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)

Digestion of tRNA by electrophoretically pure phosphodiesterase is limited to a short sequence of nucleotides at the 3'-terminus. On the average, four percent of all nucleotides can be released from tRNA. The optimum Mg2 concentration is 10mM and the optimum pH 9.2. The mode of action is a random attack by the enzyme on the substrate. The terminal AMP is completely removed at 15 degrees C after short incubation; about 400 mol of AMP were removed per min by 1 mol of enzyme. The following CMP residues are released much more slowly; at 15 degrees C incompletely, and at 37 degrees C more or less completely in 1 h. In about 50% of the tRNA molecules, the fourth nucleotide could be removed in very long incubations or with very high enzyme concentrations.
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PMID:Limited hydrolysis of tRNA by phosphodiesterase. 0 Feb 96

The effect of propranolol, phentolamine, papaverine, theophyline and Ca++, administered in different combinations of their threshold doses, on the relaxing effect of adrenaline was studied on an isolated segment of proximal jejunum of male cats. It was established that phentolamine weakened the relaxing effect of adrenaline, while propranolol had no effect on it. Papaverine potentiated the relaxinf effects of adrenaline both when administered alone and in combination with propranolol or with phentolamine. Theophylline weakened the relaxing effect of adfrenaline and of the combination phentolamine-adrenaline. Ca++ increased the smooth-muscle tone. The interpretation of the results obtained leads to the fundamental conclusions that the relaxing effect of adrenaline on cat jejunum is more alpha- than beta-adrenergically determined and that the system of the cyclic AMP participates in its realization. At the smae time, however, the possibility of participation of other mechanisms is not excluded. The smooth-muscle effect of papaverine and theophylline is not determined only by their inhibitory effect on phosphodiesterase.
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PMID:On the mechanism of the relaxing adrenaline effect on cat jejunum. 0 68

The effect of hypobaric hypoxia on the activities of glutamine synthetase, glutaminase and cyclic 3'5' AMP phosphodiesterase in rat brain was studied after exposure to 25,000' for 6 h. Glutamine synthetase activity was increased in all the regions of brain studied, and addition of gamma amino butyric acid, serotonin and cortisol in vitro produced a differential response. Glutaminase activity decreased in the whole brain. Cyclic 3'5' AMP phosphodiesterase activity decreased in cerebellum, medulla, hypothalamus and pituitary showing an accumulation of cyclic 3'5' AMP in these regions. The results suggest that glutamine synthesis and degradation are regulated in the central nervous system by cyclic AMP and cortisol: Gamma aminoburyric acid and other compounds can modulate the activity of glutamine synthetase and glutaminase.
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PMID:Glutamine synthetase, glutaminase and phosphodiesterase activities in brain under hypoxia: in vitro effect of cortisol, GABA and serotonin on glutamine synthetase. 0 63

(1) A system is described for studying the short-term effects of agents on proinsulin synthesis in vitro, as measured by the incorporation of [3H]leucine into isolated proinsulin. (2) Of the agents tested, glucose has the most marked, and apparently earliest, effect on proinsulin synthesis. (3) The adenyl cyclase system participates in the regulation of proinsulin synthesis since exogenous cyclic AMP, glucagon, and caffeine are stimulatory. When cyclic AMP is added to the medium in the presence of glucose, it is the most potent agent acting on the adenyl cyclase-phosphodiesterase system. (4) The addition of NADPH to isolated rat islets inhibits proinsulin and Bulk Protein synthesis in vitro.
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PMID:Regulation of proinsulin synthesis in isolated rat islets. 0 29

A clinical study was conducted to evaluate the role of PGs (prostaglandins) and cyclic AMP in the regulation of the contractility and pharmacologic reactivity of guinea pig and human ovaries in vitro. Ovarian contractility results with the various substances tested are graphed. Imidazole, acetylcholine, phenylephrine PGF2alpha, and methyl PGF2alpha increased ovarian contractility of guinea pig and human ovaries in vitro. Aminophylline suppressed this effect. Indomethacin inhibited ovarian contractions. PGF2alpha and its methyl derivative reversed this inhibitory effect of indomethacin. PGE2 decreased the amplitude and frequency of the spontaneous and PGF2alpha-induced contractions. The effect of certain of the substances was dose-dependent. The study results show that aminophylline, a phosphodiesterase inhibitor, is a potent relaxant of guinea pig ovary contraction in vitro. This inhibitory effect is probably caused by the accumulation of cyclic AMP. The ovarian activation caused by imidazole, on the other hand, is probably caused from an increased rate of cyclic AMP destruction. Thus, compounds interfering with cyclic AMP and PG metabolism effect ovarian contractility in vitro.
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PMID:Effects of aminophylline, imidazole and indomethacin on spontaneous and prostaglandin induced ovarian contractions in vitro. 0 82

The Lubrol-dispersed guanylate cyclase from sea urchin sperm was purified and isolated essentially free of detergent by GTP affinity chromatography, DEAE-Sephadex chromatography, and gel filtration. After removal of the detergent, the enzyme remained in solution in the presence of 20% glycerol. The specific activity of the purified enzyme was about 12 mumol of guanosine 3':5'-monophosphate (cyclic GMP) formed - min-1 - mg of protein-1 at 30 degrees, an activity about 4600 times that of a soluble guanylate cyclase purified recently from Escherichia coli (Macchia V., Varrone, S., Weissbach, H., Miller, D.L., and Pastan, I. (1975) J. Biol. Chem. 250, 6214-6217). The cyclic GMP phosphodiesterase activity was negligible and adenosine 3':5'-monophosphate (cyclic AMP) phosphodiesterase was not detectable in the purified preparation. Cyclic AMP formation from ATP occurred at a rate of 0.002% of that of guanylate cyclase. In the absence of phosphodiesterase or guanosine triphosphatase inhibitors, 100% of the added GTP was converted to cyclic GMP. The purified enzyme required Mn2+ for maximum activity, the relative rates in the presence of Mg2+ or Ca2+ being less than 0.6% of the rates with Mn2+. The purified enzyme displayed classical Michaelis-Menten kinetics with respect to MnGTP (apparent Km is approximately equal to 170 muM) in contrast to the positively cooperative kinetic behavior displayed by the unpurified, detergent-dispersed, or particulate guanylate cyclase. The molecular weight of the purified enzyme was approximately 182,000 as estimated on Bio-Gel A-0.5m columns equilibrated in the presence or absence of 0.1 M NaCl. The unpurified, detergent-dispersed enzyme also migrated with an apparent molecular weight of 182,000 on columns equilibrated with 0.5% Lubrol WX and 0.1 M NaCl, but it migrated as a large aggregate (molecular weight is greater than 5 X 10(5)) on columns equilibrated in the absence of either the detergent of NaCl. After gel filtration, the unpurified, dispersed enzyme still yielded positive cooperative kinetic patterns as a function of MnGTP. Na dodecyl-SO4 gel electrophoresis of the enzyme after the DEAE-Sephadex or the gel filtration steps resulted in two major protein bands with estimated molecular weights of 118,000 and 75,000. Whether or not these protein bands represent the subunit molecular weights of guanylate cyclase is unknown at present.
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PMID:Sea urchin sperm guanylate cyclase. Purification and loss of cooperativity. 0 69

The long-term regulation of fatty acid synthetase and acetyl-CoA carboxylase and of fatty acid and sterol synthesis was studied in C-6 glial cells in culture. When theophylline (10(-3) M) was added to the culture medium of these cells, rates of lipid synthesis from acetate and activities of synthetase and carboxylase became distinctly lower than in cells that were untreated. This effect appeared after approximately 12 h, and after 48 h enzymatic activities were reduced approx. 2-fold and rates of lipid synthesis from acetate 3- to 4-fold. The likelihood that the decrease in fatty acid synthesis from acetate was caused by the decrease in activities of fatty acid synthetase and acetyl-CoA carboxylase was established by several observations. These indicated that the locus of the effect probably did not reside at the level of acetate uptake into the cell, alterations in acetate pool sizes or conversion of acetate to acetyl-CoA. Moreover, de novo fatty acid synthesis was found to be the predominant pathway in these glial cells, whether treated with theophylline or not. The mechanism of the effect of theophylline on fatty acid synthetase was shown by immunochemical techniques to involve an alteration in content of enzyme rather than in catalytic efficiency. The change in content of fatty acid synthetase was shown by isotopic-immunochemical experiments to involve a decrease in synthesis of the enzyme. The mechanism whereby theophylline leads to a decrease in lipogenesis and in the synthesis of fatty acid synthetase may not be mediated entirely by inhibition of phosphodiesterase and an increase in cyclic AMP levels, because dibutyryl cyclic AMP (10(-3) M) only partially reproduced the effect.
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PMID:Long-term regulation by theophylline of fatty acid synthetase, acetyl-CoA carboxylase and lipid synthesis in cultured glial cells. 0 98

Histamine activated adenylate cyclase in pig skin (epidermal) slices, resulting in the accumulation of cyclic AMP. This effect was highly potentiated by the addition of cyclic AMP-phosphodiesterase inhibitors (theophylline, papaverine). A specific H2 receptor inhibitor (metiamide) inhibited the effect of histamine completely, while other antihistamines (diphenhydramine, acetophenazine, perphenazine, fluphenazine, promethazine) inhibited the effect of histamine to various lesser degrees. It has been shown that both epinephrine and prostaglandin E stimulate epidermal adenylate cyclase. Our data using specific blocking agents indicate that histamine, epinephrine and prostaglandin E2 act independently on the epidermal adenylate cyclase system.
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PMID:Histamine (H2) receptor-adenylate cyclase system in pig skin (epidermis). 0 11

The amounts of released soluble (s) antigen of influenza A/WSN virus were increased when the virus was allowed to interact with isolated plasma membranes in a medium containing substances enhancing the level of adenosine 3',5' cyclic monophosphate (c'AMP) or activating the enzyme adenylate cyclase. By contrast, less s-antigen was released upon addition to the incubation medium of foetal calf serum or calf serum proteins which activate c'AMP phosphodiesterase and thus decrease the level of c'AMP. Changes in the amount of released s-antigen were parallelled by changes in the activities of membrane Ca-adenosine triphosphatase and creatine phosphokinase.
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PMID:Interaction of plasma membranes with influenza virus. VI. The possible role of the adenylate cyclase system. 0 18

3',5'-Cyclic-AMP 5'-nucleotidohydrolase (cAMP phosphodiesterase, EC 3.1.4.17) was partial purified from metacercariae of Paragonimus africanus. The enzyme activity absolutely depends on Mg2 or Mn2+. The pH-optimum of the cAMP phosphidiesterase was found at pH 8.0. The Michaelis constant for cAMP was determined to be 5 X 10(-6) M. Papaverine deoxyadenosine, theophylline and adenosine were found to be competitive inhibitors of the enzyme activity. The inhibitor constants were calculated to be 13 X 10(-6)M, 25 X 10(-5)M, and 35 X 10(-5)M, and 85 X 10(-5)M,respectively. The molecular weight of the cAMP phosphodiesterase was estimated to be about 40 000 by gel filtration.
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PMID:Properties of 3',5'-cyclic-AMP phosphodiesterase from Paragonimus africanus metacercariae. 1 Jun 55


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