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)

In an attempt to determine the metabolic defect causing severe combined immunodeficiency (SCID) in horses in which altered purine metabolism has been observed, various parameters of purine and pyrimidine metabolism were evaluated. The activities of nine purine enzymes (adenosine kinase, purine nucleoside phosphorylase, deoxyadenosine kinase, deoxycytidine kinase, 5'-nucleotidase, AMP deaminase, hypoxanthine-guanine phosphoribosyl transferase, and adenine phosphoribosyl transferase were measured in fibroblasts. All activities determined for SCID horses were normal. Uptake of 10 microM adenosine or 2'-deoxyadenosine (a growth inhibitory concentration for SCID fibroblasts) by SCID fibroblasts was identical to that found for normal fibroblasts in the presence of both 1 and 50 microM phosphate. The Km determined for the transport of both adenosine and 2'-deoxyadenosine was 35 microM. In the presence of p-nitrobenzylthioguanosine (a nucleoside transport inhibitor), 2'-deoxyadenosine uptake was inhibited to the same extent in all fibroblast lines tested. To determine if the last step in pyrimidine biosynthesis might be altered in SCID fibroblasts, UMP synthase activities were evaluated but found to be normal (0.5 nmol UMP formed/min/mg protein).
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PMID:Metabolic investigations of fibroblasts from horses, Equus caballus, with hereditary severe combined immunodeficiency. 299 78

The kinetic properties of highly purified human placental cytoplasmic 5'-nucleotidase were investigated. Initial velocity studies gave Michaelis constants for AMP, IMP, and CMP of 18, 30, and 2.2 microM, respectively. The enzyme shows the following relative Vmax values: CMP greater than UMP greater than dUMP greater than GMP greater than AMP greater than dCMP greater than IMP. The activity was magnesium-dependent, and this cation binds sequentially with a Km of 14 microM for AMP and an apparent Km of 6 mM for magnesium. A large variety of purine, pyrimidine, and pyridine compounds exert an inhibitory effect on enzyme activity. IMP, GMP, and NADH produce almost 100% inhibition at 1.0 mM. Nucleoside di- and triphosphates are potent inhibitors. ATP and ADP are competitive inhibitors with respect to AMP and IMP as substrates with Ki values of 100 and 15 microM, respectively. Inorganic phosphate is a noncompetitive inhibitor with Ki values of 19 and 43 mM. Nucleosides and other compounds studied produce only a modest decrease of enzyme activity at 1 mM. Our findings suggest that the enzyme is regulated under physiological conditions by the concentrations of magnesium, nucleoside 5'-monophosphates, and nucleoside di- and triphosphates. The nucleotide pool concentration regulates the enzyme possibly by a mechanism of heterogeneous metabolic pool inhibition. These properties of human placental cytoplasmic 5'-nucleotidase may be related to the control of nucleotide degradation in vivo.
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PMID:Human placental cytoplasmic 5'-nucleotidase. Kinetic properties and inhibition. 300 Oct 58

A simple method is presented for the determination of pyrimidine-5'-nucleotidase activity using a continuous spectrophotometric assay system. Activity is determined by measuring inorganic phosphate generation using a linked indicator system that produces uric acid in the presence of inosine, purine nucleoside phosphorylase, and xanthine oxidase. This method has several advantages over any of the methods currently in use.
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PMID:A continuous spectrophotometric assay for pyrimidine-5'-nucleotidase. 300 35

Purine and pyrimidine enzyme profiles of human cell lines have been investigated. A novel observation was the finding that most of the cell lines showed very low or undetectable levels of cytidine (deoxycytidine) deaminase, while they possessed pyrimidine 5'-nucleotidase, cytidine and deoxycytidine kinase activities. Most cell lines showed high levels of adenosine deaminase and purine nucleoside phosphorylase activities and low levels of purine 5'-nucleotidase. We propose that high adenosine deaminase and purine nucleoside phosphorylase activities and low cytidine deaminase activity may be of importance for immature hematopoietic cells in order to ensure a balanced synthesis of the DNA precursors.
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PMID:Low cytidine deaminase levels in human hematopoietic cell lines. 362 11

Haemolytic anaemia due to pyrimidine-5'-nucleotidase deficiency was favourably affected by splenectomy. The life-long haemolytic anaemia ended, but red cell deformability was reduced and the oxyhaemoglobin dissociation curve was normal.
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PMID:Haemolytic anaemia due to pyrimidine-5'-nucleotidase deficiency. 609 66

Pyrophosphate, p-nitrophenyl phosphate and a variety of pyrimidine and purine nucleotides are hydrolyzed by the solubilized membrane-bound enzymes of the brush border plasma membrane of Hymenolepis diminuta. The pH optima (or ranges) for hydrolysis of substrates are 8.0 (pyrophosphate), 8.8 (p-nitrophenyl phosphate), 8.4-8.9 (nucleoside monophosphates), and 7.1-8.1 (nucleoside triphosphates); all substrates, with the exception of nucleoside triphosphates, have a higher affinity for the solubilized enzyme at pH 7.4 than at their optimal pH for hydrolysis. ATP is degraded completely by the enzyme preparation to adenosine and inorganic phosphate, but since neither ADP nor ATP accumulate in the incubation medium it is not known whether ATP hydrolysis involves the sequential hydrolysis of terminal phosphate groups. Isoelectric focusing and various chromatographic procedures (gel permeation, ion-exchange and hydrophobic interaction chromatography) fail to separate the alkaline phosphatase, phosphodiesterase, 5'-nucleotidase, adenosine triphosphatase and ribonuclease activities associated with the solubilized membrane preparation. Additionally, inhibitor studies indicate that only a single enzyme with low substrate specificity is involved in the hydrolysis of nucleotides, p-nitrophenyl phosphate, pyrophosphate and hexose phosphate esters. Purines and pyrimidines and their nucleosides interact with the active site, and in some instances activity of the enzyme is stimulated by an unknown mechanism.
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PMID:Nucleotide hydrolysis by solubilized membrane-bound enzymes of the brush border plasma membrane of Hymenolepis diminuta. 613 88

All in vitro cell lines from Drosophila melanogaster do not possess measurable hypoxanthine - guanine - phosphoribosyltransferase (HGPRT) and 5'-nucleotidase activities. Nevertheless these enzymatic activities could be detected by the modification of culture conditions or treatment of crude extracts from Drosophila cells (1). A Drosophila melanogaster hemocyte line enabled demonstration of a relationship between the activities of HGPRT and 5'-nucleotidase. Only the addition of azaserine to the culture medium allows detection of a measurable amount of HGPRT and 5'-nucleotidase in cells devoid of endogenous synthesis of purine nucleotides. This action of azaserine suggests that the simultaneous expression of both enzymes is first directed by the suppression of the 5'-nucleotidase inhibition by pyrimidine nucleotides, and later on by the 5'-nucleotidase activity hydrolyzing the mononucleotides which inhibited the HGPRT, resulting its expression. This regulation system is confirmed by the simultaneous recovery of HGPRT and 5'-nucleotidase activities after heating cell cultures or cell extracts. Under such experimental conditions, 5'-nucleotidase is desensitized towards its negative effectors, while HGPRT regulation remains unchanged.
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PMID:Regulation of purine biosynthesis in cultured Drosophila melanogaster cells: II/relationships between hypoxanthine-guanine-phosphoribosyl transferase and 5'-nucleotidase. 616 Aug 79

Both the electrophoretic patterns and substrate specificity of the total 5'-nucleotidase activity at pH 7.4 in serum from 10 normal adults (19-49 years) were identical using various purine and pyrimidine mononucleotides as substrates. Different purified alkaline phosphatases were studied at the same time in the same manner. The serum enzymes showed substrate specificity qualitatively similar to that of the bovine liver enzyme. The electrophoretic study showed two fractions for both the liver enzyme and the serum enzymes with the different substrates, indicating that each of these are dephosphorylated by the same two, mutually different, enzyme molecules. Each of the other enzymes showed only a single fraction, which was identical for each enzyme with the various substrates.
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PMID:The 5'-nucleotidase activity in normal human serum. Electrophoretic patterns and substrate specificity. 624 70

Various purine and pyrimidine mononucleotides seem to be dephosphorylated by a 5'-nucleotidase complex composed of four fractions in sera from both patients with gall stones and from normal subjects. Agarose gel electrophoresis, with the addition of Triton X-100, demonstrated that the faster (F-) fraction of the enzyme complex and the slower (S-) fraction both consisted of two sub-fractions (termed alpha and beta). The enzyme complex showed a uniform substrate specificity pattern, which was independent of the absolute enzyme activity.
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PMID:The 5'-nucleotidase complex in sera from patients with gall stones--electrophoretic patterns and substrate specificity. 626 90

The activity of pyrimidine-5'-nucleotidase (P5N) (EC 3.1.3.5) was assayed in microsamples of rat blood using high performance liquid chromotography (HPLC). The assay is based on the measurement of enzymatically formed uridine in erythrocyte hemolysates (10-50 microliter) and produces a linear activity curve from 5 to 1000 microM/g Hb/h. Acute (22 h) administration of lead acetate ip to rats induced a dose-dependent inhibition of P5N activity in erythrocyte samples.
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PMID:HPLC analysis of erythrocyte pyrimidine-5'-nucleotidase inhibition by lead. 627 81


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