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

Leukemic cells incubated in vitro with 2'-deoxyadenosine (dAdo) plus an inhibitor of adenosine deaminase, 2'-deoxy-coformycin (DCF), show different metabolic responses depending on the histologic and immunologic type of the leukemia. Leukemic cells were obtained from 54 patients with acute lymphoblastic leukemia (ALL), 9 with myeloid or nonlymphoblastic leukemia, 3 with chronic lymphocytic leukemia (CLL), and 3 with lymphoma. There was a wide variation in the LD50, the concentration of dAdo that caused 50% inhibition of the incorporation of 3H-thymidine into cells in the presence of 20 microM DCF. T-cell leukemia specimens were much more sensitive to dAdo than were specimens of pre-B-ALL and null-ALL. In leukemic cells that had been incubated with 14C-dAdo plus DCF, a good correlation was observed between the LD50 and the ratio of 14C-deoxyATP to ATP (correlation coefficient for the fit to a hyperbola = 0.853). The accumulation of deoxyATP by the leukemic cell specimens was correlated best with the activity of ecto-ATPase, less well with cytoplasmic 5'-nucleotidase and deoxyadenosine kinase, and poorly with adenosine deaminase and ecto-5'-nucleotidase. The clinical response to DCF therapy of a patient with T-ALL and another with pre-B-ALL was consistent with the in vitro metabolic response of their cells to DCF and dAdo.
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PMID:Biochemical correlates of the differential sensitivity of subtypes of human leukemia to deoxyadenosine and deoxycoformycin. 628 41

Treatment of the C6 glioblastoma cell with trinitrobenzenesulfonic acid (TNBS) resulted in the selective inactivation of ecto-5'-nucleotidase under conditions which maintained cell viability. Cells respond to ecto-enzyme inactivation by replacing 80% of lost activity within 24 hrs. A lag time of 4-6 hrs before ecto-5'-nucleotidase replacement began and its complete blockage by cycloheximide indicated that the source of replaced enzyme was de novo synthesis and not an intracellular pool. Release of 5'-nucleotidase activity into culture medium in the form of membraneous vesicles slowed during the active recovery period and then steadily increased with time as the plasma membrane enzyme level approached normal. TNBS did not exert a direct inhibitory action upon the exfoliative process as release of vesicular GM1 and protein were little affected. Decrease in exfoliated 5'-nucleotidase activity may be due to a selective conservation of the enzyme in the exfoliative process.
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PMID:Ecto-5'-nucleotidase regeneration after chemical modification of the plasma membrane. 630 49

Inactivation of both cytosolic 5'-nucleotidase and ecto-5'-nucleotidase by diethylpyrocarbonate indicated the presence of an essential histidyl residue which in the cytosolic enzyme was conclusively located at the active site. Inactivation by thiol reagents indicated the presence of an essential cysteinyl residue in both enzymes. The data suggest that both 5'-nucleotidases belong to a group of histidine phosphatases which also includes glucose-6-phosphatase and acid phosphatase. A working hypothesis for the catalytic mechanism of these enzymes is proposed.
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PMID:Identification of histidyl and cysteinyl residues essential for catalysis by 5'-nucleotidase. 632 Dec 42

Lymphocytes from three infants with reticuloendotheliosis and eosinophilia ( Omenn 's syndrome) and immunodeficiency were assayed for 5'-nucleotidase activity. B and T lymphocytes from all three patients were totally deficient in ecto-5'-nucleotidase activity, but had normal levels of cytoplasmic 5'-nucleotidase. In contrast, cultured lymphocytes expressed normal ectoplasmic and cytoplasmic activities, suggesting that the lymphocyte-restricted enzyme deficiency was not likely a primary genetic defect. The deficiency of lymphocyte ecto-5'-nucleotidase was not associated with any abnormality of deoxynucleoside metabolism. The absence of lymphocyte ecto-5'-nucleotidase may be a characteristic feature of this syndrome and may help to distinguish this disease from others with similar manifestations.
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PMID:Absence of lymphocyte ecto-5'-nucleotidase in infants with reticuloendotheliosis and eosinophilia (Omenn's syndrome). 632 96

After immunization with purified human placental ecto-5'-nucleotidase and fusion, 18 different hybrids were obtained which produce an antibody inhibitory for enzyme activity. These antibodies show complete cross-reactivity with the enzyme in a membrane-bound form or on the surface of intact cells. After cloning and ascites production, the antibody of one clone ( IFH - 5N1 ) was studied in greater detail. The IFH - 5N1 antibody is of the IgG 1 subclass. Optimal enzyme inhibition is 90% for purified 5'-nucleotidase and 80% for the enzyme on lymphoblasts. The specificity of this antibody is further demonstrated by enzyme inhibition assays and fluorescence labeling using various 5'-nucleotidase-positive and -negative human cells such as peripheral blood lymphocytes, leukemic cells, lymphoblastoid B- and T-cell-lines and fibroblasts. The antibody should provide a useful tool for the diagnosis of certain forms of acute leukemias and for the study of normal human lymphocyte subpopulations.
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PMID:Development and properties of a monoclonal antibody specific for human ecto-5'-nucleotidase. 632 7

Rabbit antibodies specific to sarcolemma of cardiomyocytes have been studied for their effect on activity of 5'-nucleotidase ecto-enzyme of the Wistar rat cardiomyocytes. It is shown that incubation of isolated plasma membranes of cardiomyocytes of rats (100 micrograms of protein) with the gamma-globulin fraction of antisarcolemmal cardial serum (gamma-ASCS, 20 micrograms protein) and with the gamma-globulin fraction of normal rabbit serum (gamma-NRS, 0.20 micrograms protein) promotes a decrease of the enzyme activity. An inhibiting effect was greatly pronounced in incubation with gamma-NRS and did not depend on the dose of antibodies and duration of their action. An assumption is made that inhibiting action of antibodies on activity of ecto-5'-nucleotidase may change adenosine concentration and may be one of elements in the mechanism promoting an increase of the intracellular calcium concentration.
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PMID:[Effect of antibodies specific to sarcolemma of cardiomyocytes in activity of 5-nucleotidase in rats]. 751 52

Ecto-5'-nucleotidase catalyses the hydrolysis of AMP at the surface of a variety of cells whereas it is absent from others. In addition to its catalytic activity, a function in neural development and also its interaction with extracellular matrix proteins has been reported. In order to further elucidate the biological function of ecto-5'-nucleotidase we have investigated the effect of 5'-nucleotidase on nerve growth factor-induced differentiation of PC12 cells. Furthermore, we compared the effect of an inhibitory versus a non-inhibitory monospecific antibody against the enzyme on neuritic differentiation and survival of PC12 cells that constitutively express the enzyme. When coverslips are coated with the soluble form of ecto-5'-nucleotidase in addition to collagen, there is a considerable increase in nerve growth factor-induced neurite length during the first 24 h of culture. Addition of an antibody to a culture medium that inhibits 5'-nucleotidase activity to 33% of control values dramatically reduces the number of neurites per cell within 3 days of culture. The cells round up, cluster and eventually die. On the contrary, another antibody that had no significant effect on enzyme activity affected neither nerve growth factor-induced neurite formation nor survival of PC12 cells. Addition of adenosine (200 nM, 10 or 20 microM) to the culture medium did not influence PC12 cell differentiation. The effects induced by the inhibitory antibody could be only partially prevented by simultaneous application of adenosine. Our results suggest that 5'-nucleotidase is essential for nerve growth factor-induced neurite outgrowth and survival of PC12 cells.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:5'-nucleotidase activates and an inhibitory antibody prevents neuritic differentiation of PC12 cells. 758 90

Although dipyridamole has been extensively studied as an anti-aggregating agent, its mechanism of action has not been elucidated. Cultured mesangial cells were treated with dipyridamole 1-100 microM from 6-72 h. Ecto-5'-nucleotidase activity approximately doubled (from 115 +/- 11 to 226 +/- 14 nmol/min/mg) after treatment with 100 microM dipyridamole for 72 h. This effect was concentration- and time-dependent. Cycloheximide, an inhibitor of protein synthesis, did not alter basal 5'-nucleotidase activity. However, it prevented stimulation by 5 microM dipyridamole. Adenosine availability at the receptor sites was increased by dipyridamole and S-(p-nitrobenzyl)-6-thioinosine (NBTI), which inhibit adenosine uptake into the cell. Addition of dipyridamole or NBTI to the adenosine-treated mesangial cells produced an additive increase in ecto-5'-nucleotidase activity. Dipyridamole, through its effect on extracellular adenosine and ecto-5'-nucleotidase, may have an influence upon regulation of the glomerular microcirculation.
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PMID:Effect of dipyridamole on glomerular mesangial cell ecto-5'-nucleotidase expression. 795 70

Ecto-5'-nucleotidase (5'-ribonucleotide phosphohydrolase, EC 3.1.3.5) of mesangial cells may be the main source of adenosine within the glomerulus, and thus essential in the regulation of glomerular microcirculation. c-AMP and c-AMP-stimulating agents were found to induce ecto-5'-nucleotidase of mesangial cells. Dopamine is a catecholamine known to increase c-AMP levels in mesangial cells. We have studied the effect of dopamine on ecto-5'-nucleotidase expression and DNA synthesis of glomerular mesangial cells in culture. Human mesangial cells were exposed to dopamine in the concentration range from 0.1 microM- to 1 mM, for 6-72 h. Ecto-5'-nucleotidase activity of human mesangial cells increased from 118.6 +/- 7.7 to 171 +/- 12 nmol/min/mg in a 72 h culture. This effect was time- and dose-dependent. Cycloheximide, an inhibitor of protein synthesis did not modify basal 5'-nucleotidase activity but it suppressed the stimulatory effect of 10 microM dopamine. DNA synthesis of human mesangial cells, studied after exposure of these cells to the same concentrations of dopamine used in the 5'-nucleotidase stimulation, was inhibited, being also dose dependent. These results indicate that dopamine induces ecto-5'-nucleotidase and inhibits DNA synthesis of cultured human mesangial cells. This action of dopamine on glomerular mesangial cells may be important in the regulation of glomerular hemodynamics.
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PMID:Effect of dopamine on ecto-5'-nucleotidase expression in human glomerular mesangial cells. 800 38

Adenosine may be protective in acute vascular injury by inhibiting platelet aggregation and neutrophil oxidant release. In contrast, adenine nucleotides, which may be released with acute vascular injury, stimulate platelet aggregation and neutrophil oxidant release. Ectonucleotidases, membrane enzymes that catabolize extracellular nucleotides, are the primary mechanism for degrading circulating nucleotides to adenosine. Ecto-5'-nucleotidase converts extracellular AMP to adenosine. We hypothesized that endothelial cell injury alters ecto-5'-nucleotidase activity. Using a novel assay first reported by Jamal et al. (Biochem J 250: 369-373, 1988) with rat adipocytes, we studied the properties of ecto-5'-nucleotidase in intact monolayers of cultured bovine pulmonary artery endothelial cells (BPAEC) and examined the effect of endotoxin on enzyme activity. The assay uses a fluorescent analog of AMP, 1,N6-etheno-AMP (E-AMP), as the substrate for ecto-5'-nucleotidase, and measures ethenoadenosine (E-Ado) formation. Etheno-AMP in Hepes buffer, pH 7.4, at 22 degrees, was added to confluent monolayers of BPAEC; samples of supernatant were collected after various intervals, and E-AMP and E-Ado were quantitated by HPLC. Using these methods we found a Km of 15 +/- 6 microM, a pH optimum of 7.48, minimal effect of MgCl2 or CaCl2 at physiologic pH, and inhibition by alpha,beta-methylene ADP, a known 5'-nucleotidase inhibitor. We established that the monolayer assay was indeed measuring cell surface associated 5'-nucleotidase. To determine the effect of endotoxin, we incubated confluent monolayers with endotoxin in Minimal Essential Medium plus 10% fetal bovine serum for 24 hr, washed them, and assessed the conversion of E-AMP to E-Ado by the endotoxin-injured cells. Endotoxin stimulated endothelial ecto-5'-nucleotidase activity. This increase in 5'-nucleotidase activity in response to endotoxin injury may represent an important clearance mechanism for circulating adenine nucleotides and may be protective in acute vascular injury by increasing adenosine production.
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PMID:A simple assay for ecto-5'-nucleotidase using intact pulmonary artery endothelial cells. Effect of endotoxin-induced cell injury. 824 Mar 97


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