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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)

Vibrio parahaemolyticus utilized ATP, ADP or AMP as the sole source of carbon. About three times higher activity of membrane-bound 5'-nucleotidase was observed in cells grown in the presence of these nucleotides than in their absence: and therefore the enzyme seems to be inducible. Since the 5'-nucleotidase activity could be measured with whole cells, the active site of this enzyme appears to be outwardly oriented. Both Mg2+ and Cl- were required for activity. Among the divalent cations tested, Mn2+ and Co2+ could replace Mg2+ to some extent, whereas Zn2+ strongly inhibited activity. Among the anions tested, Br-, I- and NO3- could replace Cl-, but SO4(2-) and CH3COO- could not. When cells were grown with ATP, Cl- was indispensable and Zn2+ strongly inhibited growth. Therefore, it is concluded that extracellular ATP and other 5'-nucleotides are cleaved by the membrane-bound 5'-nucleotidase outside the cells and that the adenosine produced is then utilized.
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PMID:Properties of the membrane-bound 5'-nucleotidase and utilization of extracellular ATP in Vibrio parahaemolyticus. 283 22

An enzyme with FAD pyrophosphatase activity was extracted from human placental syncytiotrophoblast microvilli and purified to near-homogeneity. The enzyme has been identified as 5'-nucleotidase by several criteria. Throughout purification, parallel increases in the specific activities of FAD pyrophosphatase and AMP phosphatase were observed. The enzyme was a glycoprotein with a subunit molecular weight of 74,000. EDTA treatment resulted in a marked decline in both activities, and restoration of FAD pyrophosphatase activity but not 5'-nucleotidase activity was accomplished by the addition of Co2+ or, to a lesser extent, Mn2+. The substrate specificity of the 5'-nucleotidase activity that we observed agreed closely with the results of others. The pyrophosphatase activity was relatively specific for FAD. ADP, ATP, NAD(H), and FMN were not hydrolyzed, and ADP strongly inhibited both activities. For FAD pyrophosphatase activity, a Km of 1.2 x 10(-5) M and a Vmax of 1.1 mumol/min/mg protein were determined in assays performed in the presence of Co2+. In the absence of added Co2+, the Vmax declined but the Km was unchanged. For 5'-nucleotidase (AMP as substrate) the Km was 4.1 x 10(-5) M and the Vmax 109 mumol/min/mg protein. Hydrolysis of FMN to riboflavin was observed in partially purified detergent extracts of microvilli that contained alkaline phosphatase activity and lacked FAD pyrophosphatase and 5'-nucleotidase activity. The presence of both FAD pyrophosphatase and FMN phosphatase activities in syncytiotrophoblast microvilli supports the view that the placental uptake of vitamin B2 involves the hydrolysis of FAD and FMN to riboflavin which is then absorbed, a sequence postulated for intestinal absorption and liver uptake.
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PMID:5'-Nucleotidase of human placental trophoblastic microvilli possesses cobalt-stimulated FAD pyrophosphatase activity. 284 89

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

Activity of cobalt activated acylase, gamma-glutamyltransferase, leucylaminopeptidase and alanylaminopeptidase in serum and liver of mice with transplantable leukemias (L1210, L1210/ara-C, L1210/CH3-G, AKSL-4, plasmacytoma ADJ-PC-5) were determined. Adenosinotriphosphatase, 5'-nucleotidase and alkaline phosphatase were histochemically localized in lymphatic nodes and spleen. Among the investigated enzymes the rise in serum activity of cobalt activated acylase and gamma-glutamyltransferase was demonstrated. A substantial increase of leucylaminopeptidase and alanylaminopeptidase was shown in the liver. A decrease in the histochemical reactions of all the studied enzymes was observed.
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PMID:Enzyme activity in mice with transplantable leukemia. 287 46

The fes mutation in Escherichia coli K12, which inactivates enterochelin esterase, allows the cell to accumulate ferric enterochelin. The ferric complex of enterochelin was released in significant quantities from a fes mutant after osmotic shock. Analysis of the effects of the individual stages of the shock procedure in wild-type cells showed that prior exposure of cells to sucrose and EDTA was not required, careful dilution of cells into a hypo-osmolar medium being sufficient to induce efflux of Fe3+. Prior treatment with EDTA or exposure to shearing forces served either to enhance efflux or to induce efflux in isotonic media. Neither vitamin B12 nor 5'-nucleotidase was released from the periplasm by these procedures. The release observed under mild conditions was stimulated specifically by Co2+, did not occur at 0 degree C, and was inhibited by 2,4-dinitrophenol at 37 degrees C. From these observations, it was concluded that the efflux of Fe3+ represents a physiological response of the cell to exposure to a hypo-osmolar medium. Such changes may enhance survival following physicochemical stressing of the bacterial outer membrane.
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PMID:Effect of osmotic shock and shearing forces on ferric enterochelin transport in Escherichia coli K12. 295

The effects of zinc on the enzymes of femoral tissue were investigated in weanling rats that had been given zinc sulfate (1.0 mg Zn2+/100 g body wt) p.o. for 3 days. Administration of zinc caused a marked elevation of alkaline phosphatase and acid phosphatase activities, whereas it did not cause significant changes in succinate dehydrogenase, 5'-nucleotidase, ATPase, pyrophosphatase and beta-N-acetylglucosaminidase activities. The effect of zinc was greater on alkaline phosphatase of the femoral diaphysis. Zinc content of the femoral diaphysis was raised significantly by administration of zinc. The addition of zinc in concentrations of 10(-2)-10(2) microM did not produce a significant increase in alkaline phosphatase activity in the femoral diaphysis, indicating that zinc could not activate the enzyme. Administration of cycloheximide or actinomycin D completely inhibited the increase in alkaline phosphatase activity produced by administration of zinc. DNA content of the femoral diaphysis, but not epiphysis, was increased markedly by administration of zinc. The increases in both alkaline phosphatase activity and DNA content of the femoral diaphysis were not caused by administration of copper, manganese, cobalt, nickel and chromium(III). The present investigation suggests that zinc may induce the increase in alkaline phosphatase related to DNA synthesis and, as a result, stimulate bone growth.
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PMID:Action of zinc on bone metabolism in rats. Increases in alkaline phosphatase activity and DNA content. 395 86

All members of the Enterobacteriaceae possess distinct 5'-nucleotidases and cyclic phosphodiesterases (3'-nucleotidases) that can be differentiated from the acid and alkaline phosphatases and the acid sugar hydrolases. The nucleotidases and cyclic phosphodiesterases of the various Enterobacteriaceae are remarkably similar in properties. All of the 5'-nucleotidases hydrolyze 5'-nucleotides, adenosine triphosphate, and uridine diphosphoglucose. Their pH optimum is from 5.7 to 6.1. The cyclic phosphodiesterases hydrolyze 3'-nucleotides, cyclic phosphonucleotides, bis-(p-nitrophenyl)phosphate, and p-nitrophenylphosphate. Their pH optimum is from 7.2 to 7.8. For both enzymes, cobalt showed optimal metal stimulation. An intracellular protein inhibitor for the 5'-nucleotidase is present in all of the Enterobacteriaceae. No inhibitor of cyclic phosphodiesterase activity exists, although hydrolysis of both cyclic phosphonucleotides and 3'-nucleotides is inhibited by ribonucleic acid. Neither of the enzymes is subject to control by phosphate level or by catabolite repression. Of the other bacteria studied, only Haemophilus and Bacillus subtilis contained significant 3'- or 5'-nucleotidase activity.
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PMID:The 5'-nucleotidases and cyclic phosphodiesterases (3'-nucleotidases) of the Enterobacteriaceae. 496 71

Human lymphocytes were isolated from defibrinated blood by Ficoll-Hypaque centrifugation with erythrocyte hypotonic lysis. Homogenates of mixed lymphocytes were subjected to analytical subcellular fractionation by sucrose gradient centrifugation in a Beaufay automatic zonal rotor. The principal organelles were characterized by their marker enzymes: cytosol (lactate dehydrogenase), plasma membrane (5'-nucleotidase), endoplasmic reticulum (neutral alpha-glucosidase), mitochondria (malate dehydrogenase), lysosomes (N-acetyl-beta-glucosaminidase), peroxisomes (catalase). gamma-Glutamyl transferase was exclusively localized to the plasma membrane. Leucine amino-peptidase, especially when assayed in the presence of Co2+, was also partially localized to the plasma membrane. Experiments with diazotized sulphanilic acid, a non-permeant enzyme inhibitor, showed that these plasma membrane enzymes are present on the cell surface. No detectable alkaline phosphatase was found in the lymphocytes. Acid phosphatase and beta-glucuronidase were localized to lysosomes and there was some evidence for lysosomal heterogeneity. Leucine amino peptidase, optimal at pH 8.0, showed a partial localization to intracellular vesicles, possibly lysosomes, especially when assayed in the presence of EDTA. These studies provide a technique for determining the intracellular distribution of hitherto unassigned lymphocyte constituents and serve as a basis for investigating the cell pathology of lymphocytic disorders.
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PMID:Enzyme analysis and subcellular fractionation of human peripheral blood lymphocytes with special reference to the localization of putative plasma membrane enzymes. 614 55

Rat brain myelin showed substantial activity of 5'-nucleotidase. The specific activity in myelin was enriched two- to threefold over that in rat brain homogenates, and the total activity in myelin accounted for approximately 24% of the activity in the homogenates. The 5'-nucleotidase in the homogenates and in isolated myelin had optimum activity at pH 7.5--9.0, was stimulated by Mg2+ and Mn2+, and was inhibited by Co2+, Zn2+, EDTA, and EGTA. 5'-AMP, 5'-UMP, and 5'-CMP were the preferred substrates, and 5'-GMP was hydrolyzed at approximately one-half the rate of the other mononucleotides. The very low rates of cleavage of beta-glycerophosphate and 2'-AMP ruled out any significant contribution of nonspecific phosphatase to the observed 5'-nucleotidase activity in myelin. The 5'-nucleotidase was inhibited by concanavalin A and was protected by alpha-methyl-D-mannoside against inhibited by that lectin, suggesting that this enzyme in the CNS is a glycoprotein. It is concluded from these data, and from histochemical observations made in other laboratories, that the myelin sheath is one major locus of 5'-nucleotidase in the rat brain.
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PMID:5'-nucleotidase in rat brain myelin. 625 85

A surface membrane fraction isolated from Leishmania donovani promastigotes contained distinct 5'- and 3'-nucleotidase activities. These were distinguished from each other, and from a previously described surface membrane nonspecific acid phosphomonoesterase, on the basis of several properties. The 5'- and 3'-nucleotidases had p' optima of 6.5 and 8.5, respectively. In contrast to the 3'-nucleotidase, the 5'-nucleotidase was inhibited by both ammonium molybdate and fluoride ions; the latter inducing a biphasic response. Neither divalent cations nor chelators affected the 5'-enzyme activity whereas the 3'-enzyme was inactivated by EDTA. This inactivation was fully reversed following removal of the chelator, either by resuspension of the membranes in EDTA free medium or by addition of certain divalent cations in excess; Co2+ being the most effective. The 5'-nucleotidase had activity with both ribo- and deoxyribonucleotide substrates, whereas the 3'-nucleotidase did not hydrolyse deoxyribonucleotides.
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PMID:Evidence for distinct 5'- and 3'-nucleotidase activities in the surface membrane fraction of Leishmania donovani promastigotes. 630 42


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