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)

The orientation of the enzyme Mg(2+)-ATPase (EC 3.6.1.3) in the transverse tubule (TT) membranes of skeletal muscle was investigated using highly purified chicken and rabbit TT vesicles. The percentage of sealed vesicles present in these preparations averaged 88 and 78%, respectively, as calculated from the detergent-induced increase in ouabain-sensitive (Na+, K+)-ATPase activity, ATP-dependent ouabain binding, and lactate dehydrogenase activity (sarcoplasmic enzyme trapped in the TT vesicles). Sidedness of the sealed vesicles, estimated from latency of 5'-nucleotidase, acetylcholinesterase, and adenylate cyclase, was predominantly right-side out (69-76%, chicken TT and 62-70%, rabbit TT). In both chicken and rabbit native vesicles, high Mg(2+)-ATPase activity was detected by addition of ATP to the extravesicular medium; this activity was increased 14-12% by alamethicin pointing to the external localization of the active site. Furthermore, the enzymatic activity resulted partially inhibited by treatment of the chicken TT vesicles with proteinase K or p-hydroxymercuribenzoate. Concanavalin A stimulated 4-fold the chicken TT Mg(2+)-ATPase activity, an effect not potentiated by detergent permeabilization of the intact vesicles, indicating that lectin-binding sites were also solvent accessible. This stimulatory effect was not observed in native or permeabilized rabbit TT vesicles. From these results we conclude that the TT Mg(2+)-ATPase is an ectoenzyme with its nucleotide-hydrolyzing site and glycosylated regions facing the extracellular space. Inhibitors of ion-motive ATPases did not modify the enzyme activity, suggesting a different physiological role for the TT Mg(2+)-ATPase which may be involved in the regulation of muscle fiber functions affected by extracellular ATP levels.
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PMID:Transverse tubule Mg(2+)-ATPase of skeletal muscle. Evidence for extracellular orientation of the chicken and rabbit enzymes. 166 Apr 76

Cytochemical techniques associated with transmission electron microscopy were used for the localization in Tritrichomonas foetus of enzymes used as markers of different cell structures. Reaction product indicating the presence of Mg(2+)-adenosine triphosphatase (Mg(2+)-ATPase) and 5'-nucleotidase was observed in the plasma membrane. Glucose-6-phosphatase was seen in association with the endoplasmic reticulum, revealing its organization as parallel cisternae. Thiamino-pyrophosphatase was located in the cis-most region of the Golgi complex. Acid phosphatase was found within lysosomes as well as in several cisternae of the Golgi complex, in contrast to previous observations in mammalian cells. These observations provide support for the use of enzyme markers in future studies on cell fractionation of T. foetus.
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PMID:Cytochemical localization of enzyme markers in Tritrichomonas foetus. 166 35

Bile secretory failure (cholestasis) may result from several possible mechanisms involved in bile secretion. We have examined the possibility that abnormalities in enzyme content, composition, and turnover of liver plasma membrane constituents are altered in cholestasis. Severe and mild cholestasis were produced by 5 days of bile duct ligation and ethinyl estradiol administration, respectively. Bile duct ligation but not ethinyl estradiol treatments was associated with elevations of the serum bilirubin level and 5'-nucleotidase activity. However, basal bile flow and bilirubin transport maximum (T(m)) were significantly reduced after ethinyl estradiol treatment. Liver plasma membrane fractions rich in canalicular membranes were prepared from groups of rats in each of three categories; normal, after bile duct ligation, or ethinyl estradiol administration, and their respective controls. Electron microscopy and enzyme marker studies demonstrated plasma membrane fractions free of significant contamination. Plasma membrane fractions prepared from mild as well as severe cholestasis had increased alkaline phosphatase activity, and reduced 5'-nucleotidase and Mg(2+)-ATPase activities. Co(2+)-CMPase activity was unchanged. Kinetic analysis of 5'-nucleotidase and Mg(2+)-ATPase activities in plasma membrane fractions demonstrated reduced V(maz) (but unaltered K(m)). Reducted V(maz) was unrelated to addition in vitro of di-or trihydroxy bile salts or ethinyl estradiol and, therefore, suggests that reduced activities in cholestasis are due to decreased enzyme content. Cholestasis was not associated with changes in the synthesis or degradation rate of pulse-labeled plasma membrane proteins or alterations in the major protein bands separated on sodium dodecyl sulfate (SDS)-polyacrylamide gel electrophoresis. Plasma membrane cholesterol, phospholipid, and neutral sugar content was unaltered, but sialic acid content was significantly increased in both forms of cholestasis. Alterations in specific canalicular enzymes in two forms of cholestasis suggest that these changes may be involved in the pathogenesis of bile secretory failure, or may result from cholestasis.
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PMID:Alteration of bile canalicular enzymes in cholestasis. A possible cause of bile secretory failure. 426 20

On exposing promastigotes of L. donovani (Dd-8) to 34 degrees C for 30 hr, the flagella were shed, and size was decreased with 10% viability loss. The in vitro and in vivo infectivity of two forms was more or less similar. The 45Ca2+ uptake by the transformed cells was increased as compared to normal cells. Activity of 5'-nucleotidase was increased while activity of Mg(2+)-ATPase remained same. Parasite antioxidant enzymes were also significantly altered by heat shock. There was significant increase in superoxide dismutase, glutathione reductase and glutathione peroxidase. It was accompanied by decrease in ratio of reduced glutathione to oxidized glutathione.
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PMID:Biochemical changes in heat stressed promastigotes of Leishmania donovani. 760 93

The purpose of this study was to determine whether myocardial adenosine triphosphatase (ATPase) activities were reduced in pigs with naturally occurring hypertrophic cardiomyopathy (HCM). The selection of hearts for the HCM and the normal control groups depended on histological examination. Specific ATPase activity and 5'-nucleotidase activity were measured in left ventricular myocardium obtained from HCM (n = 7) and normal control (n = 7) animals. The histological features of HCM included marked disorientation of muscle cells, thickening of the intramural coronary arterial wall with a narrowed lumen, endocardial fibrosis and myocardial fibrosis. The HCM group showed significant increases in both heart weight (32%) and heart weight to body weight ratio (46%). The total ATPase activity in crude homogenates from the HCM group was significantly decreased by 16%. Azide-sensitive ATPase (mitochondrial ATPase) activity, ouabain-sensitive ATPase (Na+, K+-ATPase) activity, basal Mg(2+)-ATPase activity and Ca(2+)-ATPase activity were all significantly decreased by 18%, 30%, 20% and 50%, respectively. In contrast, no significant decrease was found in the mean values for 5'-nucleotidase activity. These results suggest that myocardial ATPase activities are suppressed in pigs with naturally occurring HCM.
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PMID:Altered adenosine triphosphatase activities in pigs with naturally occurring hypertrophic cardiomyopathy. 764 94

ATPase activities in CNS membranes were studied after administration of desipramine (DMI), a noradrenaline (NA) uptake inhibitor. In a previous paper we reported that Na+,K(+)-ATPase activity significantly increased 3 h after DMI administration (10 mg/kg) in hypothalamus and mesencephalus but not in cerebral cortex and pons-medulla oblongata membranes (Viola et al., Cell. molec. Neurobiol. 1989, 9, 263-271). Here it was observed that Na+,K(+)-ATPase increase induced by acute DMI disappeared at 24 h in hypothalamus but remained during 21 days in mesencephalus. Na+,K(+)-ATPase increase by acute DMI was inhibited when endogenous NA was depleted by the noradrenergic neurotoxin DSP-4 or the NA synthesis inhibitor alpha-methyl-p-tyrosine. On the whole, Mg(2+)-ATPase activity was not modified by treatment. 5'-nucleotidase, another membrane-bound enzyme, was unchanged by acute DMI. The addition of DMI in vitro (50 ng/mg tissue) during Na+,K(+)-ATPase assay failed to affect ATPase activities. Acute DMI effects on Na+,K(+)-ATPase are thus attributable to noradrenergic neurotransmission rather than to non-specific drug-CNS membrane interaction. Furthermore, DMI produces differential effects on membrane Na+,K(+)-ATPase, depending on treatment conditions and CNS area studied.
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PMID:Na+,K(+)-ATPase activity in CNS and noradrenergic neurotransmission: time course of differential desipramine (DMI) effects. 813 Jul 40

A preliminary investigation of enzymes functioning at the cell surface indicates that when Walker 256 carcinoma cells growing ascitically are induced to grow as a solid tumour there is a marked increase in the activities of Na+, K(+)-ATPase, Mg(2+)-ATPase, 5'-nucleotidase, alkaline phosphatase and phosphodiesterase I; 5'-nucleotidase and alkaline phosphatase being particularly affected. These enzyme changes occur in the absence of any major alteration in the protein composition of the plasma membrane.
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PMID:Protein and enzyme content of plasma membranes derived from Walker 256 carcinoma cells grown as ascitic or solid tumours. 838 3

Ochratoxin A is a mycotoxin produced by Aspergillus ochraceus and is a natural contaminant of moldly food. Ochratoxin A has a number of toxic effects, some of which may be related to the changes in the cell membrane. We measured the activities of 5 pancreatic, membrane bound enzymes in female Fisher rats that were given low oral doses of ochratoxin A (120 micrograms/kg body weight per day) during 20-35 days. The amount of toxin corresponds to 1.5 mg/kg in the feed, daily. These doses are in the range of natural contamination found in feed. The enzymes studied were alanine aminopeptidase, alkaline phosphatase, ecto-Ca2+/Mg(2+)-ATPase, gamma-glutamyl transferase and ecto-5'-nucleotidase. Treatment lasting 20 days caused a strong decrease in the activity of alanine aminopeptidase, Ca2+/Mg(2+)-ATPase and alkaline phosphatase to 0.76 +/- 0.04, 0.53 +/- 0.03 and 0.30 +/- 0.02 of the control values, respectively (p < 0.05). No significant changes in the activity of gamma-glutamyl transferase and 5'-nucleotidase were observed. However, activity of alanine aminopeptidase returned to normal values after 35 days of treatment, suggesting an adaptation of the organism, or a substitution of a released enzyme. Activities of alkaline phosphatase and Ca2+/Mg(2+)-ATPase remained significantly reduced to 0.42 +/- 0.03 and 0.52 +/- 0.04, respectively (p < 0.01). We conclude that treatment of rats with low doses of ochratoxin A resulted in reduction of the activities of the membrane bound enzymes, most probably by inducing their release, as a result of the impairment of the functional integrity of cell membranes.
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PMID:Ochratoxin A impairs activity of the membrane bound enzymes in rat pancreas. 860 90

The histochemical localisation of two ecto-enzymes, 5'-nucleotidase (5'-NT) and Mg(2+)-ATPase, was investigated in hyperplastic and recurrent tonsillitis. Detection of enzymes was performed on frozen sections using the classical lead nitrate method. Activity of 5'-NT was demonstrated particularly in the cells of lymphoid follicles and in the basal layer of the surface tonsillar epithelium. There was no difference in localisation of 5'-NT between hyperplastic and recurrent tonsillitis, whereas a stronger reaction in follicular mantle zones was observed in recurrent tonsillitis compared to hyperplastic tonsillitis. Mg(2+)-ATPase activity was mainly associated with the cells lining the tonsillar crypt, with the interfollicular areas and blood vessels. In recurrent tonsillitis only half of the studied follicular germinal centres expressed Mg(2+)-ATPase activity, compared to hyperplastic tonsillitis. The similar localisation of 5'-NT and ecto-ATPase in both types of chronic tonsillitis suggests that in inflamed tonsils expression of investigated enzymes probably does not depend on the type of chronic tonsillitis.
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PMID:Localisation of ecto-5'-nucleotidase and divalent cation-activated ecto-ATPase in chronic tonsillitis. 957 64

The activities of two ectoenzymes,Mg(2+)-ATPase (ATPase) and 5'-nucleotidase (5'-NT) from tonsillar mononuclear cells (TMC) and peripheral blood mononuclear cells (PBMC) were investigated in idiopathic tonsillar hyperplasia and recurrent tonsillitis. The ATPase activity of TMC was significantly higher in recurrent tonsillitis than in idiopathic tonsillar hyperplasia, whereas no difference was demonstrated in ATPase activity of PBMC. The activity of 5'-NT was similar in both investigated groups. However, ATPase and 5'-NT activities were significantly higher in TMC compared to PBMC. Such results suggest a possible role of ATPase in the activation of TMC during the course of chronic tonsillitis and indicate a difference in the function of TMC and PBMC.
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PMID:Divalent cation-activated-ATPase and ecto 5'-nucleotidase activities in chronic tonsillitis. 989 64


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