Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.1.3.5 (5'-nucleotidase)
 3,167 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

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

Similarities between lead-induced anemia and a new hereditary erythorenzymopathy involving pyrimidine-specific 5'-nucleotidase prompted studies of the effects of lead on this and other erythrocyte enzymes. In vitro incubations of normal mature erythrocytes demonstrated that significant inhibition of pyrimidine 5'-nucleotidase occurred in the presence of lead at concentrations that had minimal effects on many other erythrocyte enzymes assayed simultaneously. Similarly, subjects with chronic lead intoxication secondary to industrial exposure exhibited substantial and consistent impairment of erythrocyte pyrimidine-5'-nucleotidase activity. Results suggest that lead-induced deficiency of this enzyme in maturing erythroid elements could, if sufficiently severe, result in induction of basophilic stippling and premature erythrocyte hemolysis analogous to that encountered in the genetically induced enzyme-deficiency syndrome.
 ...
PMID:Effects of low-level lead exposure on pyrimidine 5'-nucleotidase and other erythrocyte enzymes. Possible role of pyrimidine 5'-nucleotidase in the pathogenesis of lead-induced anemia. 118 42

Both erythrocytes and leukocytes from a patient with erythrocyte pyrimidine 5'-nucleotidase (P5N) deficiency were shown to contain increased amounts of pyrimidine nucleotides. These findings suggested that the leukocytes were also deficient for P5N. Measurement of the P5N activity in lysates from lymphocytes or granulocytes, in the presence of inhibitors for non-specific 5'-nucleotidase or alkaline phosphatase, indeed showed a deficiency for P5N in lymphocytes and granulocytes of the patient with erythrocyte P5N deficiency. However, the P5N deficiency in the leukocytes did not cause clinical disturbances in addition to the weak haemolytic anaemia.
 ...
PMID:Deficiency of pyrimidine 5'-nucleotidase in human leukocytes. 255 46

Recently cytochemical evidence has been presented for a novel enzyme activity, i.e. 'manganese-dependent pyrimidine 5'-nucleotidase (MDPNase)' activity in the rod outer segments (ROS) of rat retinas in situ and in isolated rat ROS. The present biochemical study was undertaken to seek further evidence for this enzyme activity using an independent method. A series of enzyme assays was carried out to test for MDPNase activity in Triton extracts of rat ROS isolated by sucrose density gradient centrifugation. Hydrolysis of the substrate, cytidine-5'-monophosphate, was measured spectrophotometrically and expressed as microgram of released inorganic phosphorus hr-1 mg-1 protein in the sample. The results showed that the ROS extracts contained enzyme activity (18.1 +/- 3.8) that was increased 5-6-fold (102.3 +/- 10.6) in the presence of 7.4 mM MnCl2. The enzyme activity was not enhanced by Mg2+ ions (19.0 +/- 7.7) and was strongly inhibited by 10-20 mM NaF (11.8 +/- 2.9). Assays for substrate specificity revealed that the Mn2+-stimulated phosphatase activity was specific for 5'-nucleotides. Pyrimidine nucleotides (5'-CMP and 5'-UMP) were the preferred substrates. Comparison of enzymatic hydrolysis of 5'-CMP and 5'-AMP over a pH range from 4.5 to 8.0 revealed that at acid pH, the majority of the observed 5'-nucleotidase activity (82% at pH 5.0, 58% at pH 5.5) was manganese dependent, whereas at neutral pH and above, most of the enzyme activity was unaffected by the presence of Mn2+ ions.(ABSTRACT TRUNCATED AT 250 WORDS)
 ...
PMID:Biochemical evidence for Mn2+-dependent 5'-nucleotidase activity in isolated rod outer segments. 282 95

A simple method for determining pyrimidine 5'-nucleotidase (P5N) activity in whole blood has been developed, inhibiting the plasma activity for UMP-hydrolysis by concanavalin (Con A). Con A specifically inhibits the activity of plasma 5'-nucleotidase (5N) but does not affect erythrocyte P5N activity. The anticoagulant EDTA partially inhibits 5N activity but slightly activates P5N. P5N activity determined by the present method with heparinised blood and Con A was comparable with that by the method reported previously and correlated well with blood lead concentrations. The mean value and SD for P5N activity in normal subjects (n = 72) not exposed to lead are 16.2 and 2.5 mumole/h/g Hb, respectively. The present method can eliminate not only the isolation step of RBC but also Hb determination, the activity being expressed as mumole/h/l blood or RBC. Thus the procedures are so simplified that the assay may be used as a routine test for mass screening of lead exposure.
 ...
PMID:Determination of pyrimidine 5'-nucleotidase (P5N) activity in whole blood as an index of lead exposure. 284 Jan 10

Erythrocytes from patients with hereditary pyrimidine 5'-nucleotidase (P5N, EC 3.1.3.5) deficiency accumulate large quantities of several pyrimidine nucleotides and their derivatives. In addition, the reduced glutathione (GSH) concentration is elevated in erythrocytes from patients with this enzyme deficiency. In the present study, we were unable to demonstrate any effect of various pyrimidine nucleotides and their derivatives on enzymes of glutathione biosynthesis and metabolism. Thus, elevation of GSH levels in erythrocytes from P5N patients is not a result of modulation of these enzymes by pyrimidine nucleotides and their derivatives.
 ...
PMID:Pyrimidine nucleotides do not affect the enzymes of glutathione biosynthesis. 286 97

The fluoropyrimidine deoxyribonucleotide 5-fluoro-2'-deoxyuridine 5'-monophosphate (FdUMP) was encapsulated in human erythrocytes by a procedure based on hypotonic hemolysis and isotonic resealing. Encapsulated FdUMP (up to 9 mumol/ml of packed erythrocytes) did not affect erythrocyte metabolism or morphology. Hemolysates were found to catalyze efficient dephosphorylation of FdUMP to yield nearly stoichiometric amounts of the corresponding deoxyribonucleoside 5-fluoro-2'-deoxyuridine (FdUrd), an antineoplastic drug showing selective cytotoxicity toward liver metastases from colorectal carcinomas. The dephosphorylation reaction had an apparent Km of 7.7 +/- 1.2 mM FdUMP at pH 7.4 and was remarkably slower at pH 8.2. ATP, GTP, and UTP inhibited both the disappearance of FdUMP and the formation of FdUrd in hemolysates. The enzyme responsible for the FdUMP-to-FdUrd conversion was identified with the deoxyribonucleotide-specific isozyme of erythrocyte pyrimidine 5'-nucleotidase (EC 3.1.3.5). Intracellular formation and subsequent release of FdUrd were observed in intact erythrocytes loaded with FdUMP. Inhibition of FdUrd release from these erythrocytes was obtained by raising the pH intracellularly and, alternatively, by coencapsulation of ATP. Autologous FdUMP-loaded erythrocytes might be used as endogenous bioreactors designed for time-programmed and liver-targeted delivery of FdUrd.
 ...
PMID:Conversion of encapsulated 5-fluoro-2'-deoxyuridine 5'-monophosphate to the antineoplastic drug 5-fluoro-2'-deoxyuridine in human erythrocytes. 296 99

We report a rapid and reproducible assay for activity of human erythrocyte pyrimidine 5'-nucleotidase and deoxypyrimidine 5'-nucleotidase. The nucleotides CMP, UMP, dUMP, dCMP or dTMP are individually incubated 30 min at 37 degrees C with erythrocyte hemolysate and 4 mM magnesium chloride in Tris, pH 7.5. Data are provided for standardization of the reaction with each substrate. Individual nucleoside products are assayed in less than 10 min by reversed-phase high-performance liquid chromatography at 280 nm with 0-14% methanol in 0.01 M potassium dihydrogen phosphate. This is the first report of a high-performance liquid chromatographic assay system which allows quantitation of the activity of pyrimidine 5'-nucleotidase isozymes using five individual pyrimidine and deoxypyrimidine nucleotides as the substrates.
 ...
PMID:Assay of human erythrocyte pyrimidine and deoxypyrimidine 5'-nucleotidase by isocratic reversed-phase high-performance liquid chromatography. 298 6

The activities of three erythrocyte (rbc) enzymes, arginase, pyrimidine 5'-nucleotidase (P5N), and deoxypyrimidine 5'-nucleotidase (dP5N), were compared in 16 lead workers and 14 age matched controls as correlates of blood lead (PbB) and unextracted zinc protoporphyrin (EP) concentrations. Subjects with PbB of 0.9-2.5 microM (19-52 micrograms/dl) had 6.5 +/- 0.6 IU of P5N activity with uridine monophosphate (UMP) as substrate, significantly less (p less than 0.001) than the 12.0 +/- 0.7 IU activity of controls with PbB 0.3-0.6 microM (6-12 micrograms/dl). The mean activity of rbc dP5N with either deoxyuridine monophosphate (dUMP) or thymidine monophosphate as substrate, and of rbc arginase, did not differentiate the two groups. The correlation coefficients of ln PbB with the selected substrates for P5N and dP5N were: UMP, r = -0.75; dUMP, r = -0.61; TMP, r = -0.23. The correlation coefficient of ln PbB and arginase activity was -0.03. Rbc P5N (UMPase) is a significant correlate of PbB, equivalent to rbc protoporphyrin. HPLC assay of rbc UMPase activity is a sensitive and rapid assay that appears to meet criteria for a reliable clinical laboratory index of blood lead concentrations.
 ...
PMID:Erythrocyte arginase, pyrimidine 5'-nucleotidase (P5N), and deoxypyrimidine 5'-nucleotidase (dP5N) as indices of lead exposure. 301 77

The method for determining erythrocyte pyrimidine 5'-nucleotidase (P5N EC 3.1.3.5) activity has been simplified using an automated high performance liquid chromatograph (HPLC). The activity determined by the simplified method agreed closely with that obtained by conventional methods. In 161 lead workers P5N activity declined linearly with increasing blood lead concentrations (Pb-B) between 20 and 80 micrograms/100 g, and correlated well with Pb-B (r = -0.87). For the same group of workers, correlation coefficients between Pb-B v ALA-D activity, zinc protoporphyrin, ALA-U, and coproporphyrin were -0.87, 0.73, 0.70, and 0.32, respectively. At Pb-B greater than or equal to 40 micrograms/100 g, the validity of P5N (1.86 at a cut off of 10 less than or equal to units) was higher than that of other indicators examined. P5N activity was fairly stable during the storage of samples for two weeks at 4 degrees C. Determination of P5N activity by this method may be a useful indicator in screening for moderate exposure to lead.
 ...
PMID:A simplified method for determining erythrocyte pyrimidine 5'-nucleotidase (P5N) activity by HPLC and its value in monitoring lead exposure. 302 35


1 2 3 Next >>