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

In the cells of the phototrophic bacteria Rhodospirillum rubrum and Rhodopseudomonas palustris the two enzymes of the cAMP system enzymes - adenylate cyclase and cAMP phosphodiesterase (PDE) exist in a soluble and membrane-bound forms. After mild disruption of the cells (sonication up to 3 min) the activity of both enzymes is found in the chromatophores. In the cells of the two types of bacteria grown under anaerobic conditions soluble adenylate cyclase is predominant. In the cells of R. rubrum the soluble form of PDE posesses higher activity, whereas in the cells of Rh. palustris a higher activity is observed in the membrane-bound form. In addition to their different localization in the cells, the PDE forms of Rh. rubrum differ in their ratios to the concentrations of hydrogen ions and bivalent metals; the latter difference, however, may be accounted for by the effect of a protein modulator of PDE. The pH optimum of membrane-bound PDE is 9.15. Soluble PDE has two activity maxima at pH 7.5 and 8.7. It is probable that similar to the animal tissue enzyme, PDE from Rh. rubrum exists in the soluble phase in at least tw forms. Close pH optima for soluble adenylate cyclase and for one of the soluble PDE forms (about 8.5) may indicate the unidirectional control of these enzymes by hydrogen ion concentration.
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PMID:[Subcellular distribution and several properties of the cAMP enzyme system of phototrophic bacteria]. 2 30

Carbenoxolone slightly but significantly decreased the release of FFA from rat epididymal fat pads. The antilipolytic action of carbenoxolone was not blocked by 10(-3)M 3-isobutyl-1-methylxanthine, a potent inhibitor of phosphodiesterase. The findings suggest that carbenoxolone exerts its antilipolytic activity by acting on adenylate cyclase, thereby decreasing cyclic AMP concentrations and the activity of the hormone-sensitive lipase in adipose tissue.
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PMID:Effect of carbenoxolone on lipolysis in rat adipose tissue. 2 44

Thermostable protein fraction from retina of rats with hereditary retinal dystrophy (Hunter and Campbell strains) did not inhibit cyclic nucleotide phosphodiesterase. At the same time an inhibitory component, found in retina of Wistar rat, rabbit, frog and lamprey, was similar to the component from bovine retina. Quantity of the inhibitory component in normal rat retina decreased considerably within postnatal period (12 days--3 months). Thermostable proteins, isolated from Campbell rat retina, differed from that of Hunters' one by electrophoretic properties while both preparations were dissimilar to the protein of normal rat. Protein bands, containing inhibitory component from dystrophic rat retina, appear to be less distinct as compared to those of normal rat. These proteins, eluated from the bands of Campbell rats, activated phosphodiesterase but the preparations from Hunter rats did not influence on it.
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PMID:[Protein inhibitor of cyclic nucleotide phosphodiesterase in the retina in hereditary degeneration]. 2 6

Phosphodiesterase activity is estimated in extracts and partially purified preparations from functionally different parts of bovine tongue. The enzyme activity varied from 4.0 to 10.4 nmole/mg of protein/min. Properties of phosphodiesterase from circumvallate papillae are studied, the pH optimum being 8.0--8.5, Km for cAMP--1.5.10(-4) M and for cGMP--6.5.10(-5) M. The enzyme activity did not change after the treatment with trypsin, protamine sulphate (0.01--1.0%), heparin (0.01--1.0) and taste agents: L-leucine (from 1.10(-2) M to 1.10(-5) M), quinine (from 4.10(-3) M to 4.10(-8) M) and D-glucose (from 1.10(-1) M to 1.10(-4) M). The protein inhibitor of the enzyme, isolated from retina external rod-cell segments considerably suppressed phosphodiesterase activity, and the protein activator from brain tissue stimulated it insignificantly. Thermostable protein modulators, which inhibit or activate (depending on experimental conditions) phosphodiesterase activity, are isolated from circumvallate papillae.
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PMID:[Properties of cyclic nucleotide phosphodiesterase from lingual taste papillae]. 2 46

Rabbit heart membranes possessing the adenylate cyclase activity were isolated and purified by extraction with high ionic strength solutions and centrifugation in the sucrose density gradient. It was shown that the membranes are characterized by a high percentage of cholesterol (molar ratio cholesterol/phospholipids is 0.24) and an increased activity of Na, K-ATPase, which suggests the localization of adenylate cyclase in the sarcolemma. During centrifugation in the sucrose density gradient the activities of andenylate cyclase and Na,K-ATPase are not separated. Treatment of heart sarcolemma with a 0.3% solution of lubrol WX results in 10--20% solubilization of adenylate cyclase. Purification of the enzyme in the membrane fraction is accompanied by a decrease in the activity of phosphodiesterase; however, about 2% of the heart diesterase total activity cannot be removed from the sarcolemma even after its treatment with 0.3% lubrol WX. Epinephrine and NaF activate adenylate cyclase without changing the pH dependence of the enzyme. The alpha-adrenergic antagonist phentolamine has no effect on the adenylate cyclase activation by catecholamines, glucagon and histamine; the beta-adrenergic antagonist alprenolol competitively inhibits the effects of isoproterenol, epinephrine and norepinephrine, having no effect on the enzyme activation by glucagon and histamine. There is no competition between epinephrine, glucagon and histamine for the binding site of the hormone; however, there may occur a competition between the hormone receptors for the binding to the enzyme. A combined action of several hormones on the membranes results in the averaging of their individual activating effects. When the hormones were added one after another, the extent of adenylate cyclase activation corresponded to that induced by the first hormone; the activation was insensitive to the effect of the second hormone added. It is assumed that the outer membrane of myocardium cells contains a adenylate cyclase and three types of receptors, each being capable to interact with the same form of enzyme. The activity of adenylate cyclase is determined by the type of the receptor, to which it is bound and by the amount of the enzyme-receptor complex.
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PMID:[Isolation, purification and characterization of regulatory properties of adenylate cyclase from rabbit heart]. 2 49

Various receptor-linked cyclic AMP systems were measured in rat neostriatum 2--14 days after selective destruction of neuronal cell bodies and dendrites by micro-injection of 3 microgram of kainic acid. Basal adenylate cyclase activity was reduced by up to 56% in the injected side and the sensitivity to dopamine was abolished. Up to 84% of cyclic nucleotide phosphodiesterase activity, hydrolyzing either cyclic AMP or cyclic GMP, was destroyed by kainic acid injection. Specific binding of [3H]etorphine and [3H]spiroperidol was reduced by up to 62% in the injected side, while non-specific binding was unchanged. All of these changes were time-dependent, and were greatest 7--14 days after kainic acid treatment. On the other hand, intrastriatal kainic acid injection caused no change in the steady-state concentration of cyclic AMP in striatal slices, or in the in vivo cyclic AMP content in the striatum of rats killed by microwave irradiation. Receptor-mediated increases in cyclic AMP accumulation in striatal slices were either unchanged or markedly potentiated by kainic acid treatment. The maximum response to adenosine was unchanged, while the response to isoprenaline was increased up to 3.7-fold, the response to dopamine increased up to 6.7-fold, and the response to PGE1 increased up to 30-fold. The effect of dopamine in kainic acid-treated striatal slices was no longer blocked by fluphenazine, but was blocked by propranolol, suggesting an interaction of dopamine with a beta-adrenoceptor in kainic acid-treated slices. The results suggest differential cellular localizations of the various receptor-linked cyclic AMP systems in rat neostriatum. Some dopamine and opiate receptors, as well as most of the phosphodiesterase activity, are associated with local neuronal elements, while beta-adrenoceptor, adenosine and PGE1 alterations in cyclic AMP are not. The potentiation of the beta-adrenoceptor and PGE1 responses suggests that they may occur in glial cells. In addition, the pool of adenylate cyclase destroyed by kainic acid appears to make little contribution to normal levels of cyclic AMP in the tissue.
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PMID:Receptor-linked cyclic AMP systems in rat neostriatum: differential localization revealed by kainic acid injection. 2 87

Isoproterenol (10(-5) and 10(-4)M) inhibited a low affinity but not a high affinity form of rat heart cyclic AMP phosphodiesterase. The concentrations of isoproterenol required to produce inhibition of the isolated enzyme were 10,000 to 100,000 fold larger than those required to produce a positive chronotropic response in the isolated atria. Another beta adrenergic receptor agonist, soterenol, had no effect on any of the isolated forms of the enzyme. Theophylline produced inhibition of low and high affinity forms of phosphodiesterase at the same concentrations required to produce a positive chronotropic response in the isolated atria. Results from two experimental models failed to reveal any circumstances under which a contribution to the positive chronotropic response could result from isoproterenol-induced inhibition of cyclic AMP phosphodiesterase.
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PMID:Studies on the inhibition by beta adrenergic receptor agonists of cyclic AMP phosphodiesterase activity of rat heart. 2 97

Behavioral sensitization of the gill-withdrawal reflex of Aplysia is the result of a prolonged increase in transmitter release from the presynaptic terminals of sensory neurons. Earlier work suggested that this presynaptic facilitation might be mediated by a serotonin-sensitive adenylate cyclase in the sensory neuron terminals. Here we present evidence that presynaptic facilitation results from a cyclic AMP-dependent increase in the calcium current that underlies action potentials in the sensory neurons. The action potentials of sensory neuron cell bodies have, in addition to a sodium current, a calcium current that is enhanced by blocking the opposing potassium current with tetraethylammonium. Under these conditions, the action potentials show a slowly repolarizing plateau that follows the Nernst potential for a calcium electrode and serves as a sensitive assay for changes in calcium current. Stimulation of the pathway that mediates sensitization, incubation with serotonin or phosphodiesterase inhibitors, or intracellular injection of cyclic AMP produces an increase in the calcium plateau in the presence of tetraethylammonium. In addition, both before and after sensitizing stimulation, the duration of the plateau potential parallels transmitter release as measured by the amplitude of monosynaptic excitatory postsynaptic potentials evoked in the motor neurons by intracellular stimulation of single sensory neurons. These results are consistent with the idea that presynaptic facilitation is caused by a cyclic AMP-mediated increase in a voltage-sensitive calcium current in sensory neuron presynaptic terminals. This synaptic action is novel in that it can produce little or no change in the resting potential, is of long duration, and exerts its influence directly on a conductance triggered by the action potential, rather than on non-voltage-sensitive conductances, as is typical of conventional synaptic actions.
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PMID:Presynaptic modulation of voltage-dependent Ca2+ current: mechanism for behavioral sensitization in Aplysia californica. 2 27

The glutamine synthetase (EC 6.3.1.2) from the N2-fixing bacterium Azotobacter vinelandii was purified to homogeneity by heat treatment, ammonium sulfate precipitation and ion-exchange chromatography. The following molecular parameters were determined: molecular weight 640 000, subunit molecular weight 53 000, partial specific volume 0.710 cm3/g, isoelectric point 4.6, amino acid composition. Most of the molecules are composed of 12 identical subunits but active oligomers of other degrees of polymerization, apparently aggregates with 8, 10 and 24 subunits, were also detected to a lesser extent. The enzymatic activity is regulated via adenylylation-deadenylylation cycles: liberation of AMP was detected upon treatment of the adenylylated form with phosphodiesterase along with a change in the catalytic properties. Adenylylation in vivo is specifically induced by high extracellular ammonia levels. The Km values for the Mg2+-dependent formation of glutamine were independent of the degree of adenylylation for glutamate and ATP, but varied for ammonia. Furthermore the catalytic activity is regulated by several nitrogenous feedback inhibitors. The degree of inhibition in some cases was dependent on the substrate concentrations: the sensitivity towards glycine, alanine and serine decreased with a decreasing ammonia level, while the sensitivity towards ADP or AMP increased with a decreasing ATP concentration. Part of the enzyme (about 30%) seems to be attached to the plasma membrane while the main fraction is found in the cytosol.
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PMID:The glutamine synthetase from Azotobacter vinelandii: purification, characterization, regulation and localization. 2 57

The differentiation of rat liver lysosomal acid phosphatase, acid ATPase, acid phosphodiesterase, acid ribonuclease, and acid deoxyribonuclease was studied by isoelectric focusing. To prevent autolytic digestion, inhibitors of cathepsins and neuraminidase were used. The proportion of acidic forms of acid phosphatase, acid ATPase and acid phosphodiesterase was increased by the use of extraction medium containing 0.05% Triton X-100. To investigate the identity of acid ATPase and acid phosphodiesterase, the relative activities among the multiple forms of these enzymes, the acid phosphodiesterase/acid ATPase ratio at each activity peak, and the degree of enzyme inhibition by p-chloromercuriphenyl sulfonic acid were estimated. The results suggest that acid ATPase is not identical with acid phosphodiesterase. With extraction medium free of Triton X-100, acid ribonuclease appeared in two forms. However, in addition to these forms, a new form of this enzyme with a more acidic pI (4.22) emerged when extraction medium containing 0.05% Triton X-100 was used. The major peak of acid deoxyribonuclease with pI=8.40-9.39 was obtained regardless of the extracting method.
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PMID:An isoelectric focusing study of acid phosphohydrolases in rat liver lysosomes. 2 87


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