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)

Aerolysin, a hemolytic and lethal exotoxin of Aeromonas hydrophila, was analyzed for amino acids. Assuming 8 histidine residues/mol, the purified toxic protein has, by summation, a molecular weight of 49,000, a value in agreement with earlier estimates by other methods. Erythrocytes from different animal species differ greatly in sensitivity to aerolysin's lytic action. There is some correlation between sensitivity and phosphatidyl choline content. Erythrocyte membranes of different species bind the toxin, and the efficiency of binding is a function of sensitivity to lysis. Binding is temperature independent, is not dependent upon membrane sialic acid, and is decreased by prior treatment with phospholipase C and proteases. Preparations of aerolysin convert substantial amounts of membrane phosphorus to water-soluble form; the conversion is concentration and temperature dependent. Most of the conversion is attributable to contaminating phospholipase(s) that is separable from the toxin. Aerolysin purified by electrophoresis in polyacrylamide gel retains some phospholipase activity, and this activity may or may not be a contaminant.
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PMID:Interactions between aerolysin, erythrocytes, and erythrocyte membranes. 16 17

A threonine phospholipid in polyoma virus-transformed hamster embryo fibroblasts has been characterized as phosphatidylthreonine. The identification has been made by chemical and enzymatic hydrolysis. Acid hydrolysis of the phospholipid produces free threonine. Mild alcoholysis produces a water-soluble derivative having the properties of glycerophosphorylthreonine. Hydrolysis with phospholipase C produces phosphorylthreonine which on prolonged acid hydrolysis yields threonine. Phosphatidylthreonine in the cell is more accessible to reaction with fluorodinitrobenzene than is phosphatidylserine. Phosphatidylthreonine also has been found as a major aminophospholipid in two other polyoma-transformed hamster cell lines and in the BHK-21/C13 line including the PVT-3 and TS-3 lines. the latter derived from BHK cells. Only a trace amount of phosphatidylthreonine occurs in normal liver, kidney and spleen of the adult mouse, in normal liver and kidney of the adult hamster, in whole mouse and hamster embryos, and in mouse 3T3 cells and SV40-transformed 3T3 cells.
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PMID:Characterization of phosphatidylthreonine in polyoma virus transformed fibroblasts. 20 23

The fluorescent probes 8-anilino-1-naphthalenesulfonate (ANS) and 2-p-toluidinylnaphthalene-6-sulfonate (TNS) bind to highly purified myelin membranes obtained from bovine brain white matter. Binding of the dyes was markedly increased by environmental conditions which reduce the negative surface potential of the membrane, i.e., cations (La-3+ is greater than Ca-2+ is greater than Na-+,K-+), H-+, local anesthetics, and the antibiotic polymyxin B. Chemical alteration of accessible membrane charged groups affected dye binding in a manner consistent with the hypothesis that such binding is primarily dependent upon the membrane surface potential. Thus, binding was increased by blocking of carboxyl groups via carbodiimide activation and subsequent coupling with neutral amino acid esters, and even more so with a basic amino acid ester (e.g., arginine methyl ester). Dye binding was reduced by succinylation of amino groups, and by hydrolysis of choline and ethanolamine head groups of phospho- and sphingolipids by phospholipase C. Phospholipase C treatment of myelin, or sphingomyelin vesicles, reduced or abolished the augmentation of ANS and TNS binding due to cations, local anesthetics, or polymyxin B. Energy transfer from myelin tryptophan residues to bound ANS occurs, but with low efficiency. Oxidation of membrane tryptophan residues with N-bromosuccinimide, or alkylation with 2-hydroxy (or methoxy)-5-nitrobenzyl bromide, markedly reduced intrinsic membrane fluorescence and energy transfer to bound ANS, but did not significantly affect dye binding or the quantum yield of ANS fluorescence when excitation was at 380nm. Proteolytic digestion removed 6-30% of myelin protein, depending upon the enzyme used, but had no effect on fluorescent dye binding. It is concluded that the binding of the anionic fluorescent probes ANS and TNS to myelin is primarily a function of the membrane surface charge density and net surface potential, as is the case with other biological membranes. Conclusions about the degree of dye binding to membrane lipids or membrane proteins cannot be drawn unless additional studies are carried out on isolated water soluble membrane proteins.
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PMID:Reactions of fluorescent probes with normal and chemically modified myelin. 23 81

We report here the inhibition of enzyme activity of phospholipase C-anti-human rabbit IgG conjugate complexed with human IgG. Phospholipase C activity was measured by assaying the release of hemoglobin from erythrocytes. The degree of inhibition varies depending on the relative amount of IgG utilized. A water soluble carbodiimide linking yields a conjugate which is inhibited by IgG, while conjugate prepared by glutaraldehyde is not. Immunodiagnostic assays requiring detection of low levels of antigen or antibody may be possible utilizing the phospholipase C-erythrocyte technique.
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PMID:Phospholipase C-labeled anti-human IgG: inhibition by human IgF. 32 66

Phospholipase C from Bacillus cereus was inactivated by incubation with either of the carboxyl reagents, a water-soluble carbodimide plus a nucleophile or Woodward's reagent K. With the former reagent, the incorporation into the enzyme of the first mol of nucleophile caused a 4-5-fold increase in the Km for dihexanoyllecithin with no significant effect on the Vm. The second mol of nucleophile incorporated caused no further change in Km but destroyed most of the catalytic activity. Modification of the enzyme by carbodiimide plus nucleophile did not alter the relative activity of the enzyme towards micelles and monomolecularly dispersed solutions of diheptanoyllecithin. Furthermore, inactivation by this reagent did not significantly decrease the ability of the enzyme to bind to a substrate-based affinity gel. It was concluded that phospholipase C contains a single carboxyl group that is essential for catalytic activity. The enzyme also contains a total of 4-5 reactive/exposed carboxyl groups.
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PMID:Inactivation of phospholipase C from Bacillus cereus by a carboxyl group modifying reagent. 40 15

(1) The hydrolysis of (32)P- or myo-[2-(3)H]inositol-labelled rat liver microsomal phospholipids by rat liver lysosomal enzymes has been studied. (2) The relative rates of hydrolysis of phospholipids at pH4.5 are: sphingomyelin>phosphatidylethanolamine>phosphatidylcholine> phosphatidylinositol. (3) The predominant products of phosphatidylcholine and phosphatidylethanolamine hydrolysis are their corresponding lyso-compounds, indicating a slow rate of total deacylation. (4) Ca(2+) inhibits the hydrolysis of all phospholipids, though only appreciably at high (>5mm) concentration. The hydrolysis of sphingomyelin is considerably less sensitive to Ca(2+) than that of glycerophospholipids. (5) Analysis of the water-soluble products of phosphatidylinositol hydrolysis (by using myo-[(3)H]inositol-labelled microsomal fraction as a substrate) produced evidence that more than 95% of the product is phosphoinositol, which was derived by direct cleavage from phosphatidylinositol, rather than by hydrolysis of glycerophosphoinositol. (6) This production of phosphoinositol, allied with negligible lysophosphatidylinositol formation and a detectable accumulation of diacylglycerol, indicates that lysosomes hydrolyse membrane phosphatidylinositol almost exclusively in a phospholipase C-like manner. (7) Comparisons are drawn between the hydrolysis by lysosomal enzymes of membrane substrates and that of pure phospholipid substrates, and also the possible role of phosphatidylinositol-specific lysosomal phospholipase C in cellular phosphatidylinositol catabolism is discussed.
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PMID:Hydrolysis of membrane phospholipids by phospholipases of rat liver lysosomes. 50 1

Photoreceptor membranes derived from isolated bovine rod outer segments, are subjected to treatment with phospholipase C (Bacillus cereus). This results in varying degrees of hydrolysis of the membrane phospholipids into diglycerides and water soluble phosphate esters without loss of rhodopsin. Electron microscopic observations of thin sections and freeze-fractured preparations indicate extrusion of diglycerides from the membranes and their coalescence to lipid droplets, beginning at 20% hydrolysis of phospholipids. After 90% hydrolysis of phospholipids membranous structures are still present. The rhodopsin is located in these structures, presumably in the form of two-dimensional lateral aggregates. This explains the cross-fracturing of the membranous structures, regularly observed upon freeze-fracturing of the phospholipase-treated photoreceptor membranes.
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PMID:Biochemical aspects of the visual process. XXXVII. Evidence for lateral aggregation of rhodopsin molecules in phospholipase C-treated bovine photoreceptor membranes. 64 3

A 247 000 x g particulate fraction from a moderately halophilic halotolerant bacterium incorporated [14C] glucose added as UDP[14C]glucose and 32P-labeled phosphatidylglycerol into glucosylphosphatidylglycerol. Exogenously added phosphatidylglycerol was available to the enzyme only when dispersed in a detergent, preferably Triton X-405, by sonication. The 14C- or 32P-labeled glucosylphosphatidylglycerol was degraded with phospholipase C. The water soluble product formed was isolated and identified by paper chromatography as glucosylglycerolphosphate. The system required Mg2+ or Ca2+ for activity. KCl and NaCl were inhibitory even when added at low concentrations.
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PMID:Glycolipids of a halotolerant, moderately halophilic bacterium. 69 36

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


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