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)

Incubation of Rh positive ghosts with phospholipase A2 and C abolished the adsorption of Rh antibodies on the ghosts; incubation with phospholipase D, however, did not affect their adsorption and none of these phospholipases affected the adsorption of antibodies of the ABO system. The impairment of antigen-antibody-reaction in Rh positive ghosts treated with phospholipase corresponds to the absence of the antigen-antibody reaction with the membrane protein associated with Rh characteristics in the Schultz-Dale-Test. The chromatogram of the phospholipids extracted from those stromata treated with various phospholipases and those not treated showed different patterns. After incubation with phospholipase-A2 the lecithin and cephalin streaks were reduced and in addition lysophosphatide and fatty acid streaks were detected. In the case of phospholipase C the lecithin and cephalin streaks were further reduced while diglyceride streaks made their appearance. The phospholipid extracts from those stromata treated with phospholipase D and those not treated were identical. Phospholipase C reduced the values of lipid phosphorus more than did phospholipase A2, while phospholipase D did not reduce them at all. This study supports the results of other investigators who have postulated that the Rh antigens are located in a lipoprotein on the membrane of the human erythrocyte. The antigen-antibody-reaction seems to require a precise protein-phospholipid interaction.
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PMID:[The importance of phosphatidylcholine in the binding of anti-D to human erythrocyte ghost membrane (author's transl)]. 12 77

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

The pyruvate oxidase system of Escherichia coli is composed of a soluble flavoprotein, pyruvate oxidase (EC 1.2.2.2, pyruvate:ferricytochrome b1 oxidoreductase), and an electron transport system associated with the cell envelope-membrane fraction. The membrane particles contain 15% lipid by weight. Fractionation of the lipids revealed that abut one-third are neutral lipids and two-thirds are phospholipids. The relative ratio of ubiquinone to menaquinone within the neutral lipid fraction is 15:1 on a molar basis. Removal of the lipids from the membrane particles by extraction with aqueous acetone or hydrolysis of the phospholipids by treatment with Bacillus cereus phospholipase C results in a complete loss of electron transport activity. Analysis of the particles extracted with aqueous acetone revealed that practically all the neutral lipids and 65% of the phospholipids are removed by this treatment. Phospholipase treatment results in a loss of 75% of the membrane phospholipid phosphorus; however, the diglycerides and the neutral lipids produced by phospholipase hydrolysis remain associated with the particles. Addition of neutral lipid and a detergent, hepta-DL-alanyl dodecylamide to the acetone-extracted material results in a restoration of 37% of the original particle activity. Addition of neutral lipid and hepta-DL-alanyl dodecylamide to phospholipase-treated particles completely restores the original electron transport activity. Furthermore, addition of ubiquinone from either yeast (UQ6) or E. coli (UQ8) will restore pyruvate oxidase activity when the quinones are supplemented with photoinactivated neutral lipid. No restoration of activity to phospholipase-treated particles is noted upon the addition of either menaquinone 6 or menaquinone 8 to the reconstitution system. In fact, these compounds appear to suppress restoration of activity when they are added to reaction mixtures containing neutral lipid and phospholipase-treated particles.
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PMID:Reactivation of the lipid-depleted pyruvate oxidase system from Escherichia coli with cell envelope neutral lipids. 110 Jun 21

A lipid present in the granular cells of mammalian epidermis was identified as phosphatidyl-(N-acyl)-ethanolamine. The structure was deduced from the ratio of phosphorus : nitrogen : glycerol : fatty acid esters : total fatty acid (1 : 0.94 : 0.97 : 2.1 : 2.9), from analyses of the products of alkaline and acid hydrolyses and from its infrared spectrum. Conclusive evidence was obtained by a direct comparison of the chromatographic properties, degradation products and infrared spectrum of the isolated lipid with those of synthetic 1,2-dipalmitoyl-sn-glycero-3-phospho-(N-palmitoyl)-ethanolamine. The fatty acids attached to the ethanolamine were predominantly saturated (69% of total) and hexadecanoic acid was the major component (41% of total). Phosphatidyl-(N-acyl)-ethanolamine was hydrolysed by a phospholipase C (Bacillus cereus) to diacylglycerol, inorganic phosphorus and N-acylethanolamine. Evidence for the presence of N-acylethanolamine in granular cells and in stratum corneum suggested that an epidermal phospholipase C may be involved in the catabolism of phosphatidyl-(N-acyl)-ethanolamine.
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PMID:Phosphatidyl-(N-acyl)-ethanolamine. A lipid component of mammalian epidermis. 126 35

The phosphatidylinositol-specific phospholipase C (PI-PLC) from mammalian sources catalyzes the simultaneous formation of both inositol 1,2-cyclic phosphate (IcP) and inositol 1-phosphate (IP). It has not been established whether the two products are formed in sequential or parallel reactions, even though the latter has been favored in previous reports. This problem was investigated by using a stereochemical approach. Diastereomers of 1,2-dipalmitoyl-sn-glycero-3-(1D- [16O,17O]phosphoinositol) ([16O,17O]DPPI) and 1,2-dipalmitoyl-sn-glycero-3-(1D-thiophosphoinositol) (DPPsI) were synthesized, the latter with known configuration. Desulfurization of the DPPsI isomers of known configurations in H2(18)O gave [16O,18O]DPPI with known configurations, which allowed assignment of the configurations of [16O,17O]DPPI on the basis of 31P NMR analyses of silylated [16O,18O]DPPI and [16O,17O]DPPI (the inositol moiety was fully protected in this operation). (Rp)- and (Sp)-[16O,17O]DPPI were then converted into trans- and cis-[16O,17O]IcP, respectively, by PI-PLC from Bacillus cereus, which had been shown to proceed with inversion of configuration at phosphorus [Lin, G., Bennett, F. C., & Tsai, M.-D. (1990) Biochemistry 29, 2747-2757]. 31P NMR analysis was again used to differentiate the silylated products of the two isomers of IcP, which then permitted assignments of IcP with unknown configuration derived from transesterification of (Rp)- and (Sp)-[16O,17O]DPPI by bovine brain PI-PLC-beta 1. The results indicated inversion of configuration, in agreement with the steric course of the same reaction catalyzed by PI-PLCs from B. cereus and guinea pig uterus reported previously. For the steric course of the formation of inositol 1-phosphate catalyzed by PI-PLC, (Rp)- and (Sp)-[16O,17O]DPPI were hydrolyzed in H2(18)O to afford 1-[16O,17O,18O]IP, which was then converted to IcP chemically and analyzed by 31P NMR. The results indicated that both B. cereus PI-PLC and the PI-PLC-beta 1 from bovine brain catalyze conversion of DPPI to IP with overall retention of configuration at phosphorus. These results suggest that both bacterial and mammalian PI-PLCs catalyze the formation of IcP and IP by a sequential mechanism. However, the conversion of IcP to IP was detectable by 31P NMR only for the bacterial enzyme. Thus an alternative mechanism in which IcP and IP are formed by totally independent pathways, with formation of IP involving a covalent enzyme-phosphoinositol intermediate, cannot be ruled out for the mammalian enzyme. It was also found that both PI-PLCs displayed lack of stereo-specifically toward the 1,2-diacylglycerol moiety, which suggests that the hydrophobic part of phosphatidylinositol is not recognized by PI-PLC.
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PMID:Phospholipids chiral at phosphorus. Stereochemical mechanism for the formation of inositol 1-phosphate catalyzed by phosphatidylinositol-specific phospholipase C. 131 46

Phosphatidylcholine isolated from samples of bile, liver and plasma was converted into 1,2-diradylglycerobenzoate molecular species by hydrolysis with phospholipase C and reaction with benzoic anhydride. Up to seventeen molecular species were separated and determined by reversed-phase high-performance liquid chromatography with detection at 230 nm. The major improvement introduced here was the use of distearoylphosphatidylcholine as the internal standard, which corrected the results for incomplete hydrolysis and benzoylation. Other improvements concerned the clean-up of benzoyl derivatives and the chromatographic separation. The analytical results obtained were validated by comparison with the results of either lipid phosphorus or gas chromatographic determinations.
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PMID:Improved determination of individual molecular species of phosphatidylcholine in biological samples by high-performance liquid chromatography with internal standards. 163 97

Proton magnetic resonance imaging (MRI) and 31P magnetic resonance spectroscopy (MRS) have been used to study the response of the rat liver in situ to bromobenzene, a classic hepatotoxicant. A localized region of high proton signal intensity was seen in the perihilar region of the liver 24 hr after injection of a sublethal dose of bromobenzene. The signal intensity of the entire liver was increased at 48 hr with a gradual return approaching control values by 120 hr. These results are consistent with acute hepatic edema followed by repair of the damaged tissue. In vivo 31P MRS studies of the same rat livers were performed under conditions whereby localized, quantitative spectra could be obtained without surgical intervention. Initial concentrations of the major endogenous phosphorus-containing metabolites within the livers of control rats were 2.97 +/- 0.43 mM for the phosphomonoesters (PME), 2.92 +/- 0.56 mM for inorganic phosphate, 11.3 +/- 1.0 mM for phosphodiesters (PDE), 4.09 +/- 0.54 mM for ATP, and 0.56 +/- 0.50 mM for ADP and the intracellular pH was 7.39 +/- 0.14 (mean +/- SD, n = 10). Bromobenzene was found to cause statistically significant (p less than 0.05) changes in several of these metabolites: a decrease in hepatic ATP levels (20% at 24 hr; 27% at 48 hr), a decrease in PDE levels (15% at 24 hr; 18% at 48 hr), and an increase in the PME (63% at 24 hr; 84% at 48 hr). Both the proton MRI and the 31P MRS changes have an onset of 15-20 hr and maximum effect at 25-60 hr, but the MRS changes returned to normal well before the MRI changes. The decreased ATP levels indicate deleterious effects of bromobenzene on the bioenergetic status of the liver in situ, while the increase in PME, due to a selective increase in phosphocholine, suggests the activation of a phosphatidylcholine-specific phospholipase C in response to tissue damage. Trolox C, a potent inhibitor of lipid peroxidation, prevented the bromobenzene-induced hepatic edema (i.e., the increase in proton MRI signal intensity) and the bioenergetic deterioration (i.e., the decrease in ATP levels). However, the bromobenzene-induced increase in PME levels was not prevented by Trolox C. These results indicate that the process of lipid peroxidation plays a significant role in the hepatotoxicity of bromobenzene within the intact animal.
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PMID:The response of the rat liver in situ to bromobenzene--in vivo proton magnetic resonance imaging and 31P magnetic resonance spectroscopy studies. 194 10

(Rp)- and (Sp)-1,2-dipalmitoyl-sn-glycero-3-thiophosphoinositol (DPPsI) were synthesized as a mixture and their configurations assigned on the basis of the stereospecific hydrolysis catalyzed by phospholipase A2 (PLA2) from bee venom. PLA2 is known to be stereospecific to the Rp isomer of 1,2-dipalmitoyl-sn-glycero-3-thiophosphocholine (DPPsC) and 1,2-dipalmitoyl-sn-glycero-3-thiophosphoethanolamine (DPPsE). Since the configurations of (Rp)- and (Sp)-DPPsI correspond to those of (Sp)- and (Rp)-DPPsC, respectively, due to a change in priority, the isomer specifically hydrolyzed by PLA2 was assigned to (Sp)-DPPsI. The DPPsI analogues were then used to probe the mechanism and to elucidate the steric course of the reaction catalyzed by phosphatidylinositide-specific phospholipase C (PI-PLC) from Bacillus cereus and for both isozyme I and isozyme II of PI-PLC from guinea pig uterus. It was found that the Rp isomer of DPPsI is the preferred substrate for all three PI-PLCs. Thus PI-PLC shows the same stereospecificity as phosphatidylcholine-specific PLC (PC-PLC), which prefers the Sp isomer of DPPsC. The ratio of the two products inositol 1,2-cyclic phosphorothioate (cIPs) and inositol phosphorothioate (IPs) was not significantly perturbed by the use of phosphorothioate analogue for all three PI-PLCs, which implies that IPs is not produced by enzyme-mediated ring opening of cIPs and supports a parallel pathway for the formation of both products. In order to elucidate the steric course of the cyclization reaction, exo and endo isomers of cIPs were synthesized and their absolute configurations at phosphorus were determined by nuclear magnetic resonance and other techniques. It was found that exo-cIPs is the product produced by all three PI-PLCs. Thus the steric course of the conversion DPPsI to cIPs catalyzed by all three PI-PLCs was inversion of configuration at phosphorus. These results taken together suggest that the reaction catalyzed by PI-PLC most likely proceeds via direct attack by the 2-OH group to generate the cyclic product, and parallelly by water to generate the noncyclic inositol phosphates, without involving a covalent enzyme-phosphoinositol intermediate.
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PMID:Phospholipids chiral at phosphorus. Stereochemical mechanism of reactions catalyzed by phosphatidylinositide-specific phospholipase C from Bacillus cereus and guinea pig uterus. 216 Dec 55

In spontaneously hypertensive rats (SHR), enhanced responsiveness of phospholipase C has been reported in various cells and tissues. In SHR and in some patients with essential hypertension particularly, the increased phospholipase C responsiveness of platelets has been described as involved in the hyperreactivity to thrombin. To determine the relation between such an enzymic abnormality and hypertension, the platelet phospholipase C activity was investigated in various models of experimental hypertension (i.e., in the Dahl salt-resistant and salt-sensitive strains inbred by John Rapp at Toledo, Ohio, SR/Jr and SS/Jr, respectively) fed either on a low or a high NaCl-containing diet, and in deoxycorticosterone acetate (DOCA)-salt hypertensive rats. In phosphorus-32-prelabeled platelets, phospholipase C was determined by measurement of the thrombin-induced [32P]phosphatidic acid formation; the labeling of the P47 protein with 32P was also measured. In parallel experiments, the platelet reactivity was assessed by measurement of the thrombin-induced serotonin release. Under thrombin (0.05-0.5 units/ml) stimulation, phospholipase C activity, [32P]P47 labeling, and serotonin release were significantly increased in SS/Jr rats fed a high NaCl diet compared with SS/Jr rats fed a low NaCl diet. NaCl-rich diet did not modify phospholipase C in SR/Jr rats. Platelet reactivity and phospholipase C responsiveness were also normal in DOCA-salt hypertensive rats compared with controls.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Platelet phospholipase C activity in salt-dependent hypertension. 231 20

The susceptibility of partially peroxidized liposomes of 2-[1-14C] linoleoylphosphatidylethanolamine ([14C]PE) to hydrolysis by cellular phospholipases was examined. [14C]PE was peroxidized by exposure to air at 37 degrees C, resulting in the formation of more polar derivatives, as determined by thin-layer chromatographic analysis. Hydrolysis of these partially peroxidized liposomes by lysosomal phospholipase C associated with cardiac sarcoplasmic reticulum, and by rat liver lysosomal phospholipase C, was greater than hydrolysis of non-peroxidized liposomes. By contrast, hydrolysis of liposomes by purified human synovial fluid phospholipase A2 or bacterial phospholipase C was almost completely inhibited by partial peroxidation of PE. Lysosomal phospholipase C preferentially hydrolyzed the peroxidized component of the lipid substrate which had accumulated during autoxidation. The major product recovered under these conditions was 2-monoacylglycerol, indicating sequential degradation by phospholipase C and diacylglycerol lipase. Liposomes peroxidized at pH 7.0 were more susceptible to hydrolysis by lysosomal phospholipases C than were liposomes peroxidized at pH 5.0, in spite of greater production of polar lipid after peroxidation at pH 5.0. Sodium bisulfite, an antioxidant and an inhibitor of lysosomal phospholipases, prevented: (1) lipid autoxidation, (2) hydrolysis of both non-peroxidized and peroxidized liposomes by sarcoplasmic reticulum and (3) loss of lipid phosphorus from endogenous lipids when sarcoplasmic reticulum was incubated at pH 5.0. These studies show that lipid peroxidation may modulate the susceptibility of phospholipid to attack by specific phospholipases, and may therefore be an important determinant in membrane dysfunction during injury. Preservation of membrane structural and functional integrity by antioxidants may result from inhibition of lipid peroxidation, which in turn may modulate cellular phospholipase activity.
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PMID:Preferential hydrolysis of peroxidized phospholipid by lysosomal phospholipase C. 333 60


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