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 activities of the adenosine-generating enzyme 5'-nucleotidase and the adenosine-degrading enzyme adenosine deaminase were determined for four regions of rat hearts prior to and following 10-60 min of ischaemia. Whereas adenosine deaminase was uniformly active throughout the heart, 5'-nucleotidase was twice as active in atrial than in ventricular myocardium, and more active in the right than in the left ventricles in normoxic tissues. In isolated heart preparations normoxic perfusion decreased adenosine deaminase and increased 5'-nucleotidase activity compared to levels in vivo. Global ischaemia for 10 min elevated adenosine deaminase activity but had no effect on 5'-nucleotidase activity. However, 30 min of ischaemia decreased 5'-nucleotidase activity by 50% in all regions of the heart. These changed levels were not altered by 10 min of reperfusion. The fall in 5'-nucleotidase activity with ischaemia occurred only in the 90% of this enzyme which is membrane-bound. The reasons for the marked differences in distribution and responses to ischaemia of these two enzymes have yet to be elucidated but metabolic inhibitors seem unlikely to be involved.
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PMID:Differences in the regional distribution and response to ischaemia of adenosine-regulating enzymes in the heart. 282 14

Hydrolysis of 5'-AMP by 5'-nucleotidase is a possible source of adenosine in the kidney. A renal membrane-bound ecto-5'-nucleotidase has been previously described. The present study deals with the catalytic properties of a 5'-AMP phosphohydrolase partially purified from high-speed supernatants of rat kidney homogenates. It exhibits phosphatase activity toward 5'-AMP, 5'-IMP, and 5'-GMP, but not toward 2'- and 3'-AMP and corresponds therefore to a 5'-nucleotidase. The hydrolysis of 5'-AMP by the soluble 5'-nucleotidase requires divalent cations. Maximal activity is reached with 10 microM of either Mn2+ or Co2+, whereas half-maximal activity is obtained with approximately 400 microM Mg2+. The soluble 5'-nucleotidase exhibits Michaelis-Menten kinetics with a Km of 9.5 microM for 5'-AMP. In the presence of 1 mM of free Mg2+, physiological concentrations of ATP provoke an increase of the Km for 5'-AMP and a decrease of Vmax. An increase of the pH of 0.4 units in the pH range 6.4-7.4 roughly doubles the rate of hydrolysis of 5'-AMP. The effects of ATP and of the pH are compatible with a role of the renal soluble 5'-nucleotidase in the hydrolysis of 5'-AMP and in the production of adenosine during hypoxia.
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PMID:An ATP-inhibited soluble 5'-nucleotidase of rat kidney. 283 Jul 90

Cytosolic 5'-nucleotidase from bovine liver has been purified to homogeneity. Two affinity chromatographies on concanavalin A and 5'AMP-Sepharose columns result in a 12,000-fold purification. The sequential elution of glycoproteins from the concanavalin-A-Sepharose column with methyl alpha-D-glucoside and methyl alpha-D-mannoside greatly increases the degree of purification of the enzyme. Polyacrylamide gel electrophoresis in the presence of sodium dodecyl sulfate shows two subunits having apparent molecular masses of 65 kDa and 57 kDa respectively, while only one band at 70 kDa is observed in the case of the membrane-bound 5'-nucleotidase. Both the Stokes radii, measured by gel exclusion HPLC, and the sedimentation coefficient, determined by density gradient ultracentrifugation, indicate that the cytosolic enzyme is a heterodimer of about 130 kDa. This contrasts with the membrane-bound 5'-nucleotidase which is a homodimer of 140 kDa. Moreover, the antibodies raised against the membrane 5'-nucleotidase inhibited the cytosolic form indicating that a common antigenic determinant(s) exists between the two isoenzymes. However, structural differences are revealed by immunoblotting. In the same way, the effect of lectins suggests that differences in the structure of the carbohydrate chains exist between the two isoenzymes. The purified cytosolic enzyme has lower affinity for the nucleotides than does the membrane enzyme. In addition, while ADP, [alpha,beta-CH2]ADP and ATP were strong competitive inhibitors of the membrane enzyme, ADP and ATP activate the cytosolic form and [alpha,beta-CH2]ADP has no effect. Moreover, two pH optima at 7.5 and 9.5 are observed in the cytosolic enzyme while only one at 7.5 occurred in the membrane form. Finally the exogenous cations, MgCl2 and MnCl2, are necessary for the maximal activity of the cytosolic but not of the membrane 5'-nucleotidase. All these observations indicate that the two isoenzymes are different.
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PMID:Purification of bovine liver cytosolic 5'-nucleotidase. Kinetic and structural studies as compared to the membrane isoenzyme. 283 Oct 62

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

The effect on protein localisation of a carboxy-terminal deletion of periplasmic UDP-glucose hydrolase (5'-nucleotidase) has been determined in vivo using immunoprecipitation. The processed form of the truncated protein was found in the periplasm; however, in contrast to the situation with the normal protein, the preprotein form of the truncated protein was also found in the periplasm. This result confirms previous semi-in vitro data and supports the suggestion that a conformational change in a membrane-bound intermediate is a normal part of the secretory pathway.
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PMID:Altered localisation of the precursor of a secreted protein in E. coli by a carboxyl-deletion. 283 84

Quantitatively, the amount of microsomes obtained using dimethyl sulfoxide is larger than that obtained from sucrose solutions (Centelles, Franco & Bozal (1986) Biol. Chem. Hoppe Seyler 367, 461-475). In this paper it is demonstrated that from a qualitative point of view they appeared to be indistinguishable with respect to molecular characteristics. Thus, both types of microsomes had the same behaviour in experiments of isopicnic ultracentrifugation with Percoll, isoelectric focusing and gel permeation. In these experiments, the 5'-nucleotidase, lactate dehydrogenase and malate dehydrogenase activities bound to the microsomal fraction were also studied. Lactate and malate dehydrogenase activities were always found in free and membrane-bound form. In contrast, 5'-nucleotidase activity was always encountered bound to microsomal membranes.
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PMID:Determination of the characteristics, properties and homogeneity of rat brain microsomes. Binding of lactate dehydrogenase, malate dehydrogenase and 5' nucleotidase to microsomal membranes. 283 90

Insulin releases inositol phosphoglycans from myocytes in culture [(1986) Science 233, 967-972], which display insulinomimetic activity. Because 5'-nucleotidase is anchored to the membrane through inositol-containing phospholipid glycans, we investigated whether insulin could release the enzyme from the membrane. Membranes prepared from hindquarter muscles of rats perfused with insulin showed a 23% decrease in 5'-nucleotidase activity. Isolated membranes from muscle exposed to insulin in vitro also showed a small but reproducible decrease (9%) in 5'-nucleotidase activity relative to unexposed controls. Phospholipase C from Staphylococcus aureus released 60% of the membrane-bound 5'-nucleotidase. We propose that insulin may activate an endogenous phospholipase C that cleaves phospholipid-glycan-anchored proteins.
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PMID:Insulin-induced decrease in 5'-nucleotidase activity in skeletal muscle membranes. 284 8

An estrogen-regulated arginine esteropeptidase is present in the immature rat uterus. The enzymatic complex consists of a membrane-bound activator and a soluble proenzyme. The activator is under strong estrogen control; its activity increases 10-fold 3 h after a single dose of 17 beta-estradiol. The subcellular localization of the activator is determined by a radioactive assay of fractions prepared by sucrose density centrifugation. The distribution of activity parallels the distribution of two plasma membrane markers, Mg2+-ATPase and 5'-nucleotidase. Electron micrographic visualization of the gradient fractions containing the activator reveals a population of vesicles 0.2-0.5 micron in diameter.
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PMID:Estradiol stimulates a uterine plasma membrane protease activator. 296 50

Specific location of 5'-nucleotidase in the heart has been uncertain, some authors citing evidence for an exclusively non-myocyte location, while other data point to the existence of cytoplasmic and membrane-bound fractions. Single myocytes isolated from mature rat heart, and free of endothelial or interstitial cells, have been used to establish that muscle cells of the myocardium are rich in 5'-nucleotidase, exhibiting activity sufficient to account for the total myocardial content of this enzyme. All 5'-nucleotidase is accessible to extracellular AMP. Inhibitors of 5'-nucleotidase and adenosine transport have been used to establish that only the adenosine component of adenine nucleotides is taken up by myocytes, but hydrolysis of AMP by 5'-nucleotidase does not commit the adenosine formed to transport across the sarcolemmal membrane. Myocytes also have ecto-phosphatases which hydrolyse ADP and ATP.
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PMID:5'-Nucleotidase activity of isolated mature rat cardiac myocytes. 298 73

Age-associated differences in the microviscosity and the activities of enzymes (Mg++-ATPase, Na+,K+-ATPase and 5'-nucleotidase) in the liver plasma membrane were investigated in male and female rats of various ages ranging from 2 to 30 months. The membrane microviscosity, as determined by fluorescence polarization using 1,6-diphenyl-1,3,5,-hexatriene (DPH) as a probe, increased progressively with age after 2 months in male rats, whereas in female rats the microviscosity began to increase only after 24 months. On the other hand, age-associated differences in the activities of membrane-bound enzymes were generally minimal or not significant with the exception of the 5'-nucleotidase activity determined at the pH 9.1, which progressively decreased with age in male rats. The Na+, K+-ATPase activity tended to decrease in both sexes. These decrements in activity did not appear to be large enough, however, to be of definitive physiological significance. These results suggest that age may change the physical-chemical and biochemical qualities of the rat's hepatocyte plasma membrane, but the relationship between the membrane microviscosity and the activities of membrane bound enzymes is not a simple parallelism.
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PMID:Physical-chemical and biochemical differences in liver plasma membranes in aging F-344 rats. 298 54


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