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)

We studied copper uptake from copper dihistidine complexes by plasma membrane vesicles isolated from rat liver and compared the data with those for uptake under the same conditions by hepatocytes cultured from rat liver to determine whether membrane vesicles can be used to study copper uptake. Marker enzyme analysis showed a 28-fold increase in 5'-nucleotidase activity, a slight increase in endoplasmic reticulum and no contamination with mitochondrial membranes. Copper uptake by vesicles is temperature dependent, and solubilization with Triton X-100 results in a loss of accumulative capacity. Increasing osmotic pressure resulted in a decrease in copper levels in the vesicles at equilibrium, showing that uptake--as opposed to binding by the vesicles--occurred. Uptake by vesicles is concentration dependent, with evidence for cooperation in the uptake sites. The substrate concentration yielding 10% maximum uptake was 4.01 +/- 0.5 mumol/L, maximum uptake was 10.8 +/- 0.4 nmol/Cu/mg protein.min and the n value was 1.5 +/- 0.2. In contrast, uptake by cells showed no cooperation (n = 1.09 +/- 0.06) and a significantly higher apparent Michaelis-Menten constant (17.4 +/- 1.3 mumol/L). As expected, the maximum uptake was lower in the hepatocytes (1.82 +/- 0.08 nmol/mg protein.min). Albumin, N-ethylmaleimide and zinc all inhibited uptake in vesicles and in hepatocytes, and the degrees of inhibition were similar in both types of preparation. Vitamin C stimulated uptake in both vesicles and hepatocytes; again, there was a correlation between the increase in uptake at different concentrations. However, cadmium inhibited uptake and nickel stimulated uptake in vesicles and neither metal had any effect in hepatocytes.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:A comparison of copper uptake by liver plasma membrane vesicles and uptake by isolated cultured rat hepatocytes. 792 4

5'-Nucleotidase, responsible for the conversion of adenosine-5'-monophosphate into adenosine, was purified from bovine brain membranes, and subjected to oxidative inactivation. The 5'-nucleotidase activity decreased slightly after the exposure to either glutathione or Fe2+. The glutathione-mediated inactivation of 5'-nucleotidase was potentiated remarkably by Fe2+, but not Cu2+, in a concentration-dependent manner. Similarly, glutathione exhibited a concentration-dependent enhancement of the Fe2+-mediated inactivation. In comparison, the glutathione/Fe2+ system was much more effective than the ascorbate/Fe2+ system in inactivating the enzyme. In support of an intermediary role of superoxide ions or H2O2 in the action of glutathione/Fe2+ system, superoxide dismutase and catalase expressed a substantial protection against the inactivation by the glutathione/Fe2+ system. Meanwhile, hydroxyl radical scavengers such as mannitol, benzoate or ethanol were incapable of preventing the inactivation, excluding the participation of extraneous hydroxyl radicals. Whereas adenosine 5'-monophosphate as substrate exhibited a modest protection against the glutathione/Fe2+ action, a remarkable protection was expressed by divalent metal ions such as Zn2+ or Mn2+. Structure-activity study with a variety of thiols indicates that the inactivating action of thiols in combination with Fe2+ resides in the free sulfhydryl group and amino group of thiols. Overall, thiols, expressing more inhibitory effect on the activity of 5'-nucleotidase, were found to be more effective in potentiating the Fe2+-mediated inactivation. Further, kinetic analyses indicate that Fe2+ and thiols inhibit the 5'-nucleotidase in a competitive or uncompetitive manner, respectively. These results suggest that ecto-5'-nucleotidase from brain membrane is one of proteins susceptible to thiols/Fe2+-catalyzed oxidation, and the oxidative inactivation may be related to the selective association of Fe2+ and thiols to the enzyme molecule.
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PMID:Oxidative inactivation of brain ecto-5'-nucleotidase by thiols/Fe2+ system. 1107 66

Cupric sulfate is an inorganic salt which is widely used in industry, agriculture, and veterinary medicine. Its applications include use as an algicide in potable waters and as a feed additive and therapeutic agent in swine, sheep, and cattle. Because copper salts are found in human water supplies, toxicity studies of cupric sulfate pentahydrate were conducted in male and female F344/N rats and B6C3F1 mice by the drinking water (2-week studies only) and dosed feed routes (2-week and 13-week studies). Animals were evaluated for hematology, clinical chemistry, urinalysis, reproductive toxicity, tissue metal accumulation, and histopathology. In the 2-week drinking water studies, groups of five rats and five mice per sex received cupric sulfate at concentrations of 300 to 30,000 ppm for 15 days. One female rat, one male mouse, and three female mice in the 3000 ppm groups and all rats and mice in the 10,000 and 30,000 ppm groups died before the end of the studies. The remaining mice and rats in the 3000 ppm groups gained little or lost weight. Water consumption in the three highest dose groups of both species was reduced by more than 65%. Clinical signs observed in these groups were typical of those seen in moribund animals and were attributed to dehydration. The only gross or microscopic change specifically related to cupric sulfate toxicity was an increase in the size and number of cytoplasmic protein droplets in the epithelium of the renal proximal convoluted tubule in male rats from the 300 and 1000-ppm groups. In the 2-week feed studies, groups of five rats and five mice per sex were fed diets containing 1000 to 16,000 ppm cupric sulfate. No chemical-related deaths occurred in any dose group. Compared to the controls, rats and mice in the two highest dose groups had reduced body weight gains which were attributed to decreased feed consumption. Hyperplasia with hyperkeratosis of the squamous epithelium on the limiting ridge of the forestomach was seen in rats and mice of each sex; this lesion was more severe in rats than in mice. Inflammation of the liver, periportal to midzonal in distribution, occurred in rats in the 8000 and 16,000 ppm groups. Depletion of hematopoietic cells was evident in rats of each sex in the bone marrow (8000 and 16,000 ppm) and spleen (16,000 ppm). Kidneys of male and female rats in the 4000, 8000, and 16,000 ppm groups had an increased number and size of protein droplets in the epithelia of the renal cortical tubules. In the 13-week feed studies, groups of 10 rats per sex received diets containing 500 to 8000 ppm cupric sulfate, and groups of 10 mice per sex received diets containing 1000 to 16,000 ppm cupric sulfate for 92 days; estimates of cupric sulfate consumption ranged from 32 to 551 mg/kg per day for rats and 173 to 4157 mg/kg per day for mice. There were no chemical-related deaths in rats or mice, and no clinical signs of cupric sulfate toxicity were recorded. Final mean body weights were lower than those of the controls for animals of both species receiving doses of 4000 ppm cupric sulfate and greater. In mice in the 13-week studies, there was a dose-related decrease in liver weights. Hematologic, clinical chemistry, and urinalysis evaluations of rats in the 13-week study revealed variable chemical-related changes that were, for the most part, restricted to the 4000 and 8000 ppm groups. Increases in serum alanine aminotransferase and sorbitol dehydrogenase activities in both sexes were indicative of hepatocellular damage, as were increases in 5'-nucleotidase and bile salts in males. Decreases in mean cell volume, hematocrit, and hemoglobin indicated the development of a microcytic anemia, while increases in reticulocyte numbers at the same time points suggested a compensatory response to the anemia by the bone marrow. Increases in urinary glucose and N-acetyl-beta-D-glucosaminidase (a lysosomal enzyme) and aspartate aminotransferase (alpha-cytosolic enzyme) were suggestive of renal tubule epithelial damage. Dose-related increases in copper occurred in all male rat tissues examined (lissues examined (liver, kidney, plasma, and testis). These increases were accompanied by increases in zinc in the liver and kidney. Plasma calcium was significantly reduced in the 4000 and 8000 ppm groups, and there was a trend toward reductions in calcium in the kidney and testis as well. In the 8000 ppm group, plasma magnesium was significantly increased relative to the controls. Rats in the three highest dose groups had hyperplasia and hyperkeratosis of the forestomach, inflammation of the liver, and increases in the number and size of protein droplets in the epithelial cytoplasm and the lumina of the proximal convoluted tubules. These effects were similar to those seen in the 2-week feed study, and the incidence and severity of these lesions were dose related. Many of the droplets in male rat kidneys were large and had irregular crystalline shapes. These droplets stained strongly positive for protein but were negative by iron, PAS, and acid-fast (lipofuscin) staining methods. α-2-Microglobulin was present in the droplets of male rats, but there was no dose- related, qualitative difference in the content of this protein. In the 4000 and 8000 ppm groups, copper was distributed in a periportal to midzonal pattern in the liver and was restricted to the cytoplasm of the proximal convoluted tubule epithelium in the kidney. Copper was present in some, but not all, of the protein droplets. Transmission electron microscopy of the livers of rats of each sex revealed increases in the number of secondary lysosomes in hepatocytes in the periportal area. In mice of each sex receiving 4000 ppm cupric sulfate and higher in the 13-week study, there was a dose-related increase in hyperplasia with hyperkeratosis of the squamous mucosa on the limiting ridge of the forestomach. Minimal positive staining for copper was present in the liver and was limited to high-dose (16,000 ppm) male and female mice. Cupric sulfate produced no adverse effects on any of the reproductive parameters measured in rats or mice of either sex. In summary, administration of cupric sulfate to rats in feed or drinking water resulted in significant gastric changes and hepatic and renal damage. The primary lesion in rats was an increase in the size and number of proteinaceous droplets in the epithelial cytoplasm and lumen of the proximal convoluted tubule. For rats in the 13-week study, the no-observed-adverse-effect level (NOAEL) for evidence of histologic injury to the kidney was 1000 ppm for males and 500 ppm for females, while the NOAEL for liver inflammation was 1000 ppm for males and 2000 ppm for females. Hyperplasia with hyperkeratosis of the epithelium on the limiting ridge separating the forestomach from the glandular stomach was also seen in rats of each sex, and the NOAEL for this change was 1000-ppm cupric sulfate in the feed. Additionally, clinical pathology alterations noted in the 13-week study, along with histologic changes in bone marrow noted in the 2-week feed study, were indicative of a microcytic anemia with a compensatory bone marrow response. Mice appeared to be much more resistant to the toxic effects of cupric sulfate than rats. The primary target tissue in mice was the epithelium of the limiting ridge of the forestomach. The NOAEL for the hyperplasia and hyperkeratosis seen at this site in mice was 2000-ppm cupric sulfate in the feed. Synonyms: Chalcanthite; Copper sulfate; cupric sulfate pentahydrate; bluestone; blue vitriol; Roman vitriol; Salzburg vitriol. (NOTE: These studies were supported in part by funds from the Comprehensive Environmental Response, Compensation, and Liability Act trust fund (Superfund) by an interagency agreement with the Agency for Toxic Substances and Disease Registry, U.S. Public Health Service.)
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PMID:NTP technical report on the toxicity studies of Cupric Sulfate (CAS No. 7758-99-8) Administered in Drinking Water and Feed to F344/N Rats and B6C3F1 Mice. 1220 95

A phosphodiesterase was purified from the venom of the snake Bothrops alternatus by a combination of gel filtration and ion exchange chromatographies. In SDS-PAGE, the enzyme gave a single band with a molecular mass of 105 kDa, which was unaltered in the presence of beta-mercaptoethanol, indicating that the protein contained no subunits. A single protein band was also observed in native PAGE. There were no contaminating 5'-nucleotidase, alkaline phosphatase and protease activities. The enzyme was recognized by commercial bothropic antiserum and gave a single band in immunoblotting. The enzyme had a pH optimum in the range of 7.5-9.5 and the optimum temperature was 60 degrees C, with activity being rapidly lost within 1 min at > or = 70 degrees C. The Km of the enzyme was 2.69 mM. PDE activity was potentiated by cobalt and, to a lesser extent, by calcium, whereas copper, manganese, zinc, EDTA, and beta-mercaptoethanol were inhibitory. These properties show that this enzyme is very similar to that isolated from other snake venoms.
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PMID:Purification and characterization of a phosphodiesterase from Bothrops alternatus snake venom. 1263 51

Male weaning rats were divided randomly into five groups. They were fed with diets containing zinc deficient(DZ), high zinc(HZ), normal zinc (NZ) and high zinc pair-fed with zinc deficient group(HZP) respectively. The rats in DZ and HZ groups were exchanged diets after 20 days. A part of rats in each group were killed at days 20, 50 and 70. The activities of alkaline phosphatase(ALP), 5'-nucleotidase(5'-NT) and copper-zinc-superoxidase dismutase(Cu-Zn-SOD), the zinc concentration in plasma and kidney were determined to assess the better indices for zinc nutrition. The results indicted that: The activities of ALP in DZ group at 20 d was significantly lower than that in the same group at the beginning, in the HZ group and in the HZP group, and increased significantly after the diet was changed to HZ diet after 30 days. The activities of 5'-NT in DZ group rats was decreasing with the extension of experimental period. These results indicated that the activities of ALP and 5'-NT were sensitive to zinc supplementation even though they were changed a little during zinc exhausted. The activity of ALP was decreasing with growing, and the activity of 5'-NT was increased with growing. Zinc concentration in plasma of DZ group was significantly lower than that of other groups which include DZ-HZ group at the 50th day, and it was also the lowest among groups at the end of experiment. Zinc concentration in the kidney of HZ-DZ group was significantly lower than that of HZ and DZ-HZ groups by the end of experiment. There were little changes of the activity of Cu-Zn SOD and the zinc content in kidney during the experiment period. These results indicated that the activities of both ALP and 5'-NT and plasma zinc were sensitive to zinc supplementacior and zinc deficiency.
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PMID:[Research on some enzyme activities in the assessment of zinc nutritional status of growing rats]. 1271 98

Zinc, copper and cadmium are important environmental contaminants and differences in purinergic and cholinergic systems of invertebrates have been described when compared to characteristics of these signaling systems in vertebrates. Here we evaluate the effect in vitro of these metals on the ATPase, 5'-nucleotidase and cholinesterase (ChE) activities in the digestive gland of Helix aspersa. Zinc (500 and 1000 microM) promoted a significant decrease in 5'-nucleotidase activity. However, it did not induce changes in ATP hydrolysis. Copper (25 and 50 microM), inhibited significantly ATPase activity, but did not alter 5'-nucleotidase when compared to control (no metal added). In relation to effects of cadmium, an inhibitory effect on ATP hydrolysis has been observed at concentrations of 100, 500 and 1000 microM and a similar decrease of AMP hydrolysis was observed at 500 and 1000 microM. However, there were no significant changes in ChE activity from homogenates of the digestive gland of H. aspersa for all metals tested. This study demonstrated that zinc, cadmium and copper affect ATPase and 5'-nucleotidase in digestive gland, but not ChE, suggesting that the purinergic system may be a target related to toxicity induced by these metals and a possible indicator of biological impact of exposure to these contaminants.
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PMID:In vitro exposure of heavy metals on nucleotidase and cholinesterase activities from the digestive gland of Helix aspersa. 1673 Feb 35


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