysophospholipase and allowed the demonstration of both A2 and A1 alkaline phospholipase activities in the homogenate. The major in vitro pathway of lysophosphatidylcholine disposition is further degradation by a cytosolic lysophospholipase, while reutilization for phosphatidylcholine synthesis through the action of a predominantly microsomal acyltransferase appears to be a minor pathway. In the presence of several acyl-CoAs, reutilization of lysophosphatidylcholine is significantly increased by an acyl-CoA:lysophosphatidylcholine acyltransferase (EC 2.3.1.23) but there is no preferential transfer of arachidonyl-CoA compared to other acyl-CoAs.
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PMID:Phospholipid metabolism in the rat renal inner medulla. 661 66

The effects of membrane sterol level on the susceptibility of LM cell plasma membranes to exogenous phospholipases A2 has been investigated. Isolated plasma membranes, containing normal or decreased sterol content, were prepared from mutant LM cell sterol auxotrophs. beta-Bungarotoxin-catalyzed hydrolysis of both endogenous phospholipids and phospholipids introduced into the membranes with beef liver phospholipid exchange proteins was monitored. In both cases, phosphatidylcholine (PC) and phosphatidylethanolamine (PE) were degraded at similar rates in normal membranes, while PC hydrolysis was specifically accelerated in sterol-depleted membranes. Additional data suggest that this preferential hydrolysis of PC is not a consequence of the phospholipid head group specificity of the phospholipase, nor of a difference in the accessibility of PC versus PE to the enzyme. Analysis of the reaction products formed during treatment of isolated membranes with phospholipase A2 showed almost no accumulation of lysophospholipids. This was found to be due to highly active lysophospholipase(s), present in LM cell plasma membranes, acting on the lysophospholipids formed by phospholipase A2 action. A soluble phospholipase A2 was partially purified from LM cells and found to behave as beta-bungarotoxin with regard to membrane sterol content. These results demonstrate that the nature of phospholipid hydrolysis, catalyzed by phospholipase A2, can be significantly affected by membrane lipid composition.
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PMID:Effect of membrane sterol content on the susceptibility of phospholipids to phospholipase A2. 661 38

The partial characterization of a calcium-dependent phospholipase A2 associated with membranes of mouse sperm is described. Intact and sonicated sperm had comparable phospholipase A2 activity which was maximal at pH 8.0 using [1-14C]oleate-labeled autoclaved Escherichia coli or 1-[1-14C]stearoyl-2-acyl-3-sn-glycerophosphorylethanolamine as substrates. More than 90% of the activity was sedimented when the sperm sonicate was centrifuged at 100 000 X g, indicating that the enzyme is almost totally membrane-associated. The activity is stimulated 200% during the ionophore-induced acrosome reaction and is almost equally distributed between plasma/outer acrosomal and inner acrosomal membrane fractions. The membrane-associated phospholipase A2 had an absolute requirement for low concentrations of Ca2+; Sr2+, Mg2+ and other divalent and monovalent cations would not substitute for Ca2+. In the presence of optimal Ca2+, zinc and gold ions inhibited the activity while Cu2+ and Cd2+ were without effect. Incubation of sperm sonicates with 1-[1-14C]stearoyl-2-acyl-3-sn-glycerophosphorylethanolamine in the presence and absence of sodium deoxycholate demonstrated the presence of phospholipase A2 and lysophospholipase activities. No phospholipase A1 activity was detectable. Indomethacin, sodium meclofenamate and mepacrine, but not dexamethasone or aspirin, inhibited the sperm phospholipase A2 activity. Preincubation with p-bromophenacyl bromide inhibited phospholipase A2, suggesting the presence of histidine at the active site. The enzyme may play an important role in the membrane fusion events in fertilization.
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PMID:Surface-active phospholipase A2 in mouse spermatozoa. 662 66

Lysophospholipase (EC 3.1.1.5) and phospholipase A2 (EC 3.1.1.4) were determined in ileal mucosa from patients with Crohn's disease (CD) and non-inflammatory bowel diseases ( NIBD ). In addition, the activities of alkaline phosphatase, sucrase, maltase, and lactase were determined. The lysophospholipase activity, like that of alkaline phosphatase, sucrase and maltase, was decreased in affected areas of CD, whereas the phospholipase A2 activity was rather increased. Lysophospholipase and phospholipase A2 activities in apparently unaffected mucosa from CD patients were in between those in healthy mucosa from NIBD patients and those in affected mucosa from CD patients. These findings point to the possibility that the mucosal activity of lysophospholipase, like that of other brush border enzymes, is decreased in CD. This may render the mucosa less capable to handle lysolecithin, a potentially harmful agent formed in the intestine and known to induce inflammation in a number of experimental systems.
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PMID:Decreased lysophospholipase and increased phospholipase A2 activity in ileal mucosa from patients with Crohn's disease. 672 69

Phospholipase A2 and lysophospholipase activities were detected in the culture supernatant fluids of a virulent strain of Vibrio vulnificus. The phospholipase A2 was inactivated by heating at 56 degrees C for 30 min, had an apparent molecular weight of greater than or equal to 80,000 (estimated by gel filtration with Sephadex G-75), and a pI of ca. 5.0. Phospholipid hydrolysis was unaffected by Ca2+ or ethylene glycol-bis(beta-aminoethyl ether)-N,N-tetraacetic acid and was optimal at pH 5.0 to 5.5. The lysophospholipase was not affected by heating at 56 degrees C for 30 min but was inactivated at 100 degrees C and had an apparent molecular weight of greater than or equal to 80,000 and a pI of ca. 4.0. The enzymes were detected coincidentally with a previously described extracellular cytolysin of V. vulnificus; however, they were physically separable from the toxin (which did not possess phospholipase A, C, or D activity) by gel filtration with Sephadex G-75.
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PMID:Extracellular phospholipase A2 and lysophospholipase produced by Vibrio vulnificus. 674


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