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:3.1.3.5 (5'-nucleotidase)
3,167 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

After partial hepatoectomy of the rat normal liver a maximum three-fold increase in the activity of alkaline phosphatase is observed in the blood serum, on the second-third day, and by the 14th day becomes almost normal; the activity of adenosine desaminase, AMP-aminohydrolase and 5'-nucleotidase becomes 30-60% as high for one-two days. The activity of the alkaline phosphatase in the liver becomes four times as high and reaches normalcy by the sixth day. The activity of adenosine desaminase and AMP-aminohydrolase increases to a less extent for a fortnight. The activity of 5'-nucleotidase decreases in the first day, then rises and a fortnight later becomes normal. After partial hepatoectomy of the liver injured with deoxicholic acid the activity of all the enzymes in blood serum anr a longer period of time; in the 5'-nucleotidase activity there is no initial drop and its earlier subsequent increase is observed.
...
PMID:[Enzyme activity in the regeneration process after partial hepatectomy of normal liver and that injured with deoxycholic acid]. 66 48

The characteristics of 5'-nucleotidase in a clonal line (C6) of rat glioma cells has been examined in detail. The cells liberated 6.80 +/- 0.33 mumol of inorganic phosphate/mg of cell protein/hour, producing nearly equimolar amounts of adenosine and inorganic phosphate from AMP in the extracellular fluid. No 5'-nucleotidase was released by the cells into the medium. Most of the 5'-nucleotidase activity was found to be located in the outer surface of the plasma membrane of C6 cells and rapidly accessible to exogenous AMP, by experiments based upon differential labeling of extracellular and intracellular compartments with 32P and 33P. The ecto-enzyme was active in the absence of divalent cations. However, Mn2+ or Co2+ were somewhat stimulatory. Zn2+ suppressed activity very markedly. The relationship of enzymatic reaction velocity to pH was complex, with an optimum at pH 7.4 for all substrates tested. The ecto-5'-nucleotidase readily hydrolyzed 5'-AMP and 5'-UMP. Other 5'-nucleoside monophosphates, including 5'-deoxy-AMP, were also hydrolyzed, but more slowly; 2'- or 3'-nucleoside monophosphates were not attacked. The ecto-5'-nucleotidase in the intact cell obeyed Michaelis-Menten kinetics. Apparent Km for AMP was 0.22 mM; apparent Km values for other substrates were similar and ranged from 0.16 to 0.18 mM. ADP exerted a very powerful inhibitory effect, behaving as a competitive inhibitor, and 5'-UMP behaved as a strictly competitive substrate for 5'-AMP. ATP and ITP were inhibitory. Of these, ITP served to increase Km for AMP. ATP did likewise, but also greatly lowered Vmax. These findings indicate that the intact cell is capable of rapid hydrolysis of exogenous 5'-AMP, to produce adenosine at the cell surface at a rate which responds directly to extracellular AMP concentration but which can be suppressed by extracellular ADP or ATP.
...
PMID:Ecto-5'-nucleotidase of intact cultured C6 rat glioma cells. 81 33

The finite life-span of fibroblasts in culture may reflect aging at the cellular level and gout is clinical condition whose incidence also increases with age. In order to better understand the age-related changes in purine metabolism, activities of purine degrading (adenosine deaminase and 5'-nucleotidase) and reutilizing (adenine phosphoribosyltransferase, hypoxanthine phosphoribosyl-transferase and adenosine kinase) enzymes were measured in serially cultured skin fibroblasts from normal subjects and from gouty patients who overproduce uric acid. Serially cultured fibroblasts from gouty overproducers of uric acid displayed increased purine enzyme levels with increasing cell passage while fibroblasts from normal donors showed little change in activity. There was no alteration in relative degrading and reutilizing enzyme levels. The data suggest an increase in the rate of purine turnover in aging gouty fibroblasts compared with normal fibroblasts.
...
PMID:Activities of purine pathway enzymes in gouty human fibroblasts aged in vitro. 83 27

To examine the potential participation of the plasma membrane in differentiation, we studied the enzymatic activities of 5'-nucleotidase and adenylate cyclase as a function of chondrocyte maturation. 16-day-old chick embryo tibiae epiphyses were dissected into proliferative, growing and hypertrophying zones. Partially purified membrane fractions prepared by differential centrifugation from the respective tissue segments were assayed for enzymatic activity. Cell suspensions from the same segments were examined cytochemically for the presence of 5'-nucleotidase. The findings show that the 5'-nucleotidase activity of the chick embryo epiphyseal cartilage has the following characteristics: (a) it has a Km of about 25 muM for 5'AMP, and is inhibited by a mixture of 2' and 3'AMP (apparent Ki about 10(-4) M) and by AOPCP; (b) it is predominantly localized at the cell surface but is also detected in the cytoplasm and in association with nuclear heterochromatin; and (c) it increases 10-fold (on a DNA basis) during the maturation of the epiphyseal cartilage cells. The adenylate cyclase activity has these characteristics: (a) it does not change during chondrocyte maturation (on a DNA basis); (b) its susceptibility to adenosine inhibition decreases at least 10-fold. The implication of these findings relative to a possible role of adenosine in cellular communication is discussed.
...
PMID:Membrane changes during cartilage maturation. Increase in 5'-nucleotidase and decrease in adenosine inhibition of adenylate cyclase. 83 6

Electrophoresis of red cell pyrimidine 5'-nucleotidase was carried out on cellulose acetate strips. One major band of activity was found in preparations from human erythrocytes. This enzyme showed a specificity for the pyrimidine nucleotides UMP and CMP. No activity was detected with AMP. Pyrimidine 5'-nucleotidase activity could be separated from that of acid phosphatase with the use of alpha-glycerophosphate. This method may be useful in the study of pyrimidine 5'-nucleotidase deficiency in red cells.
...
PMID:Electrophoretic characterization of pyrimidine 5'-nucleotidase of human erythrocytes and its distinction from acid phosphatase. 89 Sep 45

Perfused rat hearts catalyze the hydrolysis of AMP added to the perfusion fluid at a rate of 35 mumol/g dry weight/min. The activity is specific for 5'-nucleoside monophosphates, little activity being observed with 2' and 3'-AMP. The enzyme exhibits Michaelis-Menten kinetics in situ and is inhibited competitively by adenosine-5'-alpha, beta-methylene diphosphonate (Ki = 13 muM). This, as well as the nucleotide specificity, confirms that the hydrolysis is catalyzed by 5'-nucleotidase. The maximum activity of 5'-nucleotidase in perfused hearts is equal to or greater than that found in heart homogenates; thus, all of the enzyme is accessible to AMP added externally. Hydrolysis of endogenous AMP was studied in the perfused heart. Under aerobic conditions hearts contain very low amounts of purine nucleosides, and little or no nucleoside is found in the effluent perfusate. Under anaerobic conditions hearts accumulate adenosine, inosine, and hypoxanthine and release all three substances into the perfusate. Hydrolysis of externally added AMP was also observed in perfused skeletal muscle and liver, at rates of 10 and 17 mumol/g dry weight/min, respectively.
...
PMID:Studies of 5'-nucleotidase in the perfused rat heart. Including measurements of the enzyme in perfused skeletal muscle and liver. 97 76

In this study we report that preincubation of Dictyostelium discoideum membrane-bound adenylate cyclase with ATP over the concentration range 0.5 to 100 mM results in a loss of catalytic activity and that this effect persists even after removal of ATP. An analysis of the time course of this effect shows that, at 25 mM ATP, a 5- to 10-min preincubation results in 50% loss of activity. Additional studies on this effect showed that anhydride bond cleavage of ATP occurs during the preincubation. However, loss of catalytic activity is not porduced by ADP, AMP, cAMP, adenosine, pyrophosphate, or phosphate either separately or in pairs. Further, using the structural analogs adenosine 5'-(alpha, beta-methylene)triphosphate and adenyl-5'-yl imidodiphosphonate, we show that there is a direct correlation between alpha-beta-phosphoanhydride bond cleavage and the loss of catalytic activity. These results can be interpreted in terms of two classes of reaction mechanisms: either those involving covalent modifications or those involving a ligand-induced slow conversion of the adenylate cyclase from an active to an inactive form. Additional studies show that the addition of AMP to the reaction mixture, as well as removal of the membrane-bound 5'-nucleotidase activity, can prevent the loss of cyclase activity. These results suggest not only that adenylate cyclase activity is related to the AMP:ATP ratio but that the cyclase activity can be modified by the level of 5'-nucleotidase activity. Studies on the duration of the loss of activity produced by ATP show that following removal of ATP and additional incubation, a gradual recovery of cyclase activity is observed. This result suggests that under appropriate conditions the cyclase inactivation by ATP is reversible.
...
PMID:Time-dependent changes in Dictyostelium discoideum adenylate cyclase activity upon incubation with ATP. 98 25

Mouse resident peritoneal macrophages display sufficient 5'-nucleotidase activity to hydrolyze 58 nm AMP/min per cell protein. This activity increases approximately 163 nm AMP/min per mg after 72 h in culture. The enzyme is renewed in unstimulated cells with a half-time of 13.9 h. The activity is not reduced by treatment of intact cells with a variety of proteolytic enzymes, including trypsin, pronase, urokinase, and plasmin. Cells obtained from an inflammatory exudate have diminished or absent levels of enzyme activity. Endotoxin-elicited cells display enzyme activitiy of 20.9 nm AMP/min per mg, while thioglycollate-stimulated macrophages have no detectable activity. The reduced level of activity in endotoxin-stimulated cells is due to their elevated rate of enzyme degradation, with a half-time of 6.9 h. Their rate of enzyme synthesis is essentially normal. No evidence for latent enzyme activity could be obtained in thioglycollate-stimulated cells, nor do these cells produce any inhibition of normal cell enzyme activity. Serum deprivation reduces the enzyme activity of resident cells to about 45% of control activity. These conditions do not significantly affect the rate of enzyme synthesis, but again are explainable by an increase in the rate of enzyme degradation. Pinocytic rate is elevated in endotoxin-stimulated cells which show a more rapid rate of enzyme degradation than unstimulated cells do. However, in serum-free conditions, the rate of enzyme degradation is doubled with no change in the pinocytic rate of the cells.
...
PMID:5'-Nucleotidase activity of mouse peritoneal macrophages. I. Synthesis and degradation in resident and inflammatory populations. 100 5

1. The hypoxanthine/guanine and adenine phosphoribosyltransferase activities in a wide variety of human tissues were studied during their growth and development from foetal life onward. A wide range of activities develop after birth, with especially high values in the central nervous system and testes. 2. Postnatal development of hypoxanthine/guanine phosphoribosyltransferase was also defined in the rat. Although there were increases in the central nervous system and testes, there was also a rise in activity in the liver, which was less marked in man. 3. A sensitive radiochemical assay method, using dTTP to inhibit 5'-nucleotidase activity, suitable for tissue extracts, was developed. 4. No definite evidence of the existence of tissue-specific isoenzymes of hypoxanthine/guanine or adenine phosphoribosyltransferase was found. Hypoxanthine/guanine phosphoribosyltransferase in testes, however, had a significantly different thermal-denaturation rate constant. 5. The findings are discussed in an attempt to relate activity of hypoxanthine/guanine phosphoribosyltransferase to biological function. Growth as well as some developmental changes appear to be related to increase in the activity of this enzyme.
...
PMID:Developmental changes in purine phosphoribosyltransferases in human and rat tissues. 101 39

The 5'-phosphomonoesterase activity of 5'-nucleotidase (EC 3.1.3.5) and alkaline phosphatase (EC 3.1.3.5) participates in the catabolism of purine ribonucleotides to uric acid in humans. Initial velocity studies of 5'-nucleotidase suggest a sequential mechanism of interaction between AMP nad MgCl2, with a Km of 14 and 3 muM, respectively. With product inhibition studies the apparent Ki's for adenosine, inosine, cytidine, and inorganic phosphate were 0.4, 3.0, 5.0, and 42 mM, respectively. A large number of nucleoside mono-, di-, and tri-phosphate compounds were inhibitors of the enzyme. Allopurinol ribonucleotide, ADP, or ATP were competitive inhititors when AMP was the substrate, with a Ki slope of 120 muM. The phosphomonoesterase activity of human placental microsomal alkaline phosphatase had a pH optimum of 10.0 and had only 18% of maximum activity at pH 7.4. Substrates and inhibitors included almost any phosphorylated compound. The Km for AMP was 0.4 mM and the apparent Ki for Pi was 0.6 mM. Activity was increased only 19% by 5 mM MgCl2. These observations suggest that 5'-nucleotidase and alkaline phosphatase may be inhibited by ATP and Pi, respectively, under normal intracellular conditions, and that AMP may be preferentially hydrolyzed by 5'-nucleotidase.
...
PMID:Purine catabolism in man: inhibition of 5'-phosphomonesterase activities from placental microsomes. 101 16


<< Previous 1 2 3 4 5 6 7 8 9 10 Next >>

---