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)

Crude mitochondrial preparations from Neurospora crassa contain high levels of lysophospholipase (EC 3.1.1.5) activity when assayed with lysophosphatidylcholine as a substrate. In mitochondria purified by centrifugation on a sucrose-density gradient this activity is virtually absent. The enzyme was shown to be linked to a contaminating cell fraction which mainly consists of cell-wall material as was demonstrated by electron microscopy and chemical analysis. The enzyme has no absolute Ca2+ requirement but it is slightly stimulated by 10 mM CaCl2. The pH optimum is 5.8 in presence of CaCl2 and is shifted to 4.2 when EDTA is present. In contrast to other lysophospholipases this enzyme is only slightly inhibited by deoxycholate. This detergent is able to release part of the lysophospholipase activity from the wall fragments without producing an increase in specific activity. The enzyme is possibly secreted by the cells as high lysophospholipase activities were also found in the culture medium.
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PMID:Lysophospholipase activity in cell-wall fragments contaminating mitochondrial fractions of Neurospora crassa. 0 19

1. Phospholipase B which hydrolyzes both the acyl ester bonds of diacylphospholipids (diacyl-hydrolase) and the acyl ester bond of monoacylphospholipids or lysophospholipids, [monoacyl-hydrolase or lysophospholipase, EC 3.1.1.5] was purified from Penicillium notatum about 2000-fold over the crude extract. The final preparation was homogeneous on disc electrophoresis. The apparent molecular weight, determined by gel filtration on Sephadex G-200, was about 116,000. The isoelectric point was pH 4.0. 2. The purified enzyme was a glycoprotein. The carbohydrate content was approximately 30%, consisting of mannose, glucose, and glucosamine. The amino acid composition was also determined. 3. The ratio of monoacyl-hydrolase to diacyl-hydrolase activities was influenced by the physical state of the substrate in the assay system. It was about 1 : 1 or 100 : 1 in the presence of absence of Triton X-100, respectively, and the latter value remained constant throughout the purification procedures. 4. Both enzyme activities had the same pH optimum, 4.0, and were heat-labile. None of the metals tested had any effect on either activity except for Fe2+ and Fe3+. Diisopropyl fluorophosphate at relatively high concentrations completely inhibited both enzyme activities. 5. The Michaelis-Menten constants (Km) of the enzyme for egg lecithin were about 1.5 and 25 mM in the absence and presence of Triton X-100, respectively. The Km value for dicaproyllecithin was 9.8 mM in the absence of Triton X-100. 6. Using a mixture of 1-[14C]stearoyl-lecithin and 2-[14C]oleoyl-lecithin in the presence of Triton X-100 as a substrate, it was found that the P. notatum phospholipase B attacked the acyl ester bonds sequentially, first the 2-acyl and then 1-acyl groups.
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PMID:Studies on a phospholipase B from Penicillium notatum. Purification, properties, and mode of action. 0 2

Hydrolysis of 1-lysolecithin (1-acyl glycerophosphorylcholine [1-acyl GPC]) by preparations of phospholipase D from peanut seeds was investigated. 1-Lysolecithin was hydrolyzed at a much slower rate than phosphatidylcholine (lecithin). Although Ca+2 ions are required for the cleavage of lecithin by the enzyme, their effect on the hydrolysis of lysolecithin depended upon the concentration of the substrate: at 0.2 mM 1-lysolecithin, Ca+2 ions increased the reaction rates, whereas at concentrations of the substrate lower than 0.1 mM, Ca+2 ions were inhibitory. A broad pH activity curve between 5 and 8 was obtained with higher rates in the alkaline range, both in the absence and presence of Ca+2 ions. The increased hydrolysis of lysolecithin due to Ca+2 was noticed over the entire pH range. Upon storage of the enzyme solutions at 4 C, decreased rates of hydrolysis of lecithin were observed, with t 1/2 values of ca. 50 and 100 days depending on the purity of the preparation. During the same period, no reduction occurred in the activity of these preparations on lysolecithin as substrate. The effects of Ca+2 ions and the analysis of the products of 1-acyl GPC cleavage by the enzyme preparations revealed the presence of more than one enzyme and the formation of the following compounds: lysophosphatidic acids (1 acyl glycerophosphoric acids), free fatty acids, glycerophosphorylcholine, and choline. The possible pathways leading to the degradation of lysolecithin and the formation of these products include reactions catalyzed by lysophospholipase A1 (lysophosphatidylcholine 1-acyl hydrolase, E.C. 3.1.1.5) and a phosphodiesterase (L-3-glycerylphosphorylcholine glycerophosphohydrolase, E.C.3.1.4.2), in addition to phospholipase D (phosphatidyl-choline phosphatidohydrolase, E.C. 3.1.4.4).
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PMID:Enzymatic hydrolysis of 1-monoacyl-SN-glycerol-3-phosphoryl-choline (1-lysolecithin) by phospholipases from peanut seeds. 0 56

Phospholipase A1, A2 and lysophospholipase activities in microsomes of Novikoff hepatoma host rat liver and regenerating rat liver were compared using 1-[9', 10'-3H2]palmitoyl-2-[1'-14C] linoleoyl-sn-glycero-3-phosphoethanolamine, 1-[1' -3H-]hexadecyl-2-acyl-sn-glycero-3-phosphoethanolamine, and 1-[9', 10'-3H2]palmitoyl-sn-glycero-3-phosphoethanolamine as substrates. 1. Microsomes of all three tissues showed two pH dependent peaks of hydrolytic activity, one at pH 7.5 and another at pH 9.5. 2. Phospholipid hydrolytic activity in microsomes from host liver and regenerating liver require Ca2+ for hydrolysis at pH 9.5, but not at pH 7.5. Hepatoma microsomes require Ca2+ for activity at both pH values. 3. Phospholipase A1 activity, stimulated by addition of Triton X-100 to the incubation mixtures, was detected in both host liver and regenerating liver microsomes. There was no evidence of phospholipase A1 activity in hepatoma microsomes. 4. Phospholipase A2 was detected in microsomes of all three tissues using 1-[1'-3H] hexadecyl-2-acyl-sn-glycero-3-phosphoethanolamine as a substrate. The activity required calcium and was inhibited by Triton X-100. 5. Lysophospholipase activity was evident in the microsomes from all three tissues. The activity was inhibited by both Ca2+ and Triton X-100. 6. Differences were also detected between host liver and hepatoma microsomal phospholipid hydrolase activities with respect to the effect of increasing protein concentration, apparent Michaelis-Menten constants, and time course of the reaction.
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PMID:Properties of microsomal phospholipases in rat liver and hepatoma. 1 Sep 88

Detergent-resistant phospholipase A, which is tightly bound to the outer membranes of Escherichia coli K-12 cells, was purified approximately 2000-fold to near homogeneity by solubilization with sodium dodecylsulfate and butan-1-ol, acid precipitation, acetone fractionation and column chromatographies on Sephadex G-100 in the presence of sodium dodecylsulfate and on DEAE-cellulose in the presence of Triton X-100. The final preparation showed a single band in the sodium dodecylsulfate gel system. The enzyme hydrolyzes both the 1-acyl and 2-acyl chains of phosphatidylethanolamine or phosphatidylcholine. It also attacks 1-acyl and 2-acylglycerylphosphorylethanolamine. Thus, this enzyme shows not only phospholipase A1 and lysophospholipase L1 activities but also phospholipase A2 and lysophospholipase L2 activities. The enzyme lost its activity completely on incubation at 80 degrees C for 5 min at either pH 6.4 or pH 8.0. It was stable in 0.5% sodium dodecylsulfate at below 40 degrees C. The enzyme was inactivated on incubation for 5 min at 90 degrees C in 1% sodium dodecylsulfate/1% 2-mercaptoethanol/4 M urea. The native and inactivated enzymes showed different protein bands with RF values corresponding to Mr 21 000 and Mr 28 000 respectively, in a sodium dodecylsulfate gel system. Triton X-100 seemed to protect the enzyme from inactivation. The purified enzyme was fully active on phosphatidylethanolamine in the presence of 0.0002% or 0.05% Triton X-100. The enzyme requires Ca2+. From its properties this enzyme seems to be identical with the enzyme purified from crude extracts of Escherichia coli B by Scandella and Kornberg. However, it differs from the latter in its positional specificity and susceptibility to sodium dodecylsulfate. Possible explanation of the difference of positional specificity of the two preparations is also described.
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PMID:Detergent-resistant phospholipase A of Escherichia coli K-12. Purification and properties. 1 2

1.1. Lysosome-enriched fractions were prepared by differential centrifugation of homogenates of luteinized rats ovaries. Acid phospholipase A activities were characterized with [U-14C]diacyl-sn-glycero-3-phosphocholine and 1-palmitoyl-2-[9,10-3H]- or [1-14C]oleoyl-sn-glycero-3-phosphocholine as substrates. Acid phospholipase A1 activity had properties similar to other hydrolases of lysosomal origin; subcellular distribution, latency and acidic pH optimum. Acid phospholipase A2 activity with similar characteristics was also tentatively identified. We were unable to exclude the possibility that the combined action of phospholipase A1 and lysophospholipase contributed to the release of acyl moieties from the 2-position of the synthetic substrates. 2. Lysophospholipase activity was present in the lysosome-enriched fractions. This activity had an alkaline pH optimum. 3. Phospholipase A1 and A2 activities solubilized from lysosome fractions by freeze-thawing were inhibited by Ca2+ and slightly activated by EDTA. A Ca2+- stimulated phospholipase A2 activity, with an alkaline pH optimum, remained in the particulate residue of freeze-thawed lysosome preparations. This activity is believed to represent mitochondrial contamination. 4. Activities of acid phospholipase A, as well as other acid hydrolases, increased approx. 1.5-fold between 1 and 4 days following induction of luteinizatin, suggesting a hormonal influence on lysosomal enzyme activities.
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PMID:Lysosomal phospholipase A activities of rat ovarian tissue. 1 58

Rat pancreas presents a spontaneous phospholipase A activity which appears before trypsin activation at optimal pH 6.5. The responsible enzyme is independent of pancreatic prophospholipase A, as can be seen through experiments done in the presence of trypsin inhibitors. On the other hand, this enzyme is distinct from excretory phospholipase which is more active and whose optimal pH is 8.8. Thermostability and insensibility of spontaneously active phospholipase A to DFP differentiate it from lipase, carboxyl-esterhydrolase and lysophospholipase, respectively.
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PMID:[Spontaneous phospholipase A activity of rat pancreatic homogenates]. 1 5

Phospholipase activities of rat intestinal mucosa homogenate have been determined from lysophosphatidylcholines [14C] and phosphatidylcholines [-3H-14C]. In the presence of phosphatidylcholines, at pH 6.5, the homogenate has a phospholipase B activity. At pH 8.5, a phospholipase A2 activity was shown. In the presence of lysophospatidylcholines, at pH 6.5, we notice a lysophospholipase A1 activity. A kinetic study of the reactions allows us to separate the activity B into a phospholipase A2 activity and a lysophospholipase A1 activity. Thus, it appears that the total phospholipase activity of rat intestinal mucosa would results from a phospholipase A2 activity and a lysophospholipase A1 activity.
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PMID:[Phospholipase of rat intestine: mode of action]. 1 16

Lysophospholipase [EC 3.1.1.5] was solubilized from the cells of Vibrio parahaemolyticus with Triton X-100 and purified by the following procedure; precipitation with ammonium sulfate, acid treatment and ion exchange column chromatography using DEAE-cellulose, DEAE-Sephadex A-50, and CM-cellulose, successively. The purified preparation was shown to be homogeneous by polyacrylamide gel disk electrophoresis. The isoelectric point of the enzyme was found to be around pH 3.64 by isoelectric focusing electrophoresis, and its molecular weight was estimated to be 89,000 at pH 7.6 by gel filtration on Sephadex G-200. The minimal molecular weight (15,000) was found at pH 3 by gel filtration on Sephadex G-100 and also by SDS-polyacrylamide disk electrophoresis. The enzyme hydrolyzed 1-acyl-GPC, 1-acyl-GPE, 2-acyl-GPE, and lysocardiolipin but did not attack monoacylglycerol, triacylglycerol, or phosphatidylcholine at all. The enzyme activity required no bivalent cations, and was unaffected by reagents specific to SH-groups, although it was inhibited by Hg2+. The enzyme activity was completely inhibited by preincubation with diisopropylfluorophosphate. The enzyme lost its activity on preincubation with either 1% SDS or 8 M urea at 37 degrees C for 30 min, but the activity lost with urea was recovered by dialysis against distilled water.
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PMID:Purification of lysophospholipase of Vibrio parahaemolyticus and its properties. 2 76

The positional specificity of the phospholipase A (EC 3.1.1.4) in human gallbladder epithelium has been studied using 14C-phosphatidylethanolamine radiolabeled either in the 1-acyl or in the 2-acyl position. After heating of homogenized epithelial cells at 70 degrees C for 2 min, their lysophospholipase activity was lost. In contrast, the ability to hydrolyze 14C-phosphatidylethanolamine in biosynthetically radiolabeled Escherichia coli was largely retained. The amounts of radioactivity found in the products of hydrolysis under different conditions suggest that there are two different phospholipase A activities in the gallbladder epithelium: one, with optimal activity at pH 7, that requires Ca2+ and is specific for the 2-acyl position, and another, with optimal activity at pH 4, that does not require Ca2+ and that, apart from the 2-acyl position, attacks the 1-acyl position as well. It is possible, therefore, that a complete deacylation of diacylphosphoglycerides in the gallbladder wall is brought about in two different ways: at neutral pH through a combined action of phospholipase A2 and lysophospholipase, the latter being able to hydrolyze the 1-acyl-lysophosphoglyceride, and, at acid pH, through the action of phospholipase A1 and A2 activity, presuming 1-acyl- and 2-acyl-lysophosphoglycerides are also attacked. Both these processes have to be considered in order to explain a turnover of diacylphosphoglycerides that physiologically would prevent the accumulation of lytic lysophosphoglycerides. The possible relevance of these findings to the pathogenesis of aseptic cholecystitis is inferred.
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PMID:The prerequisites for local lysolecithin formation in the human gallbladder. III. Demonstration of two different phospholipase A activities. 3 26


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