Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.1.4.1 (phosphodiesterase)
 18,767 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

A method for the isolation of plasma membrane fractions from Xenopus oocytes has been developed, and the membranes have been characterized biochemically and morphologically. Plasma membrane complexes prepared by this procedure consisted of large sheets of the membrane, with associated vitelline envelope (a nonmembranous meshwork of fibers) and cortical (secretory) granules still attached. The morphology of cell surface microvilli and coated pits was well preserved. Cortical granules were removed by gentle homogenization in a low ionic strength medium, and integral and peripheral membrane proteins were then separated from vitelline envelopes by detergent extraction and phase separation in Triton-X-114. Biochemical characterization of the plasma membrane fractions indicated substantial levels of 5'-nucleotidase and alkaline phosphodiesterase activity associated with the oocyte cell surface, with 44-66% recovery of these markers in the final membrane preparations. Lectin blotting and lectin affinity chromatography with Concanavalin A and wheat germ agglutinin were used to characterize the major glycoprotein species associated with the plasma membrane complexes. Plasma membrane fractions prepared by this procedure should be very useful in both biochemical and morphological studies of membrane protein sorting in the Xenopus oocyte system.
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PMID:Isolation of plasma membrane complexes from Xenopus oocytes. 271 44

Bungarus candidus venom exhibited high hyaluronidase, acetylcholinesterase and phospholipase A activities; low proteinase, 5'-nucleotidase, alkaline phosphomonoesterase and phosphodiesterase activities and moderately high L-amino acid oxidase activity. SP-Sephadex C-50 ion exchange chromatographic fractionation of the venom and Sephadex G-50 chromatography of the major lethal venom fractions indicate that the venom contains at least two highly lethal, basic phospholipases A with LD50 (i.v.) values of 0.02 micrograms/g (F6A) and 0.18 micrograms/g (F4A), respectively; as well as two polypeptide toxins with LD50 (i.v.) values of 0.17 micrograms/g and 0.83 micrograms/g, respectively. The major lethal toxin is the basic lethal phospholipase A, F6A, which accounts for approximately 13% of the venom protein and has a mol. wt of 21,000.
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PMID:The lethal and biochemical properties of Bungarus candidus (Malayan krait) venom and venom fractions. 279 37

A venom exonuclease 'phosphodiesterase' (E.C. 3.1.4.1) has been purified from Cerastes cerastes venom by a combination of gel filtration on Sephadex G-100 superfine and ion exchange chromatography on DEAE-Sepharose. The enzyme showed a single band on PAGE and SDS-PAGE and had a molecular weight of 110,000. The final preparation was purified 28 fold. It had no carbohydrate and it did not have protease or 5'-nucleotidase activities. Optimum temperature for enzyme activity was 56 degrees C. The enzyme was rapidly inactivated when pre-incubated above 40 degrees C. Energy of activation (Ea) was calculated to be 0.913. The optimum pH was 9.0. Cysteine, glutathione, dithiothreitol, 2-mercaptoethanol, ADP and AMP inhibited the enzyme. Cysteine caused a non-competitive inhibition, while ADP showed a competitive inhibition. EDTA at a concentration of 0.5 mM caused complete inhibition of the enzyme, which could be reversed by the addition of Ca2+ or Mn2+.
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PMID:Purification and characterization of phosphodiesterase (exonuclease) from Cerastes cerastes (Egyptian sand viper) venom. 282 90

The two clinically important classes of antimycotic drugs, the polyenes and azoles, act on the plasma membrane of the cell. The primary modes of action are believed to be through interaction with sterols (polyenes) and alteration in sterol composition of the membrane (azoles). In this report we show that, at growth inhibitory concentrations, the polyenes (nystatin and amphotericin) and azoles (miconazole and ketoconazole) also inhibit plasma membrane enzymes. There was extensive (greater than 75%) inhibition of the Candida albicans plasma membrane enzymes ATPase, glucan synthase, adenyl cyclase and 5'-nucleotidase, when assayed in situ. The antifungals papulacandin and echinocandin, which inhibit glucan synthesis, also inhibited plasma membrane enzymes in situ; glucan synthase (greater than 90%), 5'-nucleotidase (greater than 80%) and ATPase (70-80%). Purified plasma membrane was prepared from yeast cells of C. albicans by two different techniques: concanavalin A stabilization and coating of spheroplasts with silica microbeads. In the purified plasma membrane vesicles prepared from concanavalin A the adenyl cyclase and phosphodiesterase were extensively (greater than 90%) inhibited by the three different classes of antifungal drugs; variable inhibition was observed with ATPase (70-100%). The 3',5'-cyclic phosphodiesterase of the plasma membrane purified by the microbeads method was almost completely inhibited by all of the antifungals tested and there was partial inhibition of ATPase (20-85%) and adenyl cyclase (30-90%).
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PMID:The effects of azole and polyene antifungals on the plasma membrane enzymes of Candida albicans. 283 Mar 94

The distribution of [3H]leukotriene D4 [( 3H]LTD4) receptors in subcellular membrane fractions obtained from sheep tracheal smooth muscle was studied. Using differential centrifugation and discontinuous sucrose density gradient centrifugation, the subcellular membranes were separated into six fractions. The [3H]LTD4 receptor distribution profile in these fractions correlated with markers for the plasma membrane (5'-nucleotidase and alkaline phosphodiesterase) and did not correlate with markers for the mitochondria (cytochrome c oxidase and succinate-dependent cytochrome c reductase). The dissociation constant (Kd) and maximum number of binding sites (Bmax) for [3H]LTD4 binding to the receptors in the crude mixture of membranes (PII) were 0.38 +/- 0.2 nM and 77 +/- 14 fmol/mg of protein, respectively. The Kd and Bmax of [3H]LTD4 binding to the receptors in the plasma membrane-enriched fraction (FII) were 0.40 +/- 0.2 nM and 268 +/- 46 fmol/mg of protein, respectively. The specificity profile of the [3H]LTD4 receptors in the plasma membrane-enriched fraction was equivalent to that observed in the crude membrane and correlated with the agonist myotonic activities in the smooth muscle contraction assay system. Furthermore, the binding of [3H]LTD4 to the plasma membrane receptors was modulated by guanine nucleotides in a manner analogous to that observed in crude membranes, suggesting that agonist interaction with the receptors was regulated by guanine nucleotide binding protein. These results suggest that, in sheep tracheal smooth muscle, the plasma membrane is the primary location of specific LTD4 receptors.
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PMID:Subcellular localization of leukotriene D4 receptors in sheep tracheal smooth muscle. 284 53

Cyclic AMP has been implicated as a regulator of capacitation, but the control of its metabolism in sperm remains obscure. A recent study of mouse sperm has shown capacitation-related changes in the activities of both adenylate cyclase, which increased during incubation, and cyclic nucleotide phosphodiesterase, which decreased. The present study was conducted to extend these observations by measuring phosphodiesterase activity in sperm incubated in media with modified calcium and/or glucose content, conditions known to modulate fertilizing ability. Phosphodiesterase activity of sequential sperm samples, taken first when sperm are essentially uncapacitated and then when they are either partially or completely capacitated, decreased with time under all conditions, and in each case the greater fall in activity was seen in the medium that would support the greater change in fertilizing ability of the sperm population. Sperm washed by centrifugation to remove epididymal fluid also displayed a reduction in phosphodiesterase activity with time. The medium surrounding the sperm contained about half of the total phosphodiesterase activity, as well as 5'-nucleotidase and adenosine deaminase. The crude enzyme preparation showed complex kinetic behavior when assayed over a range of cAMP concentrations, but the reduction in activity with time was seen at all substrate levels. The observed changes in phosphodiesterase activity, together with the increased adenylate cyclase activity seen under these sperm incubation conditions, would increase cAMP availability with time, thus providing further evidence for a fundamental role for cAMP in controlling the events of capacitation.
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PMID:Phosphodiesterase activity of mouse sperm incubated under conditions that modulate fertilizing potential in vitro. 285 27

1. The L-amino acid oxidase, hyaluronidase, alkaline phosphomonoesterase, protease, phosphodiesterase, acetylcholinesterase, phospholipase A and 5'-nucleotidase activities of 47 samples of venoms from all the six species of cobra (Naja), including five subspecies of Naja naja, were examined. 2. The results demonstrated interspecific differences in the venom contents of phospholipase A, acetylcholinesterase, hyaluronidase and phosphodiesterase. These differences in venom enzyme contents can be used for the differentiation of species of the genus Naja. 3. Thus, our results revealed a correlation between the enzyme composition of venom and the taxonomic status of the snake at the species level for the genus Naja.
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PMID:A comparative study of cobra (Naja) venom enzymes. 285 66

The activity of calmodulin as an activator of cAMP phosphodiesterase was assayed. AMP was hydrolyzed by 5'-nucleotidase, and the adenosine formed was measured by both liquid scintillation counting and spectrophotometry at 265 nm. Calmodulin activities measured by the two methods were equivalent, indicating that spectrophotometric assay of calmodulin can be used in place of the isotopic method.
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PMID:A spectrophotometric method for calmodulin assay. 285 35

The complexity of rat liver endosome fractions containing internalized radioiodinated asialotransferrin, asialo-(alkaline phosphatase), insulin and prolactin was investigated by using free-flow electrophoresis and isopycnic centrifugation in Nycodenz gradients. Two subfractions were separated by free-flow electrophoresis. Both subfractions contained receptors for asialoglycoprotein and insulin. Glycosyltransferase activities were associated with the more electronegative vesicles, whereas 5'-nucleotidase and alkaline phosphodiesterase activities were associated with the less electronegative vesicles. Three subfractions were separated on Nycodenz gradients. Two subfractions, previously shown to become acidified in vitro, contained the ligands. At short intervals after uptake (1-2 min), ligands were mainly in subfraction DN-2 (density 1.115 g/cm3), but movement into subfraction DN-1 (density 1.090 g/cm3) had occurred 10-15 min after internalization. Low amounts of glycosyltransferase activities were associated with subfraction DN-2, and 5'-nucleotidase and alkaline phosphodiesterase activities were mainly located in subfraction DN-1. The binding sites for asialoglycoproteins and insulin were distributed towards the higher density range in the Nycodenz gradients, thus indicating a segregation of receptor-enriched vesicles and those vesicles containing the various ligands 10-15 min after internalization. Electron microscopy of the subfractions separated on Nycodenz gradients indicated that whereas the ligand-transporting fractions consisted mainly of empty vesicles (average diameter 100-150 nm), the receptor-enriched component was more granular and smaller (average diameter 70-95 nm). The properties of the endosome subfraction are used to assign their origin to the regions of the endocytic compartment where ligand-receptor dissociation and separation occur.
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PMID:Subfractionation of hepatic endosomes in Nycodenz gradients and by free-flow electrophoresis. Separation of ligand-transporting and receptor-enriched membranes. 286 60

We have characterized ATP-dependent Ca2+ transport into highly purified plasma membrane fraction isolated from guinea pig ileum smooth muscle. The membrane fraction contained inside-out sealed vesicles and was enriched 30-40-fold in 5'-nucleotidase and phosphodiesterase I activity as compared to post nuclear supernatant. Plasma membrane vesicles showed high rate (76 nmol/mg/min) and high capacity for ATP dependent Ca2+ transport which was inhibited by addition of Ca2+ ionophore A23187. The inhibitors of mitochondrial Ca2+ transport, i.e., sodium azide, oligomycin and ruthenium red did not inhibit ATP-dependent Ca2+ uptake into plasma membrane vesicles. The energy dependent Ca2+ uptake into plasma membranes showed very high specificity for ATP as energy source and other nucleotide triphosphates were ineffective in supporting Ca2+ transport. Phosphate was significantly better as Ca2+ trapping anion to potentiate ATP-dependent Ca2+ uptake into plasma membrane fraction as compared to oxalate. Orthovanadate, an inhibitor of cell membrane (Ca2+-Mg2+)-ATPase activity, completely inhibited ATP-dependent Ca2+ transport and the Ki was approximately 0.6 microM. ATP-dependent Ca2+ transport and formation of alkali labile phosphorylated intermediate of (Ca2+-Mg2+)-ATPase increased with increasing concentrations of free Ca2+ in the incubation mixture and the Km value for Ca2+ was approximately 0.6-0.7 microM for both the reactions.
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PMID:Characterization of Ca2+ uptake in plasma membrane vesicles isolated from guinea pig ileum smooth muscle. 295 Oct 13


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