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)

Synaptosomes were prepared from rat cortex by subjecting a washed crude mitochondrial pellet to centrifugation first on discontinuous Ficoll-isotonic sucrose gradients and then on discontinuous sucrose gradients. The synaptosome fraction, collected from the 7.5-14% Ficoll band (II), was further separated into two additional fractions, designated IIA and IIB, which bank at the 0.32-1.05 M and at the 1.05-1.6 M sucrose interfaces, respectively. Electron microscopic analysis showed that fraction IIB contained synaptosomes and extra terminal mitochondria and was essentially free of membrane fragments. Further characterization showed that IIB contained 69% of the protein and 83% of the lactic dehydrogenase activity of fraction II and had a specific activity of a 2',3'-cyclic nucleotide 3'-phosphohydrolase approximately 1% of that obtained with myelin. Fraction IIA had approximately 50% the specific activity of the 2',3'-cyclic nucleotide 3'-phosphohydrolase found in myelin. Synaptic plasma membranes were prepared by lysing fraction IIB in 1 mM sodium phosphate, 0.1 mM EDTA at pH 8.5 and subjecting this preparation to centrifugation on a discontinuous sucrose density gradient. Enzymatic analysis indicated that membranes banding at the 0.6-0.8 M sucrose interface had high specific activities of plasma membrane enzymes (e.g. acetylcholinesterase, ATPase, 5'-nucleotidase). The specific activity of the (Na+ + K+)-ATPase in the purified membrane preparation was 8-fold higher than that in the original homogenate. Specific activities of various marker enzymes indicated that the composition of these membrane preparations for the most part was synaptic plasma membranes, approximately 7% mitochondrial outer membranes and 3% a membrane containing 2',3'-cyclic nucleotide 3'-phosphohydrolase activity. The polypeptide compositions of three possible contaminating membranes and of synaptic membranes were compared by electrophoresis in 6-20% gradient polyacrylamide gels in the presence of sodium dodecyl sulfate. Whereas mitochondrial and myelin membranes had distinct compositions, the compositions of the microsomal and synaptosomal plasma membranes were similar. Synaptic plasma membranes contained at least 27 polypeptides; the three major polypeptides had molecular weights of 103,000; 54,000; and 50,000. The major polypeptides of soluble synaptosomal proteins had molecular weights of 54,000 and 42,000.
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PMID:An improved method of preparing rat brain synaptic membranes. Elimination of a contaminating membrane containing 2',3'-cyclic nucleotide 3'-phosphohydrolase activity. 624 53

1. Rat isolated fat-cells were coated with rabbit anti-(rat erythrocyte) antibody and incubated with fresh guinea-pig serum for 25 min at 37 degrees C, which resulted in a more than 95% release of the cytosolic enzyme lactate dehydrogenase. 2. Under these conditions fragmentation of the plasma membrane was examined by following the plasma-membrane markers 5'-nucleotidase, adrenaline-sensitive adenylate cyclase and membrane-bound rabbit immunoglobulin G through a differential-centrifugation fractionation procedure. 3. Approx. 50% of the plasma-membrane markers remained associated with triacylglycerol. Of the remainder more than half was pelleted by centrifugation at 10 000 g for 30 min. 4. The 10 000 g supernatant was fractionated by centrifugation on a sucrose density gradient (15-50%, w/w). This procedure resulted in the production of two visible white bands on the density gradient. The bands consisted of vesicles derived from the plasma membrane, since they coincided with peaks of 5'-nucleotidase activity, contained membrane-bound immunoglobulin G and the denser one had adenylate cyclase activity. The phospholipid and protein contents of the vesicles were determined and compared with those in purified plasma membrane. 5. It is suggested that complement-mediated lysis of rat fat-cells caused the production of plasma-membrane vesicles that differ in composition from the whole plasma membrane.
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PMID:Complement-mediated production of plasma-membrane vesicles from rat fat-cells. 624 63

1. The role of adenosine deaminase (EC 3.5.4.4), ecto-(5'-nucleotidase) (EC 3.1.3.5) and ecto-(non-specific phosphatase) in the CN-induced catabolism of adenine nucleotides in intact rat polymorphonuclear leucocytes was investigated by inhibiting the enzymes in situ. 2. KCN (10mM for 90 min) induced a 20-30% fall in ATP concentration accompanied by an approximately equimolar increase in hypoxanthine, ADP, AMP and adenosine concentrations were unchanged, and IMP and inosine remained undetectable ( less than 0.05 nmol/10(7) cells). 3. Cells remained 98% intact, as judged by loss of the cytoplasmic enzyme lactate dehydrogenase (EC 1.1.1.27). 4. Pentostatin (30 microM), a specific inhibitor of adenosine deaminase, completely inhibited hypoxanthine production from exogenous adenosine (55 microM), but did not black CN-induced hypoxanthine production or cause adenosine accumulation in intact cells. This implied that IMP rather than adenosine was an intermediate in AMP breakdown in response to cyanide. 5. Antibodies raised against purified plasma-membrane 5'-nucleotidase inhibited the ecto-(5'-nucleotidase) by 95-98%. Non-specific phosphatases were blocked by 10 mM-sodium beta-glycerophosphate. 6. These two agents together blocked hypoxanthine production from exogenous AMP and IMP (200 microM) by more than 90%, but had no effect on production from endogenous substrates. 7. These data suggest that ectophosphatases do not participate in CN-induced catabolism of intracellular AMP in rat polymorphonuclear leucocytes. 8. A minor IMPase, not inhibited by antiserum, was detected in the soluble fraction of disrupted cells.
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PMID:Role of adenosine deaminase, ecto-(5'-nucleotidase) and ecto-(non-specific phosphatase) in cyanide-induced adenosine monophosphate catabolism in rat polymorphonuclear leucocytes. 624 64

Intact polymorphonuclear neutrophils were modified chemically by a poorly permeable reagent, diazotized sulfanilic acid, and the changes in the activity of 5'-nucleotidase, alkaline phosphodiesterase, and leucine aminopeptidase were examined. Among three plasma membrane enzymes, 5'-nucleotidase activity was hardly detected in the human neutrophils. The activity of alkaline phosphodiesterase was observed in all the neutrophils examined, but was not inhibited by diazotized sulfanilic acid in the guinea-pig neutrophils. On the other hand, the activity of leucine aminopeptidase was not only found but also inhibited by diazotized sulfanilic acid without the inhibition of lactate dehydrogenase, a cytosol enzyme, in all the neutrophils, suggesting that leucine aminopeptidase is located generally on the plasma membrane as an ecto-enzyme in the neutrophils.
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PMID:Leucine aminopeptidase as an echo-enzyme of polymorphonuclear neutrophils. 625 75

The effects of chronic intra-peritoneal administration of aflatoxin B1 on the activity of alkaline and acid phosphatases; glutamic oxaloacetate (GOT) and pyruvate transaminases (GPT); 5'-nucleotidase and lactic dehydrogenase enzymes were monitored in the testis and kidney of adult albino rats. Results showed that aflatoxin B1 depressed the activity of alkaline phosphatase in both tissues, but increased that of acid phosphatase in only the testis. While GOT and 5'-nucleotidase were inhibited, GPT and lactic dehydrogenase activity was enhanced by this carcinogen. These responses were similar for the testis and kidney. The above findings coupled with the microscopical observation of the testis tissue seem to indicate that the essential lesion of this toxin on the testis may be a modification of the enzymes of germinal cells resulting from a gradual depletion of the latter. Furthermore, the results appear to show that by and large, aflatoxin B1 exerts only slightly different effects on the testis and kidney at the enzyme level.
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PMID:The effects of aflatoxin B1 on some testicular and kidney enzyme activity in rat. 625 8

Enzymatic activities of thymocytes isolated from Swiss albino mice were studied at various ages from immediately post weaning until 100 weeks of age, approaching the life expectancy of these animals. Between 5 and 10 weeks of age, the activities of lactate dehydrogenase and alkaline phosphatase decreased to a level that was maintained throughout the remainder of the aging profile. Neutral beta-glycerophosphatase (pH 7.5) activity in a thymus membrane preparation was similar in all age groups. The activity of membrane-bound 5'-nucleotidase, that is, AMP-hydrolyzing activity inhibited by 100 microM alpha, beta-methyleneadenosine 5'-diphosphate, progressively increased as a function of age, indicating thymocyte population changes occurring very late in life. In thymocytes of the oldest mice examined (100 weeks of age), 5'-nucleotidase specific activity was approximately ten-fold greater than the activity found in 5-week-old mice. Thus, membrane-bound 5'-nucleotidase activity in thymocytes increased markedly as a function of age in Swiss albino mice; yet several other enzymatic activities, including alkaline phosphatase, remained relatively unchanged in mature mice.
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PMID:Age-related changes in 5'-nucleotidase and alkaline phosphatase activities in mouse thymocytes. 629 8

Fractions enriched in plasma membranes have been obtained from peripheral nerves enriched 89% in quiescent Schwann cells. Fractions were prepared from the intrafascicular tissue of desheathed distal stumps of cat sciatic nerve 8-10 weeks after transection and suture in the upper thigh. Tissue enriched in Schwann cells was minced, homogenized, and centrifuged to remove nuclei and undispersed tissue. Centrifugation of the resulting supernatant produced a pellet that was osmotically shocked, layered over a discontinuous sucrose gradient, and recentrifuged. Fractions enriched in plasma membrane (PM) markers were pooled, osmotically shocked for 16 h, layered over a second discontinuous sucrose density gradient, and recentrifuged. Membrane fractions (0.6 M:0.85 M and 0.85 M:1.0 M interfaces) contained a homogeneous population of unilamellar vesicles free of myelin. The 0.85 M fraction was enriched in 5'-nucleotidase, 2',3'-cyclic nucleotide 3'-phosphohydrolase. and specific [3H]ouabain binding, 4.8-, 3.0-, and 5.7-fold over the crude homogenate, respectively. These fractions also demonstrated low enzyme activities for succinate dehydrogenase, lactate dehydrogenase, and glucose-6-phosphatase (9, 13, and 15% of control values, respectively). Protein yield of the PM fraction (0.85 M) was approximately 0.6 mg/g of denervated nerve. This preparation should be suitable to characterize the surface properties of Schwann cells free of neuronal regulation.
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PMID:Isolation and partial characterization of plasmalemma from quiescent Schwann cells in denervated cat sciatic nerve. 630 68

Nerve terminals prepared from rat cortex and hippocampus were loaded with seven radioactive putative neurotransmitters (serotonin, noradrenaline, dopamine, gamma-aminobutyric acid, aspartate, glutamate, and taurine). The release of these transmitters, choline acetyltransferase, 3,4-dihydroxyphenylalanine decarboxylase, enolase, and lactate dehydrogenase was monitored during complement-mediated lysis. Three antisera were used: anti-5'-nucleotidase, anti-Chol-1, and anti-rat cerebrum. Anti-5'-nucleotidase serum did not cause the release of any labelled transmitter or of any of the enzymes studied. Anti-Chol-1 serum released choline acetyltransferase and small amounts of enolase and lactate dehydrogenase. Anti-rat cerebrum caused the release of all seven transmitters, choline acetyltransferase, and small amounts of the other three enzymes. It was concluded that 5'-nucleotidase was not present on any of the terminals studied, and that Chol-1 is only present on cholinergic terminals.
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PMID:Presynaptic distribution of the cholinergic-specific antigen Chol-1 and 5'-nucleotidase in rat brain, as determined by complement-mediated release of neurotransmitters. 630 66

By means of DEAE-Sephadex A-50 column chromatography and gel filtrations on Sephadex G-75, Sephacryl S-300 and Sephadex G-100, successively, a potent 5'-nucleotidase was purified from Trimeresurus gramineus venom. The venom 5'-nucleotidase is a single polypeptide chain and homogeneous as judged by SDS-polyacrylamide gel electrophoresis. It is a thermostable glycoprotein consisting of 589 amino acid residues. Its molecular weight was estimated to be 74,000 by SDS-polyacrylamide gel electrophoresis. It possessed nucleotidase activities toward adenosine monophosphate and adenosine diphosphate. The specific activities toward AMP and ADP were 504 +/- 28 and 101 +/- 8 micrograms Pi/min per mg, respectively. Pre-incubation of this venom's 5'-nucleotidase with ADP resulted in the cleavage of ADP and formation of adenosine. The 5'-nucleotidase activity was inhibited by EDTA. Both Zn2+ and Co2+/- reversed the inhibitory effect of EDTA. In rabbit platelet-rich plasma, it inhibited completely the ADP (2 x 10(-5) g/ml)-induced platelet aggregation. It also inhibited the platelet aggregations induced by sodium arachidonate (100 microM), collagen (20 micrograms/ml) and ionophore A-23187 (5 microM)-induced platelet aggregations were not affected significantly by this venom 5'-nucleotidase. In ADP-refractory platelet-rich plasma, the venom 5'-nucleotidase inhibited the platelet aggregations induced by collagen (20 micrograms/ml) or sodium arachidonate (100 microM). The venom 5'-nucleotidase showed a more pronounced inhibitory effect on sodium arachidonate-induced platelet aggregation than creatine phosphate/creatine phosphokinase and apyrase did. No lactate dehydrogenase was released by this venom 5'-nucleotidase, indicating that no platelet lysis occurred. It is concluded that removal of ADP, which is released by these platelet aggregation inducers, and the subsequent accumulation of adenosine are responsible for the inhibitory effect of the venom 5'-nucleotidase on platelet aggregations.
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PMID:Inhibition of platelet aggregation by 5'-nucleotidase purified from Trimeresurus gramineus snake venom. 631 33

Androgen binding activity was evaluated in different subcellular particulate fractions obtained by differential centrifugation of 32-day-old rat seminiferous tubules homogenates. After eliminating heavy particles by centrifugation at 4300 g during 4 min in 0.25 M sucrose buffer, a 27,000 g pellet was obtained and layered on 1.05 M sucrose buffer. The relatively light particulate interface (LPF) formed during centrifugation at 27,000 g 60 min, showed the highest androgen binding activity among particulate fractions. This binding was associated with the plasma membrane marker 5'-nucleotidase and it did not follow any of six other subcellular structure markers: DNA for nuclei, succinate dehydrogenase for mitochondria, acid phosphatase for lysosomes, NADPH-cytochrome C reductase for smooth endoplasmic reticulum, RNA for rough endoplasmic reticulum and lactate dehydrogenase for cytosol. In LPF, concentrations of sites were estimated to be 328 +/- 54 fmol per mg proteins and affinity constant 0.78 +/- 0.23 10(9) M-1. Heat stability, steroid specificity, affinity constant and rate of dissociation were similar to the well known androgen binding protein, ABP. Presence of ABP or a similar protein in subcellular particles might play a role in the mechanism of action of androgens in seminiferous tubules of maturing rats.
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PMID:Androgen binding to subcellular particles of rat testis. 710 3


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