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)

4-Nitrophenyl and 2-napthyl monoesters of phenylphosphonic acid have been synthesized, and an enzyme catalyzing their hydrolysis was resolved from alkaline phosphatase of a commerical calf intestinal alkaline phosphatase preparation by extensive ion-exchange chromatography, chromatography on L-phenylalanyl-Sepharose with a decreasing gradient of (NH4) 2SO4, and gel filtration. Detergent-solubilized enzyme from fresh bovine intestine was purified after (NH4)2SO4 fractionation by the same technique. The purified enzyme is homogeneous by polyacrylamide gel electrophoresis and sedimentation equilibrium centrifugation. It has a molecular weight of 108,000, contains approximately 21% carbohydrate, and has an amino acid composition considerably different from that reported from alkaline phosphatase from the same tissue. The homogeneous intestinal enzyme, an efficient catalyst of phosphonate ester hydoolysis but not of phosphate monoester hydrolysis, was identified as a 5'-nucleotide phosphodiesterase by its ability to hydrolyze 4-nitrophenyl esters of 5'-TMP but not of 3'-TMP. Also consistent with this identification was the ability of the enzyme to hydrolyze 5'-ATP to 5'-AMP and PPi, NAD+ to 5'-AMP and NMN, TpT to 5'-TMP and thymidine, pApApApA to 5'-AMP, and only the single-stranded portion of tRNA from the 3'-OH end. Snake venom 5'-nucleotide phosphodiesterase also hydrolyzes phosphonate esters, but 3'-nucleotide phosphodiesterase of spleen and cyclic 3',5'-AMP phosphodiesterase do not. Thus, types of phosphodiesterases can be conveniently distinguished by their ability to hydrolyze phosphonate esters. As substrates for 5'-nucleotide phosphodiesterases, phosphonate esters are preferable to the more conventional esters of nucleotides and bis(4-nitrophenyl) phosphate because of their superior stability and ease of synthesis. Furthermore, the rate of hydrolysis of phosphonate esters under saturating conditions is greater than that of the conventional substrates. At substrate concentrations of 1 mM the rates of hydrolysis of phosphonate esters and of nucleotide esters are comparable and both superior to that of bis(4-nitrophenyl) phosphate.
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PMID:Hydrolysis of phosphonate esters catalyzed by 5'-nucleotide phosphodiesterase. 17 Sep 64

Plasma membranes from 6 spontaneously metastasizing and 4 non-metastasizing rat mammary carcinomata were isolated by discontinuous sucrose density gradient centrifugation of microsomal pellets. The starting microsomal fraction contained 40-50% plasma membranes as determined by the levels of 5'-nucleotidase activity, with a negligible amount of nuclear (1%), mitochondrial (5%) and lysomal (7%) contamination. Five distinct fractions (F1-F5) were banded at densities 1 X 09, 1 X 13, 1 X 15, 1 X 17 and 1 X 21 at 25 degrees C, in addition to a pellet (F6) obtained by centrifuging at 76,000 g for 17 h. The fractions F1 through F5, all contained various concentrations of membranous structures, while the pellet (F6) contained only amorphous materials as evidenced by electron microscopy. The F3 fraction at the gradient 1 X 15 had the highest specific as well as total activity of the plasma membrane marker enzyme, with aggregates of the least contaminated plasma membranes in vesicular forms. This fraction also had the lowest specific activity for glucose-6-phosphatase (smooth ER marker) and for beta-D-glucuronidase (lysomal marker), and therefore was considered to be the "cleanest" plasma membrane fraction. When the activity of 4 additional plasma membrane marker enzymes, i.e., alkaline phosphatase, phosphodiesterase I, nucleotide pyrophosphatase and alkaline ribonuclease was determined in the same F3 fraction, their levels were significantly lower in every metastasizing tumour than in the non-metastasizing ones, with the enzyme activity decreasing in direct proportion to the metastasizing capacity. On the other hand, the marker enzymes were high in all non-metastasizing tumours, with the activity seemingly increasing with the immunogenicity of tumour cells. There was no significant difference between the 2 groups of mammary tumours in the levels of sialic acid, hexosamine, phospholipid or cholesterol in the plasma membranes. Thus, the level of plasma membrane marker enzymes is considered an accurate indicator for metastasizing capacity in the rat mammary tumour system.
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PMID:Plasma membrane associated enzymes of mammary tumours as the biochemical indicators of metastasizing capacity. Analyses of enriched plasma membrane preparations. 17 19

A protein acting as inhibitor of cyclic 3':5'-nucleotide phosphodiesterase (EC 3.1.4.1.) activity was found in the ox retina tissue. An inhibitor from one tissue (ox retina) effectively cross-inhibited a phosphodiesterase from another tissue (rat brain), indicating a lack of tissue specificity. Kinetic analysis showed that inhibition was independent of the time of preliminary incubation of the inhibitor with enzyme but dependent on its concentration in the reaction mixture. An inhibitor decreased the V of the enzyme and had no effect on its Km for cyclic adenosine-3':5'-monophosphate. The inhibitory effect was more pronounced with cyclic adenosine-3':5'-monophosphate than with cyclic guanosine-3':5'-monophosphate used as substrates of the reaction. The extractable form of the phosphodiesterase of the retina rod outer segments was much more sensitive to the inhibitory action than the membrane-bound one. The binding of labeled cyclic adenosine-3':5'-monophosphate to the inhibitory protein was shown not to occur. The inhibitor was sensitive to trypsin treatment, indicating that it was a proten attempt was mode to purify the inhibitory factor. Gel filtration indicated that the inhibitor had a molecular weight of 38 000.
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PMID:Protein inhibitor of cyclic adenosine 3':5'-monophosphate phosphodiesterase in retina. 17 72

In tissue culture experiments, cells derived from glioma 26, a transplantable tumor of C57B1/6 mice, were sensitive to both floxuridine (5-fluorodeoxyuridine) and 5-fluorodeoxyuridine-5'-(5-iodo-3-indolyl)phosphate, an enzyme-mediated drug activated by 5'-nucleotide phosphodiesterase. When these compounds were tested on the tumor in animals at a level of 5 mg/kg for 5 days, tumor growth was inhibited approximately 20% by both compounds. When higher levels of 5-fluorodeoxyuridine, 100 mg/kg four times weekly throughout the lifespan of the mouse, were given, the tumor, although inhibited at first, developed resistance and continued to grow until it killed the animal. Phosphodiesterase levels in the tumor rose as the tumor grew. On the other hand, thymidine kinase levels dropped as anticipated from the known 5-fluorodeoxyuridine-resistant hepatoma tissue culture data. This enzyme pattern was maintained in transplantable mouse glioma lines established from the resistant tumors. One of these lines, tested at a level of 5 mg/kg for 5 days, showed no response to 5-fluorodeoxyuridine but was still sensitive to 5-fluorodeoxyuridine-5'-(5-iodo-3-indolyl) phosphate. These experiments, therefore, offer a model system and a rationale for the design and study of more compounds that could be activated by the enzyme phosphodiesterase. Such compounds might be used alternatively when resistance to 5-fluorodeoxyuridine develops, a common clinical experience in the use of this anticancer drug.
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PMID:5'-nucleotide phosphodiesterase activity of floxuridine-resistant mouse glioma. 17 49

The localization of cyclic 3', 5'-nucleotide phosphodiesterase activity at the neuromuscular junction and in skeletal muscle of the newt was studied cytochemically. In the axon terminal, activity was localized to a site on the membranes of synaptic vesicles. In skeletal muscle, activity occurred in the sarcoplasmic reticulum but was restricted to the longitudinal tubules. Junctional folds of the motor end plate were unreactive. These findings are suggestive of a role of cyclic AMP in the functions of synaptic vesicles and sarcoplasmic reticulum and indicate its effects are terminated at these sites.
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PMID:Cytochemical localization of cyclic 3', 5'-nucleotide phosphodiesterase activity in the neuromuscular junction and skeletal muscle of the newt. 17 8

The activity of cyclic 3':5'-nucleotide phosphodiesterase (PDE) (EC 3.1.4.17) was measured in cultured normal and neoplastic rat mammary epithelium. Total PDE activity in normal cells was 1.6 to 6 times higher than that in tumor cells over a concentration range of 0.01 to 1 mM cyclic adenosine 3':5'-monophosphate. PDE activity was distributed between the low-speed (4000 x g) particulate and supernatant fractions in both cell lines, with the particulate fraction possessing 60 to 70% of the total. Double reciprocal kinetic plots were nonlinear, suggesting the presence of high- and low-affinity PDE activities. Similar, but not identical biphasic curves obtained from both normal and neoplastic cells suggested that at least two different PDE activities were present in a membrane-bound as well as a soluble form. Apparent Michealis constants for the high-affinity enzyme ranged from 2 to 6 muM; the low-affinity enzyme was 1 mM. In the presence of 10 mM caffeine and at a substrate concentration of 1 muM, PDE activity was inhibited 40 and 80% of basal levels in normal and tumor cells, respectively. In general, the membrane-bound enzyme was inhibited to a greater extent than the soluble, regardless of the cell line examined. Although normal cells exhibited higher PDE activities in terms of total specific activity, when soluble activities were compared at low substrate concentrations, the opposite was the case. At a substrate concentration of 0.01 muM, normal cell, low-Km soluble specific activity was 40% less than comparable tumor cell activity. Our results support the contention that PDE is induced by its own substrate, cyclic adenosine 3':5'-monophosphate. In addition, they suggest that the low cyclic adenosine 3':5'-monophosphate steady-state levels characteristic of malignant cells are maintained by a soluble high-affinity isozyme of PDE.
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PMID:Cyclic nucleotide phosphodiesterase activity in normal and neoplastic rat mammary cells grown in monolayer culture. 17 39

Viable mutants of simian virus 40 (SV40), with deletions ranging in size from 15 to 200 base pairs, have been obtained by infecting CV-1P cells with circularly permuted linear SV40 DNA. The linear DNA was produced by cleavage of closed circular DNA with DNase I in the presence of Mn2+, followed, in some cases, by mild digestion with lambda 5'-exonuclease. The SV40 map location and the size of each deletion were determined by using the S1 nuclease mapping procedure (Shenk et al., 1975) and the change in size of fragments produced by Hind II + III endonuclease cleavage. Deletions in at least three regions of the SV40 chromosome have slight or no effect on the rate or yield of viral multiplication and on vira-induced cellular transformation. These regions are located at the following coordinates on the SV40 physical map: 0.17 to 0.18; 0.54 to 0.59; and 0.68 to 0.74.
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PMID:Construction and analysis of viable deletion mutants of simian virus 40. 17 2

In adult albino rats, increased sentivity of the organism to insulin action caused by systematic muscular exercises preserved in conditions of adrenergic blockade but was reduced by theophylline administration (inhibition of 3'-5'-AMP-phosphodiesterase activity). The sensitivity to insulin action 3'-5'-phosphodiesterase (in muscles, liver, and adipose tissue) increased during adaptation to muscular activity. Simultaneously the insulin inactivation in muscle and liver tissues also increased.
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PMID:[Analysis of an increase in the body's sensitivity to insulin]. 17 1

Changes in cyclic-3', 5'-nucleotide phosphodiesterase activity of the peripheral blood leukocytes were investigated in patients with bronchial asthma. Leukocyte phosphodiesterase activity was significantly elevated during asthmatic attacks. Elevated activity was seen in most active asthmatics irrespective of the drug treatment. The ratio of the adenyl cyclase activity to the phosphodiesterase activity of the same leukocyte decreased to less than 1.0 during asthmatic attacks.
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PMID:Leukocyte cyclic-3', 5'-nucleotide phosphodiesterase activity in human bronchial asthma. 18 72

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


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