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)

The role of the surrounding membrane structure on the binding characteristics of the insulin receptor was studied by using several digestive enzymes. The effects observed with particulate membrane preparations are compared with those from soluble receptor preparations. beta-Galactosidase and neuraminidase had no effect on insulin binding to either particulate or soluble receptors from human placentae. Exposure to 2 units of phospholipase C/ml increased insulin binding to particulate membranes, but was without effect on the soluble receptor preparation. The increase in binding to particulate membranes was shown to be due to an increase in apparent receptor number. After 5 min exposure to 500 microgram of trypsin/ml there was an increase in insulin binding to the particulate membrane fraction, owing to an increase in receptor affinity. After 15 min exposure to this amount of trypsin, binding decreased, owing to a progressive decrease in receptor availability. In contrast, this concentration of trypsin had no effect on the solubilized receptor preparation. Because of the differential effects of phospholipase C and trypsin on the particulate compared with the solubilized receptor preparations, it is concluded that the effects of these enzymes were due to an effect on the surrounding membrane structure. Changes in receptor configuration due to alterations within the adjoining membrane provide a potential mechanism for mediating short-term alterations in receptor function.
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PMID:The effects of digestive enzymes on characteristics of placental insulin receptor. Comparison of particulate and soluble receptor preparations. 10 Jan 6

1. The accessibility of phospholipids in the membrane of the adrenomedullary storage vesicles (chromaffin granules) has been studied. 2. The reaction of 2,4,6-trinitrobenzenesulphonic acid with both intact granules and their ghosts, results in the labelling of 70% of the phosphatidylethanolamine. 3. The action of phospholipase A2 (from bee venom), phospholipase C (from Bacillus cereus) and sphingomyelinase C (from Staphylococcus aureus) on granules and their ghosts was followed as a function of time. No significant difference was observed between the intact granules and their ghosts. 4. In the intact granules the various treatments led to varying amounts of lysis although again no evidence was obtained that such lysis in any way increased the amount of accessible phospholipid. 5. Highly purified granule preparations were also compared with the so-called "large granule" fraction and no significant differences were detected. 6. Approx. 67% of phosphatidylethanolamine + phosphatidic acid, 50% of phosphatidylserine + phosphatidylinositol, 65% of phosphatidylcholine and 20% of sphingomyelin is accessible to enzymatic degradation. In total, approx. 50% of all the phospholipids reacted. 7. It is also shown that, unlike in enzymatic treatment, all the phosphatidylcholine can be exchanged in the presence of a phospholipid exchange protein (prepared from beef liver). 8. It is concluded that transmembrane movement of phosphatidylcholine is slow in isolated membranes of chromaffin granules. The presence of the exchange protein, however, in conjunction with membrane proteins and specific phospholipid arrangements may catalyse this transmembrane movement.
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PMID:Accessibility of phospholipids in the chromaffin granule membrane. 10 48

The Rho(D) antigen of red cell membranes was solubilized using ethylene-diamine tetraacetic acid (EDTA) and 2-mercaptoethanol. The solubilized antigen was partially separated from other solubilized membrane components using molecular filtration. The antigen was treated with various enzymes to learn some of the chemical characteristics. It was found that the activity of the antigen, as measured by hemagglutination inhibition, was not affected by bee venom phospholipase A, Clostridium welchii phospholipase C, calf-intestinal alkaline phosphatase, Vibrio cholerae neuraminidase, pig kidney leucine aminopeptidase, bovine pancreatic carboxypeptidase A, and pig pancreatic carboxypeptidase B. However, the proteolytic enzymes, pronase, trypsin, chymotrypsin and papain, did destroy Rho(D) activity as measured by hemagglutination inhibition. These results indicate that protein is an important part of the active determinant of the Rho(D) antigen. The experiments by other investigators have shown that lipid is important to maintain the Rho(D) activity in the intact membrane; lipid probably helps to maintain the structural conformation of the Rho(D) molecule in its natural environment. The solubilized Rho(D) molecules are apparently not dependent on lipid for their Rho(D) activity.
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PMID:Studies on the characterization of the Rho(D) antigen. 10 79

1. The effect of lipolytic, glycolytic and proteolytic enzymes on the activities of plasma membrane enzyme activities in rat liver and kidney has been investigated by a pretreatment of tissue sections with the lytic enzymes. 2. The action of the proteolytic enzymes causes a very strong decrease of leucyl-beta-naphthylamidase activity, whereas the activities of ATP-ase, 5'-nucleotidase and alkaline phosphatase show a lesser decrease. This indicates a different membrane anchorage of leucyl-beta-naphthylamidase as compared to that of the phosphatases. 3. Treatment with glycolytic enzymes results in a decrease of 5'-nucleotidase and ATP-ase activity, whereas liver alkaline phosphatase and leucyl-beta-naphthylamidase show an increase in activity. 4. Treatment with phospholipase C gives about the same results. The very strong decrease of 5'-nucleotidase activity indicates a great dependence on phospholipids.
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PMID:A histochemical study about the influence of lytic enzymes on plasma membrane enzyme activities in rat liver and kidney. 10 67

1. When heated in 8 M-urea, phospholipase C(EC 3.1.4.3) from Bacillus cereus undergoes conformational transitions depending on the temperatures used. These transitions were studied by examining protein fluorescence, iodide quenching of protein fluorescence, u.v. difference spectroscopy, chemical availability of histidine residues in the enzyme, circular dichroism and catalytic activity. 2. Unless simultaneously exposed to elevated temperatures the enzyme appears to be unaffected by 8 M-urea. Removal of the two zinc atoms from the enzyme renders phospholipase C very sensitive to denaturation by 8 M-urea as indicated by fluorescence emission spectra and circular dichroism. 3. Both the native and the zinc-free enzymes are markedly more resistant to irreversible thermal inactivation in the presence of 8 M-urea than in its absence. 4. The response of the enzyme to 8 M-urea and the role of zinc in stabilizing the enzyme are discussed.
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PMID:Conformational studies on phospholipase C from Bacillus cereus. The effect of urea on the enzyme. 10 29

Phospholipase C (phosphatidylcholine choline-phosphohydrolase, EC 3.1.4.E) from Bacillus cereus (IAM-1208) was adsorbed to palmitoyl cellulose from a crude enzyme solution at pH 5--9. The adsorption was not influenced by ionic strength up to 2 M NaCl. The adsorbed enzyme was eluted almost completely by washing the cellulose with a suitable detergent, such as Triton X-100, Adekatol SO-120, Cation DT-205, or sodium deoxycholate. The enzyme was then purified by column chromatography on a palmitoylated textile (palmitoylated gauze) with an overall recovery of 91% and a 467-fold increase in specific activity over that of enzyme in the crude culture supernatant. Subsequent fractionation with acetone and chromatography on a Sephadex G-75 column separated two nearly homogeneous phospholipase C's. The enzyme adsorbed on palmitoyl cellulose was active, although its activity was about one-fourth that of free phospholipase C. Therefore, the enzyme appeared to be adsorbed to the cellulose through a hydrophobic site that was distinct from the catalytic site on the enzyme molecule.
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PMID:Purification of phospholipase C from Bacillus cereus by hydrophobic chromatography on palmitoyl cellulose. 11 Aug 96

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. Protein-fluorescence studies indicated that phospholipase C from Bacillus cereus is denatured in solutions of guanidinium chloride. The denaturation was not thermodynamically reversible and followed biphasic kinetics. 2. Guanidinium chloride solutions released the structural Zn2+ from the enzyme and rendered all histidine residues chemically reactive. In the presence of free Zn1+ the enzyme was much more resistant to denaturation. Also, the addition for free Zn2+ to the denatured enzyme induced refolding. 3. The Zn2+-free apoenzyme was much more sensitive to guanidinium chloride than was the native enzyme and the denaturation appeared to be thermodynamically reversible. 4. Guanidinium chloride denaturation was associated with a reversible inactivation of the enzyme. Heat-inactivated, coagulated enzyme was substantially re-activated on dissolution in guanidinium chloride solutions followed by dialysis against a Zn2+-containing buffer.
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PMID:Unfolding and refolding of phospholipase C from Bacillus cereus in solutions of guanidinium chloride. 11

Serum antibodies against human coronavirus OC43 in different age groups were measured by complement fixation (CF), haemagglutination inhibition (HI), radial diffusion haemolysis-in-gel (HIG), and solid-phase radioimmunoassay (RIA) methods. Antigen grown in suckling mouse brain was used in all tests. Results obtained by the CF and HIG tests, and the RIA, were in good agreement with regard to the presence or absence of antibodies. Similar results were also obtained with the HI test if nonspecific haemagglutination inhibitors were first removed by treatment with phospholipase C and only titers of 1:20 or greater were considered positive. Children 6--23 months of age (n = 45) were without measurable coronavirus antibodies in all four assays. A rapid increase in the prevalence of antibodies then occurred in subsequent age groups, and practically all persons 6 years of age or older were found to have OC43 antibodies as measured by the HIG test or the RIA. The mean antibody levels determined by these two methods continued to increase, however, up to the age group of 10--14 years. This increase in antibody levels after the initial antibody incidence plateau may be due to boosting effects caused by related coronavirus strains, since OC43 antigens are known to cross-react with antibodies induced by other human coronaviruses. Taken together, these data suggest that OC43 virus, or an antigenically related coronavirus strain, is very common in Finland.
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PMID:OC43 strain-related coronavirus antibodies in different age groups. 11 4

The conditions necessary for the secretion of phospholipase C (phosphatidylcholine cholinephosphohydrolase) by Pseudomonas aeruginosa were studied. Enzyme secretion by washed cell suspensions required a carbon source and ammonium, potassium, and calcium ions. The calcium requirement could be substituted by magnesium and strontium but not by copper, manganese, cobalt, or zinc. During growth in liquid medium, cells secreted phospholipase C during late logarithmic and early stationary phases. Secretion was repressed by the addition of inorganic phosphate but not by organic phosphates, glucose, or sodium succinate. Studies with tetracycline indicated that de novo protein synthesis was necessary for the secretion of phospholipase C and that the exoenzyme was not released from a preformed periplasmic pool. Similarly, extraction of actively secreting cells with 0.2 M MgCl2 at pH 8.4 solubilized large quantities of the periplasmic enzyme alkaline phosphatase but insignificant amounts of phospholipase C. Bacteria continued to secrete enzyme for nearly 45 min after the addition of inorganic phosphate or rifampin.
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PMID:Secretion of phospholipase C by Pseudomonas aeruginosa. 11 87


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