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)

Highly purified preparations of plasma membranes from control and ketoconazole-treated (1 microM, 120 h) epimastigotes of Trypanosoma cruzi have been obtained by cell disruption using abrasion with glass beads, differential centrifugation and isopycnic centrifugation in continuous, self-generating Percoll gradients. The purity of the preparation was ascertained by the specific activity 125I bound to the membranes obtained from enzymatically radiolabeled epimastigotes and by the alpha-methyl-mannoside sensitive binding of 125I-concanavalin A. The membranes form closed vesicles of 0.2-0.4 micron in diameter which display Mg2+ ATPase and acid phosphatase activities, but are devoid of 5'-nucleotidase and succinate-cytochrome c oxidoreductase; these vesicles can be strongly agglutinated by concanavalin A. The lipid order profiles of membranes from control and treated cells were compared with that present in egg phosphatidylcholine/ergosterol liposomes (84:16, mol/mol) by electron spin resonance spectroscopy of doxylstearic acid probes with the nitroxide group bound to carbon 5, 10, 12 and 16 of the stearic acid chain. Membranes from treated epimastigotes have a lipid order profile which resembles that of control plasma membranes near the polar surface (positions 5 and 10) but there is an abrupt decrease of order at position 12 and from there to the center of bilayer is highly disordered, even more than in pure lipid membranes. Consistent with these results, the leakage of L-[14C]glucose from membrane vesicles of ketoconazole-treated cells is much faster than that observed in vesicles obtained from control cells. These results indicate a strong alteration of the plasma membrane physical and biological properties due to the incubation of the parasite with the drug; this alteration is consistent with the accumulation of methylated precursors of ergosterol, which affects both lipid-lipid and lipid-protein interactions in the membrane.
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PMID:Alteration of lipid order profile and permeability of plasma membranes from Trypanosoma cruzi epimastigotes grown in the presence of ketoconazole. 284 68

The activity of key enzymes of adenosine metabolism was studied in the developing fetal guinea pig brain. The activities of 5'-nucleotidase and adenosine deaminase were determined in the brains of fetal guinea pigs at 30, 35, 40, 45, 50, 55, and 60 days of gestation. The level of 5'-nucleotidase activity was extremely low at 30 and 35 days of gestation but increased rapidly during the 40 to 60 day period. The enzyme activity increased in the presence of Mg2+ with the Mg2+ - dependent activation increasing with the age of gestation. This Mg2+ - dependent activity was primarily associated with the membrane fraction. Prenatal hypoxia significantly increased the fetal brain M2+ - independent 5'-nucleotidase activity at 45 days of gestational age and beyond. Prior to this age, no effect was evident. Furthermore, following hypoxia, the Mg2+ - dependent activation of 5'-nucleotidase activity was lost. The activity of adenosine deaminase was present at 30 days of gestation and, unlike 5'-nucleotidase, it remained at the same level until 60 days. The results indicate that the term fetal guinea pig brain has the enzymatic mechanisms of adenosine metabolism and thus the potential for adenosine-mediated regulation of cerebrovasculature during hypoxia.
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PMID:5'-Nucleotidase and adenosine deaminase in developing fetal guinea pig brain and the effect of maternal hypoxia. 285 7

Because adenosine plays a role in the regulation of glomerular filtration rate and of the release of renin, we examined the possibility of a local source for this mediator. We found that rat cultured glomerular mesangial cells converted 5'-AMP into adenosine. The properties of the enzyme involved in the reaction were those of an ecto-5' nucleotidase: (1) the products of the reaction were generated in the extracellular fluid although no 5'-nucleotidase was released by the cells into the medium; (2) identical activities were found for cultured cells in situ and sonicated cells; (3) the diazonium salt of sulfanilic acid which is a nonpenetrating reagent inhibited up to 75% of the enzyme activity. Ecto-5'-nucleotidase activity of intact cells obeyed Michaelis-Menten kinetics. Apparent Km for 5'-AMP was 0.32 mM. 5'-UMP was a strictly competitive inhibitor. ADP exerted a very powerful inhibitory effect and behaved also as a competitive inhibitor. ATP was inhibitory both by increasing Km and by decreasing Vmax. Ecto-5'-nucleotidase was active in the absence of divalent cations. However, Mg2+, Ca2+, Co2+ and Mn2+ were stimulatory. Zn2+ and Cu2+ suppressed the activity. Concanavalin A, a plant lectin, was markedly inhibitory, suggesting that a glycoprotein moiety was necessary to express enzyme activity. Ecto-5'-nucleotidase activity was not modified during phagocytosis of serum-treated zymosan by mesangial cells. Rat cultured glomerular epithelial cells exhibited a 5'-nucleotidase activity which was 4 times lower than that of the mesangial cells in primary culture.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Ecto-5'-nucleotidase of cultured rat mesangial cells. 285 4

Male Wistar rats were given drinking water ad libitum with 0.075% thioacetamide (TAA) for 4 weeks. TAA treatment did not affect serum aminotransferase activities and total bilirubin content. The activities of 5'-nucleotidase, K+, Na+- and Mg2+-adenosine triphosphatases in liver plasma membrane preparations were strongly depressed, while that of gamma-glutamyl transferase was considerably increased. A decline in liver microsomal cytochrome P-450 and cytochrome b5 concentrations was also recorded. In contrast, the content of reduced glutathione in liver homogenate supernatant (9000 g) increased about 2-fold. As plasma membrane associated enzymes seem to be exclusively affected, the liver plasma membrane could be involved in the pathogenesis of the TAA-induced precirrhotic liver changes.
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PMID:Biochemical changes in the rat after chronic thioacetamide intoxication. 289 87

We have characterized ATP-dependent Ca2+ transport into highly purified plasma membrane fraction isolated from guinea pig ileum smooth muscle. The membrane fraction contained inside-out sealed vesicles and was enriched 30-40-fold in 5'-nucleotidase and phosphodiesterase I activity as compared to post nuclear supernatant. Plasma membrane vesicles showed high rate (76 nmol/mg/min) and high capacity for ATP dependent Ca2+ transport which was inhibited by addition of Ca2+ ionophore A23187. The inhibitors of mitochondrial Ca2+ transport, i.e., sodium azide, oligomycin and ruthenium red did not inhibit ATP-dependent Ca2+ uptake into plasma membrane vesicles. The energy dependent Ca2+ uptake into plasma membranes showed very high specificity for ATP as energy source and other nucleotide triphosphates were ineffective in supporting Ca2+ transport. Phosphate was significantly better as Ca2+ trapping anion to potentiate ATP-dependent Ca2+ uptake into plasma membrane fraction as compared to oxalate. Orthovanadate, an inhibitor of cell membrane (Ca2+-Mg2+)-ATPase activity, completely inhibited ATP-dependent Ca2+ transport and the Ki was approximately 0.6 microM. ATP-dependent Ca2+ transport and formation of alkali labile phosphorylated intermediate of (Ca2+-Mg2+)-ATPase increased with increasing concentrations of free Ca2+ in the incubation mixture and the Km value for Ca2+ was approximately 0.6-0.7 microM for both the reactions.
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PMID:Characterization of Ca2+ uptake in plasma membrane vesicles isolated from guinea pig ileum smooth muscle. 295 Oct 13

In a subcellular plasma membrane enriched fraction of bovine corneal epithelium, Ca2+ stimulated Mg2+ dependent ATPase activity was characterized. This membrane fraction was more than 5-fold and 4-fold enriched with 5'-nucleotidase and alkaline phosphatase activities, respectively, relative to the 100,000 X g pellet. With 250 microM ATP, maximum stimulation of a high affinity form of Ca2+ stimulated Mg2+ dependent ATPase activity was obtained with 1.7 microM free Ca2+. This activation required no exogenously added Mg2+ and was unaffected by either 0.1 mM ouabain, 3 microM ruthenium red, 20 mM sodium azide or 0.2 microgram/ml oligomycin. Exogenous calmodulin (6 microM) elicited a 53% increase in this activity which was completely inhibited by 300 microM trifluoperazine (TFP). These effects of calmodulin and TFP are consistent with the notion of a plasma membrane origin for this activity and also suggest that this activity could be a basis for the regulation of intracellular Ca2+ activity in the submicromolar range.
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PMID:Ca-stimulated Mg dependent ATPase activity in a plasma membrane enriched fraction of bovine corneal epithelium. 295 65

The following enzymes have been studied (subcellular fractions are shown between parentheses): NAG and beta-glucuronidase (lysosomes); SDH (mitochondrial); glucose-6-phosphatase (endoplasmic reticulum); 5'-nucleotidase and (Na+, K+)Mg2+ ATPase (plasma membranes). Alterations on their activities were observed after subcutaneous injection of sex hormones, compared with controls. NAG activity from liver was always significantly decreased in lysosomal and microsomal fractions after the hormonal treatment. In the same conditions, NAG from brain was always increased. beta-Glucuronidase behaves like NAG in brain; in liver it was not modified by testosterone and it was slightly increased in lysosomal fraction after oestradiol treatment. SDH activity was not modified in mitochondrial fractions from liver, but this activity was always significantly increased in brain. Glucose-6-phosphatase activity was always significantly decreased in microsomal fractions from liver. It was increased in brain after oestradiol and testosterone injection, but medroxyprogesterone treatment caused a decreased activity. 5'-Nucleotidase and (Na+, K+)Mg2+ ATPase from brain were significantly increased in microsomal fractions by oestradiol and testosterone. Medroxyprogesterone, however, caused an increase in ATPase, but did not affect 5'-nucleotidase. Both activities in liver were decreased by oestradiol and increased by testosterone, but medroxyprogesterone caused (Na+, K+)Mg2+ ATPase to rise and 5'-nucleotidase to fall.
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PMID:Effects of oestradiol, testosterone and medroxyprogesterone on subcellular fraction marker enzyme activities from rat liver and brain. 298 29

5'-Nucleotidase (EC 3.1.3.5) has been solubilized and purified 1200-fold from guinea-pig skeletal muscle, to a specific activity of 40 U/mg protein. The purified enzyme yields a single protein band on polyacrylamide gel electrophoresis in the presence of sodium dodecyl sulfate. Guinea-pig skeletal muscle 5'-nucleotidase is extremely sensitive to inhibition by nucleoside di- and triphosphates. The inhibition is of the competitive type, and can be reversed only by strong excess of Mg2+. Nucleoside diphosphates are more powerful inhibitors than nucleoside triphosphates. The Ki values for ADP and ATP are 0.036 and 0.28 microM, respectively. The purified enzyme does not require exogenous cations for maximal activity and is inhibited by EDTA. This inhibition is reversed by divalent cations. This indicates that the enzyme contains a tightly bound metal cation.
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PMID:Isolation and kinetic properties of 5'-nucleotidase from guinea-pig skeletal muscle. 298 11

The effect of subcutaneous injection of hydrocortisone and corticosterone on the activity values of some subcellular fractions marker enzymes from rat liver and brain was investigated and compared with controls (without treatment with hormones). The following enzymes were studied (subcellular fraction are shown between parentheses): N-acetyl-beta-D-glucosaminidase and beta-glucuronidase (lysosomes); succinate dehydrogenase = SDH (mitochondria); glucose-6-phosphatase (endoplasmic reticulum); 5'-nucleotidase and Na+-K+-Mg2+ ATPase (plasma membrane). The specific activity of lysosomal enzymes from liver showed no change when rats were injected either with hydrocortisone or corticosterone. The same enzymes from brain showed significant increases in their activities with both hydrocortisone or corticosterone except beta-glucuronidase; this enzyme gave activity values remaining between the control levels, after treatment with corticosterone. The activity of mitochondrial SDH was increased after corticosterone injection either in liver or brain. After hydrocortisone injection, its activity rises significantly in brain (72%), but it falls in liver compared to the control values. Glucose-6-phosphatase behaves similarly in brain or liver fractions; its activity increases always after corticosterone treatment and decreases by hydrocortisone. The plasma membrane marker enzymes did not change practically in brain fractions, excepted Na+-K+-Mg2+ ATPase which tends to rise its activity after hydrocortisone injection. In liver fractions, both 5'-nucleotidase and Na+-K+-Mg2+ ATPase activities increase either by corticosterone or hydrocortisone treatment, except 5'-nucleotidase which specific activity decreases in liver after hydrocortisone treatment.
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PMID:Alterations in the activities of subcellular fractions marker enzymes in rat liver and brain by hydrocortisone and corticosterone treatment. 298 17

The plasma membranes isolated from rat liver bound 125I-labelled ([125I]) synthetic [Asu1,7]eel calcitonin (CT), with increasing concentrations of [125I]CT. This specific binding was completely saturated at a concentration of 0.5 nM CT. A high affinity Ca2+-stimulated, Mg2+-dependent ATPase [(Ca2+-Mg2+)-ATPase] activity in the plasma membranes was significantly decreased by the presence of a very low concentration of CT (7.4 pM), although the hormone did not affect the activity of the plasma membrane 5'-nucleotidase. The concentration of CT needed for maximal inhibition of (Ca2+-Mg2+)-ATPase in the plasma membranes was less than 0.74 nM. The plasma membranes washed with 10(-3)% digitonin did not show an inhibitory effect of CT on (Ca2+-Mg2+)-ATPase activity, while the reagent did not have a significant effect on the enzyme. These results suggest that the inhibition of (Ca2+-Mg2+)-ATPase activity may be part of the mechanism by which CT elevates cytosolic Ca2+ in liver cells.
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PMID:Regulation of (Ca2+-Mg2+)-ATPase activity by calcitonin binding to rat liver plasma membranes. 299 35


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