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)

ATP-dependent cyclic GMP phosphodiesterase activity (EC 3.1.4.16) associated with bovine retinal outer-segment fragment preparations was stimulated an order of magnitude by light, confirming the results of Miki et al. (1973) Proc. Natl. Acad. Sci. U.S. 70, 3820-3824 at Yale for the frog system. In contrast to the results of the Yale group, however, light stimulation was not observed for cyclic AMP as substrate. A direct relationship of bovine rhodopsin bleaching to phosphodiesterase activation differs from a previous report by the Yale group that full activation of the frog enzyme was achieved by bleaching of a maximum of 2% rhodopsin. Phosphodiesterase activity could be qualitatively removed from the fresh outer-segment preparations with isotonic sucrose which apparently did not disrupt the plasmalemma or discs. Activity recovered from the washing was not light sensitive. Two Km values were determined for cyclic AMP, 5 and 0.05 mM; for cyclic GMP a Km of 0.22 mM was found. All Km values were determined in the presence of 1 mM ATP in the dark. Sonication of fresh outer segments or storing at -20 degrees C abolished the light response. However, storage at -76 degrees C fully preserved it.
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PMID:Cyclic nucleotide phosphodiesterases associated with bovine retinal outer-segment fragments. 17 Sep 72

Activities of cyclic nucleotide phosphodiesterase were studied in rat uterus as a function of age, DNA and protein content. Linear kinetics were observed for uterine homogenate cyclic GMP (cGMP) phosphodiesterase activity, but anomalous double-reciprocal plots, suggestive of multiple enzyme forms, were observed for cyclic AMP (cAMP) hydrolysis, cAMP phosphodiesterase was therefore measured at high and low substrate concentrations, 200 muM and 0.25 muM cAMP, respectively, to approximate multiple enzyme activities. Based upon total organ content, the total cAMP and cGMP phosphodiesterase activities increased throughout uterine development, from 5-50 days of age. On the same basis, the apparent low KM cAMP phosphodiesterase increased only between days 5 and 15 and showed no significant increase between days 15 and 50. On the other hand, specific activities of an apparent low KM cAMP phosphodiesterase, expressed per mg of protein or per mug of DNA, showed a marked reduction in activity between 30 and 50 days of age. Chronic administration of 17beta-estradiol to immature rats increased their uterine protein content and decreased the specific activity of the apparent low KM cAMP phosphodiesterase. In another estrogen target tissue, the anterior pituitary, protein and DNA content also increased during development but no changes in specific activities of cyclic nucleotide phosphodiesterase were noted. These results suggest the possible participation of cyclic nucleotide phosphodiesterases in the induction of uterine growth and development by ovarian hormones.
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PMID:Cyclic nucleotide phosphodiesterases in uterine development. 17 92

Cyclic nucleotide phosphodiesterase activities of baby hamster kidney cells (BHK) grown in surface cultures were altered by modifying growth conditions. The untransformed BHK cells grown in medium containing 10% fetal calf serum showed non-linear LineweaverBurk plots for cyclic AMP phosphodiesterase activity with apparent Michaelis constants for cyclic AMP of approximately 5 and 30 muM. When these cells were placed in medium containing 1% fetal calf serum, linear kinetic plots for cyclic AMP phosphodiesterase with an apparent Km for cyclic AMP of approximately 20 muM were obtained. Modification of the apparent Km of BHK cell phosphodiesterase was detectable within 20 minutes after dillution of cells grown in 10% serum into fresh medium containing 1% serum. With the BHK cell line transformed with Rous sarcoma virus, differences in enzyme kinetics were not seen when these cells were diluted in 1% or 10% serum. In addition to the serum induced differences in the apparent Km of cyclic AMP phosphodiesterases of BHK cells, total cyclic AMP and cyclic GMP phosphodiesterase activities were also modified by growth conditions. BHK cells grown to high cell densities had three to five-fold higher total cyclic AMP activity than did the cells in less dense cultures. When the dense cell cultures were diluted into fresh medium containing 10% serum, total enzyme activities fell to levels comparable to those found in the rapidly growing cells at low cell densities. The reduction in total enzyme activity after dilution of BHK cells occurred rapidly and was influenced by cell density. A similar reduction of total enzyme activity was also seen in diluted RSV cells; however, the time course of the response differed from that seen in the untransformed cells.
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PMID:Effects of growth conditions on cyclic nucleotide phosphodiesterases of cultured fibroblasts. 17 99

Cyclic AMP and cyclic GMP phosphodiesterase activities (3',5'-cyclic AMP 5'-nucleotidohydrolase, EC 3.1.4.17) were investigated in the human thyroid gland from patients with hyperthyroidism. Low substrate concentration (0.4 muM) was used. About 60% of the cyclic-AMP and 80% of the cyclic-GMP hydrolytic activities in the homogenate were obtained in the soluble fraction (105 000 X g supernatant). The thyroid gland contains two forms of cyclic-AMP phosphodiesterase, one with a Km of 1.3-10(-5) M and the second with a Km of 2-10(-6) M. Cyclic-AMP and cyclic-GMP phosphodiesterase were purified by gel filtration on a Sepharose-6B column. Cyclic-AMP phosphodiesterase activities were found in a broad area corresponding to molecular weights ranging from approx. 200 000 to 250 000 and cyclic-GMP phosphodiesterase activity was found in a single area corresponding to a molecular weight of 260 000. Cyclis-AMP phosphodiesterase activities were stimulated by the protein activator which was found in human thyroid and this stimulation was dependent on Ca2+. Stimulation of cyclic-AMP phosphodiesterase by the activator was not significant even in the presence of enough Ca2+. The effect of D,L-triiodothyronine, D,L-thyroxine, L-diiodotyrosine, L-monoiodotyrosine, L-thyronine, L-diiodothyronine, thyrotropin, hydrocortisone, adrenocorticotropin, cyclic-AMP and cyclic-GMP on the phosphodiesterase activities was studied. Cyclic-AMP, cyclic-GMP, D,L-triiosothyronine, D,L-thyroxine, adrenocorticotropin and hydrocortisone where found to inhibit the phophodiesterase. Triiodothyronine and thyroxine inhibited cyclic-AMP phosphodiesterase more effectively than cyclic-GMP phosphodiesterase. Thyroxine was a more potent inhibitor than triiodothyronine. The concentration of cyclic AMP producing a 50% inhibition of cyclic-GMP phosphodiesterase activity was 5-10(-5) M, while the concentration of cyclic GMP producing a 50% inhibition of cyclic-AMP phosphodiesterase was 3-10(-3) M. Both cyclic-AMP and cyclic-GMP phosphodiesterase activities in the homogenate of hyperthyroidism, thyroid carcinoma and adenoma were higher than in normal thyroid tissue, when assayed with a low concentration of the substrate (0.4 muM). When a higher concentration (1 mM) of cyclic nucleotides was used as the substrate, cyclic-AMP hydrolytic activity in adenoma tissue was similar to that of normal tissue, while the other activities were higher than normal.
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PMID:Human thyroid cyclic nucleotide phosphodiesterase. Its characterization and the effect of several hormones on the activity. 18 33

Bio-Gel A-5m chromatography has been used to separate apparent multiple forms of cyclic nucleotide phosphodiesterase from rat erythrocytes. Cyclic AMP phosphodiesterase was resolved by gel filtration into three peaks of activity with apparent molecular weights of about 300,000, 225,000 and 100,000, while cyclic GMP phosphodiesterase activity in gel column fractions was too low to permit meaningful estimates of its molecular weight. All three of the separated peaks of cyclic AMP phosphodiesterase activity displayed anomalous kinetic behaviour suggestive of negative cooperativity. The possibility that multiple phosphodiesterase activities could arise from in vitro alterations of a single enzyme was investigated. Similar changes in gel filtration profiles resulted when erythrocyte extracts were treated with trypsin or ammonium sulfate or were incubated at 37 degrees C. After these treatments, a large proportion of the enzyme activity occurred in low (ca. 100,000) molecular weight regions. The low molecular weight phosphodiesterase activities from untreated, incubated, and trypsin-treated extracts possessed similar properties. All were inhibited by methylxanthines, had pH optima of approximately 8.0, and similar kinetic properties and requirements for divalent cations. These observations raise the possibility that preparative procedures or limited proteolysis occurring during preparation and handling of extracts can contribute to the apparent multiplicity of enzyme forms seen after gel filtration of phosphodiesterase from rat erythrocytes and perhaps other cell types.
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PMID:Apparent multiple forms of cyclic AMP phosphodiesterase from rat erythrocytes. 18 74

The in vitro effects of insulin on different phosphodiesterase activities present in rat epididymal fat cells from normal and hypothyroid rats have been studied. Evidence is presented that insulin increases the maximum velocity of a particulate, low Km, cyclic adenosine-3', 5'-monophosphate (cyclic AMP) phosphodiesterase in both types of cells, this effect being more clearly evident with the fat cells from hypothyroid animals; combination of insulin and thyroidectomy resulted in a 400% stimulation with 10-10 - 10-9 M insulin. A clear and significant effect was apparent at 10-11 M insulin. However, the dose-response curve was biphasic, since stimulation by insulin was suppressed for doses of hormone higher 10-8 - 10-7 M. Moreover, insulin effects were very fast, since clear stimulation was observed after only 2 min of incubation; the maximal increase was obtained after 10 min. Insulin did not significantly affect the soluble cyclic AMP phosphodiesterase activity in normal cells, thus confirming results obtained by others. However, the soluble cyclic AMP phosphodiesterase activity was clearly stimulated by insulin when the fat cells were prepared from hypothyroid rats. Maximal stimulation was obtained with 10-9 M insulin; the response was again very fast. Soluble cyclic GMP phosphodiesterase activity was also increased additively by hypothyroidism and insulin, maximal stimulation being obtained with 10-9 M insulin. With this dose of insulin the additive effects of thyroidectomy and insulin produced a 5-fold stimulation. The effect of insulin on the soluble cyclic GMP phosphodiesterase was very fast (2-5 min). With both soluble cyclic nucleotide phosphodiesterase activities, insulin increased the maximal velocity but not apparent Km of the enzyme. Thus, hypothyroidism and insulin produced additive effects suggesting a different mechanism of action of these two hormonal situations on the degradation of the intracellular pools of cyclic AMP and cyclic GMP.
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PMID:Cyclic nucleotide phosphodiesterases, insulin and thyroid hormones. 18 75

An extract of rat liver or human platelet displayed three cyclic 3':5'-nucleotide phosphodiesterase activity peaks (I, II, and III) in a continuous sucrose density gradient when assayed with millimolar adenosine 3':5'-monophosphate (cAMP) or guanosine 3':5'-monophosphate (cGMP). The three fractions obtained from each nucleotide were not superimposable. The molecular weights corresponding to the three activity peaks of cAMP phosphodiesterase in rat liver were approximately: I, 22,000; II, 75,000; and III, 140,000. In both tissues, fraction I was barely detectable when assayed with micromolar concentrations of either nucleotide, presumably because fraction I has low affinity for cAMP and cGMP. Any one of the three forms upon recentrifugation on the gradient generated the others, indicating that they were interconvertible. The multiple forms appear to represent different aggregated states of the enzyme. The ratio of the three forms of cAMP phosphodiesterase in the platelet was shifted by dibutyryl cAMP (B2cAMP) and by the enzyme concentration. B2cAMP enhanced the formation of fraction I. Low enzyme concentration favored the equilibrium towards fraction I, while high enzyme concentration favored fraction III. When phosphodiesterase activities in the extract of rat liver, human platelets, or bovine brain were examined as a function of enzyme concentration, rectilinear rates were observed with micromolar, but not with millimolar cAMP or cGMP. The specific activity with millimolar cAMP was higher with low than with high protein concentrations, suggesting that the dissociated form catalyzed the hydrolysis of cAMP faster than that of the associated form. In contrast, the specific activity with millimolar cGMP was lower with low than with high protein concentrations. Supplementing the reaction mixture with bovine serum albumin to a final constant protein concentration did not affect the activity, suggesting that the concentration of the enzyme rather than that of extraneous proteins affected the enzyme activity. A change in enzyme concentration affected the kinetic properties of phosphodiesterase. A low enzyme concentration of cAMP phosphodiesterase yielded a linear Lineweaver-Burk plot, and a Km of 1.2 X 10(-4) M (bovine), 3 X 10(-5) M (platelet), or 5 X 10(-4) M (liver), while a high enzyme concentration yielded a nonlinear plot, and apparent Km values of 1.4 X 10(-4) M and 2 X 10(-5) M (brain), 4 X 10(-5) M and 3 X 10(-6) M (platelet), or 4 X 10(-5) M and 3 X 10(-6) (liver). Since a low enzyme concentration favored fraction I, the dissociated form, whereas a high enzyme concentration favored fraction III, the associated form, these kinetic constants suggest that the dissociated form exhibits a high Km and the associated form exhibits a low Km. In contrast, a high enzyme concentration gave a linear kinetic plot for cGMP phosphodiesterase, while a low enzyme concentration gave a nonlinear plot...
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PMID:Cyclid 3':5'-nucleotide phosphodiesterase. Interconvertible multiple forms and their effects on enzyme activity and kinetics. 18 86

Exceptionally high levels of guanosine 3'-5'-cyclic monophosphate (cyclic GMP) in the accessory reproductive gland of the male house cricket, Acheta domesticus, led to an investigation of cyclic nucleotide phosphodiesterase (EC 3.1.4.--) as a possible regulatory enzyme. Cricket cyclic nucleotide phosphodiesterase activity with cyclic GMP or cyclic AMP as substrate had a pH optimum around 9.0, required Mg2+ or Mn2+ for maximal activity, and was inhibited by EDTA and methylxanthines. Cyclic GMP phosphodiesterase occurred mainly in the soluble fraction of homogenates of accessory glands or whole crickets, but cyclic AMP phosphodiesterase in the accessory gland was primarily particulate. Kinetic analysis indicated three forms of cyclic GMP phosphodiesterase, with Km values at 2.9 muM, 71 muM and 1.5 mM. Chromatography of whole cricket or accessory gland extracts on DEAE cellulose gave an initial peak having comparable activity with either cyclic GMP or cyclic AMP, and a second peak specific for cyclic AMP. There were no appreciable changes in the specific activity or kinetic properties of accessory gland cyclic GMP phosphodiesterase during a developmental period over which cyclic GMP levels rise more than 500-fold. Thus, the accumulation of cyclic GMP in the accessory gland is probably not associated with concomitant developmental modulation of phosphodiesterase activity.
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PMID:Cyclic nucleotide phosphodiesterases in the cricket, Acheta domesticus. 18 17

The genome of Drosophila melanogaster has been surveyed for chromosomal regions which exert a dosage effect on the activities of cAMP phosphodiesterase or cGMP phosphodiesterase. Two regions increase cAMP phosphodiesterase activity when present as duplications. A region of the X chromosome increases cAMP phosphodiesterase activity when duplicated and decreases that activity when deficient. This region has been delimited to chromomeres 3D3 and 3D4, with 3D4 being the most probable locus, and may contain a structural gene for cAMP phosphodiesterase. A region on the third chromosome, 90E-91B, increases cAMP phosphodiesterase activity when duplicated but has no effect on the activity when deficient. Two regions increase cGMP phosphodiesterase activity when present as duplications. A region of the X chromosome, 5D-9C, increases cGMP phosphodiesterase activity when duplicated, but smaller duplications covering this region fail to show such an increase, indicating that a single locus is not responsible for the increase observed for the larger duplication. A region of the third chromosome, 88C-91B, also increases cGMP phosphodiesterase activity when duplicated. Smaller duplications covering this region show smaller increases than that observed for the larger duplication, suggesting that at least three loci between 88C and 91B contribute to the observed increase by that region. Deficiencies covering region 88C-91B do not affect cGMP phosphodiesterase activity. No locus for a presumptive structural gene for cGMP phosphodiesterase has been found. Limitations of the use of segmental aneuploidy in locating structural genes for enzymes are discussed.
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PMID:A cytogenetic analysis of cyclic nucleotide phosphodiesterase activities in Drosophila. 19 63

The inhibitor constants of several inhibitors for cyclic AMP- and cyclic GMP-phosphodiesterase from various organs are compared. The inhibitors were classical theophyline, papaverine, and some of newly developed inhibitors: an imidazolidinone compound, RO20-1724, and two phthalazinol compounds, EG 467 and EG 626. Among the inhibitors tested, papaverine and EG 626 were found to be the most potent. Both compounds were extremely inhibitory to platelet and arterial phosphodiesterases. EG 626 was much more inhibitory to cyclic AMP phosphodiesterase than to cyclic GMP phosphodiesterase in platelet- and brain-extract and RO20-1724 was inhibitory to cyclic AMP- but not cyclic GMP-phosphodiesterase in brain-extract. When the skin adenyl cyclase was activated by AMP, the addition of theophylline blocked this activation, but EG 626 or EG 467 further potentiated the activation. These in vitro studies may serve as basic screening tests for the effectiveness of the specific phosphodiesterase inhibitors.
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PMID:Phosphodiesterase inhibitors: their comparative effectiveness in vitro in various organs. 19 77


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