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

---

Query: EC:3.1.4.1 (phosphodiesterase)
18,767 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

1. The effects of secretin and pancreozymin-C-octapeptide and phosphodiesterase inhibitors on the concentration of adenosine 3',5'-cyclic monophosphate (cyclic AMP) and on the release of enzymes from rat pancreas have been studied. 2. In determininging cyclic AMP by means of the saturation assay of Brown et al. ((1971) Biochem. J. 121, 561-563) it is found essential to purify the pancreatic tissue extract by ion-exchange chromatography prior to the assay. 3. Injection of synthetic secretin or pancreozymin-C-octapeptide in anaesthetized rats in a secretory active dose (0.1 nmol) has no effect on the pancreatic cyclic AMP level. 4. Incubation for up to 10 min of pancreatic slices in Krebs-Ringer bicarbonate glucose medium containing 10(-2) M theophylline as phosphodiesterase inhibitor does not result in an increase of the cyclic AMP level. With 10(-2) M 1-methyl-3-isobutylxanthine as phosphodiesterase inhibitor the level is more than doubled after the first min of incubation and remains constant thereafter. 5. Addition of 3-10(-7) M secretin to slices incubated in the presence of 10(-2) M theophylline causes 84% increase of the cyclic AMP level above control, whereas the addition of 3-10(-7) M pancreozymin-C-octapeptide has no significant effect. In the presence of 10(-2) M 1-methyl-3-isobutylxanthine the latter hormone causes significant increases of up to 34% above control during 10 min of incubation. Secretin in this condition augments the cyclic AMP level by up to 296% above control during a 10 min incubation period. Addition of secretin and pancreozymin-C-octapeptide together has no greater effect than of secretin alone. 6. A broken cell fraction of rat pancreas contains adenylate cyclase activity which can be stimulated to 457 and 600% above the basal activity by 3-10(-7) M pancreozymin-C-octapeptide and secretin, respectively. Incubation of pancreatic slices with either hormone has no effect on the cyclic AMP phosphodiesterase activity in the homogenate of these slices. 7. Pancreozymin-C-octapeptide, dibutyryl cyclic AMP, 1-methyl-3-isobutylxanthine and carbamylcholine cause an elevated release of chymotrypsin from pancreatic slices incubated for 2 h in Krebs-Ringer bicarbonate medium, containing 10 mM glucose, while secretin, cyclic AMP and butyric acid have no significant effect. The release of the cytoplasmic enzyme lactate dehydrogenase is also elevated by dibutyryl cyclic AMP, 1-methyl-3-isobutylxanthine and carbamylcholine, but not significantly by pancreozymin-C-octapeptide. 8. The results support the role of cyclic AMP in the action of secretin, and do not exclude a mediating function of this nucleotide in the actions of pancreozymin in rat pancreas.
...
PMID:Rat pancreatic adenylate cyclase. IV. Effect of hormones and other agents on cyclic AMP level and enzyme release. 18 33

The CD (circular dichroism) and CPL (circular polarization of luminescence) spectra of NADPH in aqueous solution were studied and found to be markedly different. The spectra were not affected by cleavage of the coenzyme molecule with phosphodiesterase. The differences are thus not due to the existence of extended and folded conformations of NADPH and it is concluded that they originate in excited state conformational changes of the nicotinamide--ribose fragment. Opposite signs of both the CD and CPL spectra were observed for NADH bound to horse liver alcohol dehydrogenase and to beef heart lactate dehydrogenase indicating structural differences between the nicotinamide binding sites. The binding of substrate analogues to enzyme--coenzyme complexes did not affect the CD spectra and hence no significant conformational changes are induced upon formation of the ternary complexes. No changes in the CPL spectrum of NADH bound to lactate dehydrogenase were observed upon adding oxalate to form the ternary complex. Marked differences were found between the CPL spectra of binary and ternary complexes with liver alcohol dehydrogenase, while the CD spectra of these complexes were identical. It is concluded that a conformational change of the excited NADH molecule occurs in the binary but not in the ternary complex involving LADH, thus indicating an increased rigidity of the latter complex.
...
PMID:Circular dichroism and circular polarization of luminescence of reduced nicotinamide adenine dinucleotide in solution and bound to dehydrogenases. 20 11

1. Reactive Blue 2 (Cibacron Blue 3G-A) is a competitive inhibitor of bovine heart cyclic nucleotide phosphodiesterase (K(i) 0.3mum). The K(i) increases with increasing temperature, suggesting that hydrophobic interactions are not largely responsible for the binding of the dye. Another 25 sulphonated aromatic dyes are also competitive inhibitors of the cyclic nucleotide phosphodiesterase (K(i) values in the range of 0.06-13.6mum). 2. These dyes (covalently linked to Dextran 40) inhibit bovine heart cyclic nucleotide phosphodiesterase. Reactive Blue 2 (covalently linked to Dextran 40) is a competitive inhibitor of the phosphodiesterase (K(i) 0.4mum). 3. Bovine heart cyclic nucleotide phosphodiesterase is retained on a column of Reactive Blue 2-Sephacryl S-200 and can be eluted from the column by 3':5'-cyclic AMP. 4. A variety of the dyes (either free or covalently linked to Dextran 40) are competitive inhibitors of rabbit muscle lactate dehydrogenase. 5. The effectiveness of a wide range of structurally dissimilar dyes as competitive inhibitors of lactate dehydrogenase and cyclic nucleotide phosphodiesterase compromises proposals for the use of Reactive Blue 2 as a specific probe for the dinucleotide-binding structural domain present in many dehydrogenases and kinases. Detailed information of the various dyes used has been deposited as Supplementary Publication SUP 50089 (7 pages) at the British Library Lending Division, Boston Spa, Wetherby, West Yorkshire LS23 7BQ, U.K., from whom copies can be obtained on the terms indicated in Biochem. J. (1978) 169, 5.
...
PMID:The specific interaction of cibacron and related dyes with cyclic nucleotide phosphodiesterase and lactate dehydrogenase. 21 44

1. A mixed membrane fraction prepared from pig platelets was subfractionated, using the "B 14" zonal rotor, into two distinct subpopulations of membrane vesicles, each associated with a different phosphodiesterase activity. 2. The lighter subfraction (MI) was enriched 7-8 fold with bis-(p-nitrophenyl) phosphate phosphodiesterase activity and the denser subfraction (MII) showed a similar degree of enrichment of 5'dTMP-p-nitrophenyl ester phosphodiesterase activity. 3. Assays for other enzyme activities revealed slight enrichement (approx. 2 fold) of acid phosphatase, 3'-dTMP-p-nitrophenyl ester phosphodiesterase and beta-glucuronidase activities in MI, and beta-galactosidase in MII. Cyclic AMP phosphodiesterase, lactate dehydrogenase and N-acetyl-beta-glucosaminidase showed negligible activity in both MI and MII, and succinate dehydrogenase activity could not be detected in either subfraction. 4. Chemical analyses of the membrane subfractions demonstrated that MI contained approx. twice as much cholesterol, phospholipid, sialic acid and hexosamine per unit weight of protein than MII. These results are consistent with our previously reported observations from surface-labelling experiments, which indicated that MI was derived principally from the platelet surface-exposed membranes and that MII was probably intracellular in origin. 5. Analysis of the membrane polypeptides by sodium dodecyl sulphate-polyacrylamide gel electrophoresis revealed the presence of 12-15 components, in each subfraction, in the mol. wt. range 12000-200000, including a prominent band of approx. mol. wt. 46000, which has beeen identified to be actin. Qualitative as well as possible quantitative differences were apparent in that MII contained three components in addition to those present in MI. 6. Analysis of the periodate-Schiff staining components by sodium dodecyl sulphate-polyacrylamide gel electrophoresis demonstrated the presence of 4 major glycoproteins in both subfractions with apparent mol. wt. ranging from approx. 95000 to 150000; in addition two minor components were also present. Further, a very fast-migrating band, which did not stain with Coomassie blue, was observed in both MI and MII and probably represents lipid material.
...
PMID:Enzymatic and chemical analyses of pig platelet membrane subfractions isolated by zonal centrifugation. 127 16

To clarify a possible involvement of the vasoconstrictive peptide endothelin in the regulation of endothelial cell-mediated fibrinolytic system, confluent cultures of vascular endothelial cells from human umbilical vein were incubated in serum-free medium in the presence of endothelin-1 at 100 nM and below, and tissue plasminogen activator antigen (t-PA:Ag) in the medium was determined by enzyme immunoassay. Endothelin-1 at 1 nM and above significantly decreased the release of t-PA:Ag from the endothelial cells after a 24 h incubation. The t-PA:Ag release was also decreased by either endothelin-2 or endothelin-3 at 10 nM. The activity of lactate dehydrogenase in the medium was not changed by endothelin-1 at 100 nM and below, suggesting that the peptide did not cause nonspecific cell damage. The decrease in the t-PA:Ag release induced by endothelin-1 occurred in the presence or absence of 8-bromo cyclic AMP, which is an active congener of cyclic AMP; 3-isobutyl-1-methylxanthine, which is an inhibitor of phosphodiesterase; and forskolin, which is a stimulator of adenylate cyclase. These results strongly indicated that cyclic AMP which is known to down-regulate t-PA:Ag release was not involved in the endothelin-1 effect. However, endothelin-1 failed to decrease the t-PA:Ag release in the presence of either calcium ionophore A23187 or EGTA; the ionophore itself markedly decreased the release. The cytosolic calcium accumulation was significantly increased by endothelin-1. These results suggest that endothelin-1 decreases the release of t-PA:Ag from human endothelial cells through an excess accumulation of intracellular, especially cytosolic which would be mediated by an extracellular, calcium-dependent mechanism.
...
PMID:Endothelin modulation of tissue plasminogen activator release from human vascular endothelial cells in culture. 137 54

Normal human umbilical vein endothelial cells cultured on gelatin-coated plastic dishes were found to produce a protein in their media which had calmodulin-like immunoreactivity and biological activity. Further identification of the protein was achieved by examining the incorporation of 14C leucine into protein found in the conditioned medium. Cells produced 14C labelled protein in their medium which specifically bound to an affinity column for calmodulin. This latter material stimulated calmodulin dependent phosphodiesterase activity in vitro and this stimulation was inhibited by the addition of the calmodulin antagonist W7. The presence of calmodulin-like activity and immunoreactivity in the media varied as the cells grew from low to high density, a peak of extracellular calmodulin-like activity preceding an increase in cell number. Extracellular calmodulin-like activity did not correlate with the presence of lactate dehydrogenase in the medium. The addition of pure pig brain calmodulin affected the rate of cell proliferation; significant proliferation to pure calmodulin was only seen in cells at low density, at higher density calmodulin either had no effect or inhibited proliferation. Inhibition of extracellular calmodulin activity by a calmodulin antagonist immobilized on agarose beads, or by an antibody to calmodulin significantly decreased proliferation in all dividing cultures. Taken together this data suggests that, in vitro, calmodulin, or a very closely related protein, influences endothelial cell proliferation through an autocrine mechanism.
...
PMID:Mitogenic role for extracellular calmodulin-like activity in normal human umbilical vein endothelial cells. 141 89

Ouabain increases the enzyme secretion from the isolated rabbit pancreas and pancreatic fragments, but not from isolated pancreatic acini. The increase occurs after a delay of 45-60 min and is not accompanied by an increase in lactate dehydrogenase release. The stimulatory effect of ouabain (10(-5) M) is dependent on the presence of extracellular calcium, and is not antagonized by 10(-4) M atropin, 10(-4) M propranolol, 10(-5) M phentolamine, 10(-3) M dibutyryl-cyclic GMP, 10(-6) M tetrodotoxin, 10(-4) M verapamil or 10(-4) M D-600. Elevation of the extracellular potassium concentration to 120 mM in the presence of 10(-4) M atropin also increases the enzyme secretion from rabbit pancreatic fragments. The increase is again dependent on the presence of extracellular calcium and is resistant to adrenergic blockade and to tetrodotoxin, verapamil or D-600. Forskolin also stimulates a Ca2+-dependent release of amylase from pancreatic fragments but not from pancreatic acini. In the presence of the phosphodiesterase inhibitor 3-isobutyl-1-methylxanthine (IMX), ouabain (10(-5) M) and K+ (120 mM) cause an immediate increase in the cyclic AMP content of pancreatic fragments which does not occur in the absence of extracellular calcium. In pancreatic acini, the cAMP production is only slightly increased by ouabain. In the absence of IMX, the cAMP levels in fragments or acini are not detectably altered by ouabain or K+. The results suggest that the stimulation of enzyme secretion by ouabain and high K+ is an indirect effect, mediated by the release of an endogenous transmitter from non-cholinergic, non-adrenergic nerves in the intact preparations. The release and/or the effect of the transmitter appears to be mediated primarily by Ca2+ and secondarily by cyclic AMP.
...
PMID:Ouabain- and potassium-induced stimulation of amylase release in fragments and acini of rabbit pancreas. 240 77

The effect of prostaglandin E2 (PGE2) on the kinetic of bone resorption in vitro was assessed by following the release of minerals and degradation of matrix in cultured mouse calvarial bones. PGE2 (1 and 3 mumol/liter) caused an initial inhibition of the release of 45Ca, stable calcium, and inorganic phosphate from unstimulated calvarial bones. The effect was transient and after 24 and 48 hours the release of 45Ca, stable calcium, and inorganic phosphate from PGE2-treated bones was enhanced. 0.3 mumol/liter of PGE2 stimulated the release of 45Ca after 24 hours, but at this concentration no initial inhibition was observed. The initial inhibitory effect of PGE2 (1 mumol/liter) could be further increased by three structurally different inhibitors of cyclic AMP breakdown. PGE2 (1 mumol/liter) caused not only an initial inhibition of mineral release but also an initial inhibition of matrix degradation, as assessed by the release of 3H from [3H]-proline labeled bones. In addition, PGE2 (3 mumol/liter), in the presence of the phosphodiesterase inhibitor isobutylmethylxanthine, caused a rapid (6 hours) inhibition of the release of the lysosomal enzymes beta-glucuronidase and beta-N-acetyl-glucosaminidase, without affecting the release of the cytosolic enzyme lactate dehydrogenase. Similar specific initial inhibition of lysosomal enzyme release was also seen in the presence of calcitonin and dibutyryl cyclic AMP, but not in the presence of parathyroid hormone (PTH). Neither PGE2 nor the phosphodiesterase inhibitors rolipram and Ro 20.1724, could inhibit the initial stages of PTH-induced 45Ca release. Nor did PGE2 inhibit the stimulation of radioactive calcium mobilization induced by 1 alpha (OH)-vitamin D3.(ABSTRACT TRUNCATED AT 250 WORDS)
...
PMID:Prostaglandin E2 causes a transient inhibition of mineral mobilization, matrix degradation, and lysosomal enzyme release from mouse calvarial bones in vitro. 244 May 32

Exposure of cultured bovine pulmonary endothelial cells to endotoxin (lipopolysaccharide, LPS) causes cytotoxicity and increased prostacyclin production. Since cyclic nucleotides have been proposed as modulators of inflammation, we wondered whether they were involved in LPS-induced endothelial damage. Bovine pulmonary endothelial cells were exposed for 24 h to LPS and the effects of 1-methyl-3-isobutylxanthine (MIX), a phosphodiesterase inhibitor, dibutyryl cyclic AMP (db-cAMP), forskolin (an adenylate cyclase activator), and sodium nitroprusside (an agent known to stimulate intracellular cyclic GMP generation) on LPS-induced injury were determined. Injury was assessed by measurement of lactate dehydrogenase (LDH) (activity) and prostacyclin (6-keto-PGF1 alpha) in the bathing medium. Incubation with MIX attenuated LPS-induced endothelial cytotoxicity and prostacyclin production in a dose-dependent manner (ANOVA, p less than 0.001). Dibutyryl cyclic AMP also inhibited LPS-stimulated LDH release from the endothelial cells but did not suppress increased prostacyclin production. The combinations of MIX and dibutyryl cyclic AMP produced protection similar to that of MIX alone. Neither nitroprusside nor forskolin affected LPS-induced endothelial injury. Measurements of intracellular cyclic nucleotide concentrations showed that MIX caused marked increases in both cyclic AMP and cyclic GMP within 30 min of incubation, while forskolin and nitroprusside failed to cause such early elevations. Thus, phosphodiesterase inhibition protects endothelial cells from the effects of LPS. Increased intracellular concentrations of cyclic AMP also protect endothelial cells from LPS-induced cytotoxicity but do not alter the prostanoid response. We conclude that increased intracellular concentrations of cyclic AMP protect against LPS-induced endothelial cytotoxicity if present early in the exposure. We further conclude that LPS-mediated endothelial cytotoxicity can be separated from increased prostacyclin production.
...
PMID:Attenuation of endotoxin-induced cytotoxicity and prostacyclin production in cultured bovine pulmonary artery endothelial cells by phosphodiesterase inhibition. 246 43

Nucleoside diphosphokinase (NDK) of human platelets has been purified by chromatography on Blue Sepharose CL-6B gel (purification factor of 950) and shown to be free of adenylate kinase, ATPase and adenylate cyclase. The molecular weight was 70,000 with subunits of 17,000. The pH optimum was 8.0 Km values for ATP and dTDP were determined in two ways using the pyruvate kinase-lactate dehydrogenase coupled enzyme assay. Values of 0.38 and 0.20 mM were obtained for ATP and 0.29 and 0.21 mM for dTDP. Km values for ADP (0.024 mM) and GTP (0.12 mM) were determined with the hexokinase-glucose-6-phosphate dehydrogenase coupled enzyme assay. These values are in agreement with those reported for NDK from other sources. Theophylline, which inhibits the NDK activity of intact platelets and platelet membrane preparations and inhibits the ADP-induced shape change of platelets, was shown to be a competitive inhibitor of both the free and phosphorylated forms of NDK with competitive inhibition constants (Kic) of 9.3 and 9.6 mM respectively. Papaverine, another cAMP phosphodiesterase inhibitor, which also inhibits the ADP-induced shape change of platelets, had no inhibitory effect on platelet NDK. It was concluded that the inhibitory effect of theophylline on the activity of the purified enzyme was due to the structural similarity between the methylxanthine and the adenine moiety of ADP.
...
PMID:Isolation and kinetic studies of nucleoside diphosphokinase from human platelets and effects of cAMP phosphodiesterase inhibitors. 302 50


1 2 3 4 5 Next >>

---