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)

Apparent values of Km and Vmax have been measured for catalysis of hydrolysis of unsonicated egg lecithin liposomes, activated through addition of 0.4 M n-hexanol, by phospholipases A2 from bee and snake venoms and by phospholipase C from Clostridium welchii as a function of the concentration of three surfactants: hexadecylamine, hexadecyltrimethylammonium bromide, and dihexadecyl phosphate. For all three enzymes, values of Km and Vmax show little or no dependence on the concentration of these ionic surfactants, demonstrating that the liposomal surface charge is not a crucial factor in determining susceptibility to phospholipase-catalyzed hydrolysis.
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PMID:Phospholipases. III. Effects of ionic surfactants on the phospholipase-catalyzed hydrolysis of unsonicated egg lecithin liposomes. 0 May 6

Phospholipase activity of 10 strains of Bacillus cereus was studied. The most active strain of Bac. cereus--phospholipase producer was selected. A cultivation mixture of Bac. cereus optimal for the phospholipase synthesis was found to include peptone, yeast extract, glucose, NaCl and Na2HPO4. Proper conditions for the synthesis of phospholipase in flasks, 20 l and 250 l fermenters were tested. The maximum increase of the phospholipase activity occurred by the 5-9th hour of microbial growth at pH 6.0-8.0. Further cultivation, foaming, strong aeration, pH increase (over 8.0) reduced the accumulated activity. By fractionation with (NH4)2SO4, ethanol precipitation, protamine sulphate treatment with subsequent Sephadex G-100 gel filtration phospholipase (EC 3.1.4.3) was purified 300-fold from the culture liquid of Bac. cereus str. 504. The preparation was examined electrophoretically in 7% polyacrylamide gel at alkaline pH. The effect of metal salts and EDTA on phospholipase activity was studied. Thermostability, substrate specificity and pH optimum of purified phospholipase were investigated.
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PMID:[Phospholipase of Bacillus cereus]. 1 9

Purification of phospholipase C from Bac. cereus by chromatography on aminoalkylpolysaccharide adsorbents is described. The dependence of the degree of enzyme purification on the amount of ligant and effect of pH and buffer systems on the adsorption-desorption of phospholipase have been studied. At a pH below 9.0 phospholipase C is not retained by the adsorbents and is purified 4-5-fold and up to 23-fold, when aminoalkyl-Sepharose and hexamethylenediamine Sephadex are used respectively. With an increase in the pH value up to 10.0, the enzyme is bound by the adsorbent and is eluted with a 40-90% yield of activity and 7-10-fold purification. The resulting phospholipase C is highly purified and electrophoretically homogeneous. A mechanism of the enzyme-adsorbent interaction is discussed.
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PMID:[Purification of phospholipase C from Bacillus cereus by chromatography on aminoalkylpolysaccharide adsorbents]. 1

The role of phospholipids in the binding of [3H]tetrodotoxin to garfish olfactory nerve axon plasma membrane was studied by the use of purified phospholipases. Treatment of the membranes with low concentrations of either phospholipase A2 (Crotalus adamanteus and Naja naja) or phospholipase C (Bacillus cereus and Clostridium perfringens) resulted in a marked reduction in tetrodotoxin binding activity. A 90% reduction in the activity occurred with about 45% hydrolysis of membrane phospholipids by phospholipase A2, and with phospholipase C the lipid hydrolysis was about 60--70% for a 70--80% reduction in the binding activity. Phospholipase C from B. cereus and Cl. perfringens had similar inhibitory effects. Bovine serum albumin protected the tetrodotoxin binding activity of the membrane from the inhibitory effect of phospholipase A2 but not from that of phospholipase C. In the presence of albumin about 25% of the membrane phospholipids remained unhydrolyzed by phospholipase A2. It is suggested that these unhydrolyzed phospholipids are in a physical state different from the rest of the membrane phospholipids and that these include the phospholipids which are directly related to the tetrodotoxin binding component. It is concluded that phospholipids form an integral part of the tetrodotoxin binding component of the axon membrane and that the phospholipase-caused inhibition of the binding activity is due to effects resulting from alteration of the phospholipid components.
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PMID:Effect of purified phospholipases on the binding of tetrodotoxin to axon plasma membrane. 3 72

The lipid and protein fractions of the endobronchial lavage fluid from the normal rats which contained the lung surfactant were analysed. Lecithin, the main main component of the lung surfactant, was exclusively combined with a dextran precipitable protein. This protein then behaved as beta-globulin on cellulose acetate electrophoresis or low density lipoprotein on agarose gel filtration. After administration of phospholipase C (from Clostridium Welchii), the protein content of the lavage fluid increased markedly. The amount of dextran precipitable protein also increased markedly and its properties remained the same on gel filtration after treatment with phospholipase C. The phospholipids in the lavage fluid were not affected, although the total phospholipids in the lung tissue, especially lecithin, did decrease during the 10 days after treatment. Histopathologically, an eosinophilic dense exudative fluid appeared in both the interstitium and the broncho-alveolar spaces. A large number of the alveolar lining cells disappeared and a few of them were desquamated into the alveolar spaces. Thus, the immediate destruction of the alveolar lining cells after the administration of phospholipase C resulted in interstitial pneumonia in 10 days. The significance of phospholipase in pulmonary inflammation is discussed.
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PMID:Lung damage caused by phospholipase C and the changes in phospholipids in the rat lung. 6 May 1

In the examined strains the production of following toxins or enzymes was determined by bioassay or by semiquantitative and routine diagnostical tests: delta-endotoxin, alpha-exotoxin, beta-exotoxin hemolysin, phospholipase C, proteinase. The production of delta-endotoxin (= a parasporal crystal toxic for several insects) is the only character in that B. thuringiensis differs from B. cereus. Other biochemical features as production of so-called alpha-exotoxin (= soluble toxic protein), hemolysin, phospholipase or proteinase are common in both species. Strains of B. megaterium may produce proteinase, but no phospholipase, hemolysin or alpha-exotoxin. The identity of the alpha-exotoxin of the B. cereus-thuringiensis group with any of the exoenzymes studied here could not be confirmed. At present, this toxin is only demonstrable by bioassay. Formation of beta-exotoxin (= soluble toxic nucleotide) is restricted to special strains of the B. cereus-thuringiensis group. -- All strains of B. megaterium tested do not produce any of the toxins quoted; they have found to be apathogenic under the experimental conditions. As the so-called "egg yolk clearing factor" is produced by all strains of B. megaterium (in contrast to strains of the B. cereus-thuringiensis group) it does not represent a factor of pathogenicity and therefore the term "gamma-exotoxin" is unfounded. -- Not too much attention should be paid in connection with taxonomic studies to the ability or non-ability of strains of bacteria to produce a special toxin.
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PMID:[Toxins and enzymes of several species of Bacillus, especially of the B. cereus-thuringiensis group (author's transl)]. 11 4

1. Haemoglobin-free erythrocyte ghosts were prepared in 40 imosM bicarbonate buffer, pH 7.4, containing 1 mM EDTA (40 imosM/l mM EDTA). The ghost preparation was highly permeable on preparation but partially resealed on incubation in media containing Ca-2+. 2. A partially purified preparation of phospholipase C from Clostridum welchii caused an increase in observed Mg-2+-ATPase activity, reflecting a change in the permeability of the ghost to substrate. The phospholipase did not decrease Mg-2+-ATPase even at the highest levels tested. Mg-2+-ATPase activity could therefore be used as a permeability indicatior in these experiments. 3. Both (Ca-2+, Mg-2+)-ATPase activities of the ghosts were progressively lost as a result of the phospholipid hydrolysis induced by phospholipase C. 4. When a haemolysin in the commercial preparation was destroyed by heat-treatment, deactivation of the (Ca-2+, Mg-2+)-ATPase and (Na+, K+, Mg-2+)-ATPases were still observed but permeability changes were greatly reduced. 5. The products of phospholipase action were not inhibitory to the Ca-2+, Mg-2+)-ATPase. 6. Lysolecithin brought about a reactivation of the (Ca-2+, Mg-2+)-ATPase which was superimposed upon permeability changes in the preparation. 7. Reactivation of the (Ca-2+, Mg-2+)-ATPase was brought about by a nonlytic, mixed lipid preparation without significant effect upon permeability. 8. Human erythrocyte (Ca-2+, Mg-2+)-ATPase therefore appears to be an enzyme which responds to perturbation of the lipid environment in the membrane and is a "lipid-dependant" enzyme.
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PMID:Hydrolysis of erythrocyte membrane phospholipids by a preparation of phospholipase C from Clostridium Welchii. Deactivation of (Ca-2+, Mg-2+)-ATPase and its reactivation by added lipids. 12 73

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 ability of bovine corpus luteum plasma membranes to bind 125I-choriogonadotropin has been examined after prior treatment of the membranes with phospholipases A, C, and D. Treatment of the purified membranes with low concentrations of phospholipases A and C resulted in the inhibition of the binding of 125I-choriogonadotropin to its receptors, whereas phospholipase D had no effect. Receptor activity was decreased by low concentrations of phospholipase A from either bee venom, Vipera russelli or Crotalus terrificus terrificus. Similarly, low concentrations of phospholipase C from Clostridium perfringens and Clostridium welchii also inhibited the binding activity while comparatively higher concentrations of phospholipase C from Bacillus cereus were required to achieve comparable inhibition. The time required to produce 50% inhibition of in vitro binding by phospholipases A and C was found to be 6 and 23 min, respectively. Upon either removal or chelation of calcium ions by ethylene glycol bis(beta-aminoethyl ether)-N,N'-tetraacetic acid (EGTA) both enzymes were completely inhibited as evidenced by the complete retention of the membrane binding activity. The decrease in the specific binding of choriogonadotropin to membranes after phospholipase digestion resulted in a decrease in the number of binding sites and was not accompanied by a change in the affinity of the hormone-receptor complex. The rates of association and dissociation of the 125I-choriogonadotropin-receptor complex and the equilibrium dissociation constant (Kd) were nearly identical in untreated and phospholipase-treated membranes. Phospholipases did not have any effect on the preformed hormone-receptor complex or on solubilized receptor. Filtration through Sepharose 6B of solubilized 125I-choriogonadotropin-receptor complex from untreated membranes or membranes which had been pretreated with phospholipase C prior to carrying out hormone binding did not alter the profile (Kav 0.38). Gel filtration of membranes treated with phospholipase A showed two peaks of bound radioactivity with distribution coefficients (Kav) of 0.08 and 0.35, respectively.
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PMID:Gonadotropin receptors in plasma membranes of bovine corpus luteum. I. Effect of phospholipases on the binding of 125I-choriogonadotropin by membrane-associated and solubilized receptors. 18 85


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