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:3.1.4.3 (phospholipase C)
18,461 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

[3-H]Epinephrine binding to isolated purified rat liver plasma membranes is a reversible process. An initial peak in binding occurs at about 15 min and a plateau occurs by 50 min. Optimal binding occurred at a membrane protein concentration of 125mug. Rat liver plasma membranes stored at-70 degrees C up to 4 weeks showed no difference in epinephrine binding capacity as compared to control fresh membranes. Epinephrine binding to liver plasma membranes was decreased by 79% by phospholipase A2 (phosphatide acylhydrolase EC 3.1.1.4), 81% by phospholipase C (phosphatidylcholine choline phosphohydrolase EC 3.1.4.3) and 59% by phospholipase D (phosphatidylcholine phosphatidohydrolase EC 3.1.4.4). Trypsin and pronase digestion of the membrane decreased epinephrine binding by 97 and 47% respectively. In the presence of 10-3M Mg-2+ ions, increasing concentrations of QTP decreased epinephrine binding to liver plasma membranes. A maximal effect was demonstrated with 10-5M GTP, representing an inhibition of 52% of the control. In a Mg-2+ -free system, epinephrine binding was unaffected by GTP. However, in a Mg-2+ -free system, increasing concentrations of ATP cause increasing inhibition of hormone binding. ATP at 10-3 M reduced epinephrine binding to 28% of the control. GRP (10-5 M) was shown to inhibit epinephrine uptake rather than epinephrine release from the membrane. [3-H]Epinephrine binding to isolated rat epididymal fat cells shows an initial peak within 5 min followed by a gradual rise which plateaus after 60 min. Epinephrine binding increased nearly linearly with increasing fat cell protein concentration (40-200 mug protein). GTP (10-5 M) and ATP (10-4 M) decreased epinephrine binding to rat epididymal fat cells by 41%. Nearly complete inhibition of binding was demonstrated with 10-2-10-3M ATP. Epinephrine analogs that contain two hydroxyl groups in the 3 and 4 position on the benzene ring act as inhibitors of [3-H]epinephrine binding to rat adipocytes. Alteration of the epinephrine side chain has relatively little influence on binding. Analogs in which one of the ring hydroxyl groups is missing or methylated are poor inhibitors of [3-H]epinephrine binding. Alpha-(phentolamine and phenoxybenzamine) and beta-(propranolol and dichorisoproterenol) adrenergic blocking agents were tested with respect to their ability to influence [3-H]epinephrine binding and their influence on epinephrine-stimulated lipolysis. Only dichloroisoproterenol significantly inhibited epinephrine binding (by 25%). The two beta-adrenergic blocking agents caused an inhibition of epinephrine-stimulated glycerol release, with propranolol being most effective. Phentolamine and phenoxybenzamine had no significant effect on the epinephrine stimulation of glycerol release by fat cells.
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PMID:Hormone action at the membrane level. IV. Epinephrine binding to rat liver plasma membranes and rat epididymal fat cells. 16 9

In the presence of CMP, cholinephosphotransferase of mouse lung microsomes catalyzes the conversion of endogenous phosphatidylcholines into 1,2-diacyl-sn-glycerols and CDPcholine. 2. In this conversion cholinephosphotransferase shows a distinct preference for those molecular species of phosphatidylcholine which contain an unsaturated fatty acid. The enzyme hardly utilizes endogenous depalmitoylglycerophosphocholine as a substrate. 3. Membrane-bound 1,2-diacyl-sn-glycerols were also prepared by treatment of mouse lung microsomes with a pure phospholipase C from Bacillus cereus. These 1,2-diacyl-sn-glycerols were subsequently utilized as substrate by cholinephosphotransferase in the formation of phosphatidylcholine. In the latter reaction, cholinephosphotransferase exhibited a pronounced preference for unsaturated 1,2-diacyl-sn-glycerols and hardly utilized the endogenous 1,2-depalmitoyl-sn-glycerol. 4. The low affinity of cholinephosphotransferase for either dipalmitoylglycerophosphocholine or 1,2-dip
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PMID:Selective utilization of endogenous unsaturated phosphatidylcholines and diacylglycerols by cholinephosphotransferase of mouse lung microsomes. 18 25

The spin-labeled cardiolipin 1-(3-sn-phosphatidyl)-3-[1-acyl-2-(16-doxylstearoyl)glycero(3)phosphol]-sn-glycerol has been prepared. The stereoselective synthesis makes use of the monolysocardiolipin 1-(3-sn-phosphatidyl)-3-[1-acyl-2-lyso-sn-glycero(3)phospho]-sn-glycerol, available from the stereospecific hydrolysis of cardiolipin by phospholipase A2 (phosphatide 2-acylhydrolase, EC 3.1.1.4) of Trimeresurus flavoviridis. The results of treatment of the spin-labeled cardiolipin with the cardiolipin-specific phospholipase D (phosphatidylcholine phosphatidohydrolase, EC 3.1.4.4) (Hemophilus parainfluenzae) of known specificity and with phospholipase C (phosphatidylcholine cholinephosphohydrolase, EC 3.1.4.3) of Bacillus cereus are consistent with the assigned structure. The spin-labeled cardiolipin is further characterized and the unique features of this diastereomer are discussed in the context of the unusual stereochemistry of the natural phospholipid.
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PMID:Cardiolipin: a stereospecifically spin-labeled analogue and its specific enzymic hydrolysis. 27 15

Erythrocytes from several different species were exposed to Ca2+ and the bivalent-cation ionophore A23187. The lipid composition, morphology and K+ permeability of the treated cells were investigated. Erythrocytes from human, rat, guinea pig and rabbit (a) showed an increased concentration of 1,2-diacyl-sn-glycerol and enhanced labelling of phosphatidate with 32P, (b) underwent echinocytosis and outward vesiculation, and (c) rapidly released much of their intracellular K+. Pig cells showed only the K+ loss, and ox and sheep (high-K+) cells showed none of these Ca2+-evoked effects. All of the cells underwent stomatocytosis and inward vesiculation when treated externally with Clostridium perfringens phospholipase C. These results support the idea that there is a correlation between the asymmetric insertion of diacylglycerol (or ceramide) into the membrane and the shape-changes leading to microvesiculation, but they indicate that Ca2+-triggered K+ efflux and diacylglycerol production are unrelated events. Erythrocytes of chicken and turkey showed no Ca2+-stimulated K+ efflux. They showed slight ionophore A23187-stimulated vesiculation, but this appeared to be associated with the appearance in the membrane of ceramide rather than of diacylglycerol. Phospholipase C treatment caused very similar changes in morphology and phosphatidate labelling to those seen in mammalian erythrocytes.
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PMID:Calcium ion-dependent diacylglycerol accumulation in erythrocytes is associated with microvesiculation but not with efflux of potassium ions. 33 8

Didansyl derivatives of amino acids and N-phenyl-1-naphthylamine were used to localize membrane hydrophobic sites in glycerol-extracted chicken skeletal muscle fibers. Epifluorescence microscopy revealed that such sites coincide with the distribution of mitochondria, the transverse tubular (T) system and the sarcoplasmic reticulum (SR). They are specifically associated with myofibril Z lines and occasionally extend from one Z plane to the next longitudinally along the muscle fiber. The hydrophobic probes interact noncovalently with the Z lines, and their induced fluorescence can be eliminated by exposure of the myofibrils to ionic detergents, nonionic detergents, or phospholipase C, before or after addition of the hydrophobic label. Extraction of glycerinated fibers with 0.6 M KI removes the majority of sarcomeric actin and myosin and leaves a scaffold of longitudinally interconnected Z planes. Membrane fluorescence remains tightly associated with these Z planes and with the remnant mitochondria. Shearing of such scaffolds results in the cleavage of the longitudinal connections and the production of large sheets of interconnected, close-packed Z discs in a honeycomb-like array. Comparison of the localization of two Z disc proteins, desmin and alpha-actinin, with that of the membrane material reveals that alpha-actinin is localized in the interior of each myofibril Z disc whereas both desmin and the membrane material surround each disc. Thus, glycerination and KI extraction of muscle fibers leaves remnants of T system and SR membranes tightly associated with the Z disc honeycomb lattice. Because the Z discs are connected at their peripheries through the T system appear to the plasma membrane, desmin and this membrane structure appear to be connected throughout the whole Z plane up to and including the plasma membrane. The congruent localization of desmin and the T system strongly suggests that this molecule mediates the adhesion of this membrane system around each Z disc.
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PMID:Fluorescent localization of membrane sites in glycerinated chicken skeletal muscle fibers and the relationship of these sites to the protein composition of the Z disc. 35 93

A new colorimetric determination for serum phospholipid is described. Firstly, serum phospholipid is incubated with phospholipase C from Bacillus cereus, and then the released diglyceride and triglyceride are hydrolyzed completely to fatty acid and glycerol by lipoprotein lipase from Pseudomonas fluorescens. Secondly, the glycerol produced is enzymatically determined by glycerol dehydrogenase in the presence of NAD+, using phenazine methosulfate-nitro blue tetrazolium as color reagents. The absorbance at 570 nm is recorded. The amount of the glycerol from phospholipid is calculated by subtracting the amount of glycerol from triglyceride from the amount of total glycerol. The present method requires only 20 microliter of serum and a 40 min incubation and is highly reproducible. The results obtained show good correlation with those obtained by a chemical method (correlation coefficient, 0.925) or the phospholipase D-choline oxidase method (correlation coefficient, 0.936). These results strongly suggest that the proposed method can be utilized as a routine clinical test.
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PMID:An enzymic determination for serum phospholipid. 70 86

A method is described for the isolation of CDP-diglyceride from bovine brain. Yields of the product ranged from 9.2-15.5 mumol per kilogram of tissue, which corresponds to about 1% of the level of phosphatidic acid. Mild alkaline hydrolysis of the product gave three water-soluble phosphate esters which had the same electrophoretic mobilities as CMP, CDP-glycerol and glycerol 3-phosphate. The liponucleotide was quantitatively hydrolysed by CDP-diglyceride hydrolase from Escherichia coli to phosphatidic acid and CMP. No dCMP was recovered in enzymatic or alkaline hydrolysates and it is concluded there can be little or no dCDP-diglyceride in bovine brain. Brain CDP-diglyceride was similar to phosphatidylinositol in that in both lipids stearate was the major saturated fatty acid and arachidonate the most abundant unsaturated fatty acid. This differed significantly from the fatty acid patterns of other metabolically related phospholipids, phosphatidic acid and cardiolipin. Brain CDP-diglyceride was hydrolysed with phospholipase C from Clostridium welchii with the liberation of the diglyceride moiety in high yield. Treatment of the diglyceride with pancreatic lipase showed CDP-diglyceride with the asymmetric distribution of fatty acids characteristic of most mammalian phospholipids, saturated fatty acids being found mostly at position 1 and polyunsaturated fatty acids at position 2. The derived diglyceride acetates were separated into different molecular species by argentation thin-layer chromatography. These analyses showed that 1-stearoyl, 2-arachidonoyl was the major species of brain CDP-diglyceride.
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PMID:Cytidine diphosphate diglyceride of bovine brain. Positional distribution of fatty acids and analysis of major molecular species. 77 22

3,4-Dihydroxy[3-(3)H]butyl-1-phosphonate, and analogue of glycerol 3-phosphate, is incorporated into a very polar lipid material by cultures of Escherichia coli strain 8 and in vitro by CDP-diglyceride:sn-glycerol-3-phosphate phosphatidyltransferase. These labeled lipids have been fractionated by column chromatography on DEAE-cellulose, revealing that only one labeled compound is formed in vitro, while four are synthesized in vivo. The main component of the material formed by intact cells has been shown to be identical with that produced enzymatically. This species has been identified as the phosphonic acid analogue of phosphatidylglycerophosphate [(1,2-diacyl)-sn-glyceryl-D-4'-phosphoryloxy-3'-hydroxybutyl-1'-phosphonate]. Hydrolysis of this novel lipid with phospholipase C resulted in the production of diglyceride and a water-soluble derivative of 3,4-dihydroxybutyl-1-phosphonate and inorganic phosphate in a molar ratio of 1.03/1. Enzymatic analysis of the phosphonate liberated in this manner showed it to be the D enantiomer, thereby confirming the proposed structure of the lipid analogue. The analogue of phosphatidylglycerophosphate did not turn over and appeared to have no precursor-product relationship to the other labeled lipids derived from 3,4-dihydroxy[3-(3)H]butyl-1-phosphonate in vivo. Analysis of the other three labeled products revealed the tritium to be present on glycerol 3-phosphate and not intact phosphonate, indicating some metabolic degradation of the latter. Examination of cell components other than lipids revealed little incorporation of label, while a significant amount of tritium was found to be present in a distillable form, 3H2O. Experiments with mutants of E. coli lacking the known glycerol-3-phosphate dehydrogenases indicated that these enzymes are not responsible for the removal of tritium from from 3,4-dihydroxy[3-(3)H]butyl-1-phosphonate in vivo. Indirect evidence suggests that the inhibition of cell growth by this analogue is not due to its catabolic products.
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PMID:Metabolic fate of 3,4-dihydroxybutyl-1-phosphonate in Escherichia coli. 78 74

The effects of lipoprotein lipase, phospholipase A2 and phospholipase C on chylomicron phosphatidylcholine and triacylglycerol were studied with rat lymph chylomicrons containing phosphatidylcholine labeled with [14C]oleic acid. Lipoprotein lipase purified from bovine milk readily hydrolyzed chylomicron phosphatidylcholine to lysophosphatidylcholine and fatty acid, and triacylglycerol to monoacylglycerol, fatty acid and glycerol. The rates of hydrolysis of phosphatidylcholine and triacylglycerol increased with enzyme concentration, and both decreased when fatty-acid binding sites on albumin in the incubation medium were limited. The proportion and amount of phosphatidylcholine hydrolyzed was always less than that of triacylglycerol. Analyses of hydrolytic products showed that lipoprotein lipase cleaved the 1-acyl ester bond of phosphatidylcholine. The findings indicate that lipoprotein lipase can account for some of the phospholipase A1 activity found in postheparin plasma. Phospholipase A2 and phospholipase C hydrolyzed chylomicron phosphatidylcholine, greater than 92% in 10 min, but not triacylglycerol. The resultant phosphatidylcholine-deficient chylomicrons, which could be concentrated by ultra-centrifugation and resuspended in incubation medium, were readily depleted of triacylglycerol when incubated with lipoprotein lipase. The findings indicate that phosphatidylcholine can be removed from the surface film of chylomicrons without disrupting the particles or blocking the action of lipoprotein lipase on the core triacylglycerol.
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PMID:Hydrolysis of chylomicron phosphatidylcholine in vitro by lipoprotein lipase, phospholipase A2 and phospholipase C. 94 90

A simple method is reported for the determination of GPL in serum, requiring small amount of sample and adequate for screening of large population groups. The method is based on the release of glycerol portion of the phospholipid molecule by the combined action of phospholipase C and lipase. The glycerol is then determined by well established methods. The importance of screening of lecithin, that accounts for more than 84% of the glycerophospholipids of serum lipoproteins, is discussed in view of lipoprotein function and structure and in view of interaction between lipoproteins and plasma membranes.
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PMID:A completely enzymatic method for the determination of glycerophospholipids in human serum. 102 16


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