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)

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.
...
PMID:On the mechanism of the relaxing adrenaline effect on cat jejunum. 0 68

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.
...
PMID:Properties of 3',5'-cyclic-AMP phosphodiesterase from Paragonimus africanus metacercariae. 1 Jun 55

The effects of various agents on the newly identified cyclic CMP phosphodiesterase (C-PDE) in crude extracts of a number of rat tissues and on the enzyme partially purified from the rat liver were examined. Papaverine and 1-methyl-3-isobutylxanthine were without effects on C-PDE at concentrations that inhibited up to 90% of cyclic AMP phosphodiesterase (A-PDE) and cyclic GMP phosphodiesterase (G-PDE) activities. When assayed using 1 micron substrates, theophylline inhibited C-PDE to a lesser extent than A-PDE and G-PDE. 2'-Deoxy cyclic AMP (specific A-PDE inhibitor) and 2'-deoxy cyclic GMP (specific G-PDE inhibitor) were relatively poor and non-specific inhibitors for C-PDE. Imidazole, while augmenting the high Km A-PDE and G-PDE from the liver but not from the heart, was without effect on the liver C-PDE but stimulated the heart C-PDE. Potassium phosphate was more specific in inhibiting C-PDE than A-PDE and G-PDE. The present findings suggest that C-PDE represents a potential site of specific pharmacological regulations, and that C-PDE may be a separate enzyme distinguishable from the purine cyclic nucleotide class of phosphodiesterases.
...
PMID:Effects of phosphodiesterase inhibitors, imidazole and phosphate on cyclic CMP phosphodiesterase are different from those on cyclic AMP and cyclic GMP phosphodiesterases. 8 41

Cyclic AMP and cyclic GMP phosphodiesterase activities (3' : 5'-cyclic AMP 5'-nucleotidohydrolase, EC 3.1.4.17) were demonstrated in the isolated intima, media, and adventitia of rabbit aorta. The activity for cyclic AMP hydrolysis in the intima was 2.7-fold higher than that for cyclic GMP hydrolysis. The activity for cyclic AMP hydrolysis in the media was approximately equal to that for cyclic GMP hydrolysis, but in the adventitia, cyclic GMP hydrolytic activity was 2.1-fold higher than cyclic AMP hydrolytic activity. Distribution of the activator of the phosphodiesterase was studied in the three layers. Each layer contained the activator. The activator was predominantly localized in the smooth muscle layer (the media). The effect of the activator and Ca2+ on the media cyclic AMP and cyclic GMP phosphodiesterase was also briefly studied. The activity of the cyclic GMP phosphodiesterase was stimulated by micromolar concentration of Ca2+ in the presence of the activator. However, the activity of the cyclic AMP phosphodiesterase was not significantly stimulated by Ca2+ up to 100 muM in the presence of the activator. Above 90% of cyclic nucleotide phosphodiesterase activity in the whole aorta was found to be derived from the media. A major portion (60-70%) of the media enzyme was found in 105 000 times g supernatant. Cyclic AMP phosphodiesterase in the supernatant was partially purified through Sepharose 6B column chromatography and partially separated from cyclic GMP phosphodiesterase. Using a partially purified preparation from the 105 000 times g supernatant the main kinetic parameters were specified as follows: 1) The pH optimum was found to be about 9.0 using Tris-maleate buffer. The maximum stimulation of the enzyme by Mg2+ was achieved at 4mM of MgC12. 2) High concentration of cyclic GMP (0.1 mM) inhibited noncompetitively the enzyme activity, and the activity was not stimulated at any tested concentration of cyclic GMP. 3) Activity-substrate concentration relationship revealed a high affinity (Km equals 1.0 muM) and low affinity (Km equals 45 muM) for cyclic AMP. The homogenate and 105 000 times g supernatant of the media also showed non-linear kinetics similar to the Sepharose 6B preparation and their apparent Km values for cyclic AMP hydrolysis were 1.2 muM and 36-40 muM and an enzyme extracted by sonication from 105 000 times g precipitate also exhibited non-linear kinetics (Km equals 5.1 muM and 70 muM). 4) Papaverine exhibited much stronger inhibition on the aorta cyclic AMP phosphodiesterase (50% inhibition of the intima enzyme, I5 o at 0.62 muM, I5 o of the media at 0.62 muM and I5 o of the adventitia at 1.0 muM) than on the brain (I5 o at 8.5 muM) and serum (I5 o at 20 muM) cyclic AMP phosphodiesterase, while theophylline inhibited these enzymes similarly. However, cyclic GMP phosphodiesterases in all tissues examined were inhibited similarly, not only by theophylline but also by papaverine.
...
PMID:Cyclic 3',5'-AMP phosphodiesterase of rabbit aorta. 16 19

Quantitative studies of the action of theophylline and papaverine were performed in rat epididymal fat pads, both on the lipolytic effect and on the activity of phosphodiesterase, adenylate cyclase and protein kinase. Papaverine, a stronger inhibitor of phosphodiesterase than theophylline, did not produce lipolysis. The maximum lipolytic effect (glycerol release) of theophylline was much higher than that of epinephrine and nearly approached the effect exerted by dibutyryl cyclic AMP. While theophylline potentiated or was without any effect on lipolysis produced by epinephrine and dibutyryl cyclic AMP, papaverine at concentration 10- minus 3 M reduced the effect of both drugs as well as of theophylline by 90 per cent. These concentrations of papaverine also strongly inhibited the activity of adenylate cyclase. Neither papaverine nor theophylline prevented the activation of protein kinase by cyclic AMP. The data suggest that the lack of a lipolytic effect of papaverine migth be caused by a combination of its inhibitory effect on adenylate cyclase and direct inhibition of activation of triglyceride lipase.
...
PMID:The absence of stimulation of lipolysis by papaverine, a strong inhibitor of phosphodiesterase. 16 81

There are phosphodiesterase activities in both particulate and supernatant fractions which hydrolyze guanosine 3',5'-cyclic monophosphate (cGMP) and adenosine 3',5'-cyclic monophosphate (cAMP) with an apparent Km of 2-8 muM and with an apparent Km of 44-222 muM. 4-(3-Butoxy-4-methoxybenzyl-2-imidazolidinone (RO20-1724) did not inhibit cGMP phosphodiesterase activity in homogenates of mouse neuroblastoma cells, but markedly inhibited cAMP phosphodiesterase activity. Papaverine and theophylline inhibited both cGMP and cAMP phosphodiesterase activities to about the same extent. The former was more potent than the latter. The specific activity of cGMP phosphodiesterase as a function of protein concentrations first increased and then decreased. The specific activity of cAMP phosphodiesterase decreased under a similar experimental condition.
...
PMID:Differences and similarities between guanosine 3',5'-cyclic monophosphate phosphodiesterase and adenosine 3',5'-cyclic monophosphate phosphodiesterase activities in neuroblastoma cells in culture. 16 81

Mitochondrial, microsomal and soluble fractions separated from the guinea pig taenia and from the dog longitudinal smooth muscle were used as phosphodiesterase preparation. Each preparation had low and high Km values, indicating the existence of at least two kinds of phosphodiesterase. Papaverine and Aspaminol (1, 1-diphenyl-3-piperidinobutanol hydrochloride), hydralazine, caffeine Na benzoate and aminophylline were used at test drugs. Aspaminol had little inhibitory effect on phosphodiesterase. Ki value of papaverine almost equalled the concentration (M) which was necessary to produce 50% relaxation. Relaxation of the guinea pig taenia by papaverine was preceded by an increase of intracellular cyclic AMP,. Therefore, the action of papaverine is likely to be mediated by an increase in cyclic AMP, which is caused by inhibition of the phosphodiesterase-catalyzed breakdown of cyclic AMP. There was little correlation between relaxing activities of the drugs used and their antiphosphodiesterase activities. Relaxation of the smooth muscle induced by the smooth muscle relaxants excepting papaverine is not due to inhibition of phosphodiesterase.
...
PMID:Antiphosphodiesterase activity and nonspecific smooth muscle relaxation tested on intestinal smooth muscles. 16 24

Essential differences in the degree of papaverine [5 x 10(-5) M]- and theophylline [1 x 10(-3) M]-induced inhibition of cyclic nucleotide phosphodiesterase (PDE) were found in homogenates from different structures of the CNS as well as from different organs of male albino rats. Both inhibitors of PDE showed a mosaic pattern of their inhibitory effects on the enzyme activity of the brain structures tested. Papaverine inhibited PDE by 36 percent in the spinal cord, 53 percent in the cerebellum, 56 percent in the cortex, and 75 percent in the brain stem. Theophylline inhibited PDE least in the cerebellum (26 percent ) and most markedly in the brain stem (68 percent). Still larger differences were observed in the inhibitory action of papaverine and theophylline on PDE of the organs tested (e.g., papaverine inhibited PDE by 6 percent in the heart and 73 percent in the spleen; theophylline inhibited PDE by 26 percent in the adrenals and by 72 percent in the heart. The mosaic sensitivity of PDE in different organs and brain structures to papaverine and theophylline was considered as an expression of isoenzyme heterogeneity.
...
PMID:Differential inhibition of phosphodiesterase according to the organ origin of the enzyme. 17 Aug 1

Actions of various methylxanthines (theophylline, theobromine, caffeine) and papaverine, i.e. drugs which are known to inhibit phosphodiesterase (PDE), were studied on the basal and stimulated synthesis of corticosterone in vitro by using rat adrenal slices. When slices were incubated with methylxanthines, the synthesis of corticosterone was slightly increased. The order of potency, expressed as the efficacy (intrinsic activity) was: theophylline greater than caffeine greather than theobromine. Papaverine did not stimulate the synthesis. The synthesis stimulated by ACTH or the dibutyryl derivative of c-AMP (DBA) was reduced by all of the inhibitors of phosphodiesterase. The molar concentration of the inhibitors which reduced the stimulated steroidogenesis by 50% was lowest for papaverine, higher for theobromine and theophylline and highest for caffeine. Papaverine was active in concentrations of about 10(-5)M, while the methylxanthines were effective in concentrations of 10(-3)--10(-2)M. When the PDE-inhibitors were added to the incubate simultaneously with the stimulant (ACTH or DBA), there was a delay of 60 min before the synthesis was completely blocked. When the stimulant was added 30 min before the administration of an inhibitor, the inhibitory action was no more evident. The inhibitory action of theophylline, but not that of papaverine, was reversed by washing adrenal slices free from the inhibitor, before adding the stimulant. The type of inhibition for papaverine as well as for methylxanthines in antagonizing both the ACTH- and DBA-stimulated synthesis of corticosterone was not competitive but of a mixed type.
...
PMID:Actions of various methylxanthines and papaverine on the synthesis of corticosterone in vitro. 17 Sep 47

Human blood platelet contained at least three kinetically distinct forms of 3': 5'-cyclic nucleotide phosphodiesterase (3': 5'-cyclic-AMP 5'-nucleotidohydrolase, EC 3.1.4.17) (F I, F II, and F III) which were clearly separated by DEAE-cellulose column chromatography. Although a few properties of the platelet phosphodiesterases such as their substrate affinities and DEAE-cellulose profile resembled somewhat those of the three 3': 5'-cyclic nucleotide phosphodiesterase in rat liver reported by Russell et al. [10], there were pronounced differences in some properties between the platelet and the liver enzymes: (1) the platelet enzymes hydrolyzed both cyclic nucleotides and lacked a highly specific cyclic guanosine 3': 5'-monophosphate (cyclic GMP) phosphodiesterase and (2) kinetic data of the platelet enzymes indicated that cyclic adenosine 3': 5'-monophosphate (cyclic AMP) and cyclic GMP interact with a single catalytic site on the enzyme. F I was a cyclic nucleotide phosphodiesterase with a high Km for cyclic AMP and a negatively cooperative low Km for cyclic GMP. F II hydrolyzed cyclic AMP and cyclic GMP about equally with a high Km for both substrates. F III was low Km phosphodiesterase which hydrolyzed cyclic AMP faster than cyclic GMP. Each cyclic nucleotide acted as a competitive inhibitor of the hydrolysis of the other nucleotide by these three fractions with Ki values similar to the Km values for each nucleotide suggesting that the hydrolysis of both cyclic AMP and cyclic GMP was catalyzed by a single catalytic site on the enzyme. However, cyclic GMP at low concentration (below 10 muM) was an activator of cyclic AMP hydrolysis by F I. Papaverine and EG 626 acted as competitive inhibitors of each fraction with virtually the same Ki value in both assays using either cyclic AMP or cyclic GMP as the substrate. The ratio of cyclic AMP hydrolysis to cyclic GMP hydrolysis by each fraction did not vary significantly after freezing/thawing or heat treatment. These facts also suggest that both nucleotides were hydrolyzed by the same catalytic site on the enzyme. The differences in apparent Ki values for inhibitors such as cyclic nucleotides, papaverine and EG 626 would indicate that three enzymes were different from each other. Centrifugation in a continuous sucrose gradient revealed sedimentation coefficients F I and II had 8.9 S and F III 4.6 S. The molecular weight of these forms, determined by gel filtration on a Sepharose 6B column, were approx. 240 000 (F I and II) and 180 000 (F III). F III was purified extensively (70-fold) from homogenate, with a recovery of approximately 7%.
...
PMID:Human blood platelet 3': 5'-cyclic nucleotide phosphodiesterase. Isolation of low-Km and high-Km phosphodiesterase. 17 73


1 2 3 4 5 6 7 Next >>

---