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)

Male Wistar rats fed for 60 days a glucose diet containing 17.5 mmol hexachlorobenzene/kg show a less pronounced increase in serum parameters and microsomal cytochrome P-450 concentration and a lower decrease in liver plasma membrane 5'-nucleotidase, K+, Na+- and Mg++-adenosine triphosphatase activities than the controls fed standard diet + hexachlorobenzene. Addition of 10% ethanol to the drinking water eliminates the "glucose effect". The glucose diet and ethanol exert contrasting effects on microsomal enzyme induction and liver plasma membrane damage in hexachlorobenzene intoxication.
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PMID:Interaction between glucose diet and ethanol on rat liver microsomal induction and liver plasma membrane damage in chronic hexachlorobenzene intoxication. 361 33

The rat brains homogenized with different media (sucrose, ethylene glycol, dimethyl sulfoxide and urea) yielded different amounts of microsomal fractions. The dielectric constant, density and viscosity of the homogenization media did not correlate with the amount of microsomes separated by differential centrifugation. The homogenization media containing dimethyl sulfoxide were the most efficient for the isolation of rat brain microsomes. The increase in the yield was up to 4-fold when 50% (v/v) dimethyl sulfoxide was employed. Microsomes isolated in this manner were analogous to those obtained from isotonic sucrose solution, as was demonstrated by their chemical and enzymatic (5'-nucleotidase, adenosine deaminase, guanine deaminase, purine-nucleoside phosphorylase, lactate, malate and glutamate dehydrogenases, amine oxidase fumarate hydratase, acid and alkaline phosphatase, acetylcholinesterase, NADPH-cytochrome c reductase, catalase and thiamine-diphosphatase) characterization.
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PMID:An improved method for the preparation of rat brain microsomes. 371 74

The synergistic hepatotoxicity of dietary disulfiram (DSF) with 1,2-dichloroethane (DCE) subchronically administered by inhalation at three concentration levels (150, 300, and 450 ppm) was studied. The criteria for hepatotoxicity were treatment-related increases in serum activities of sorbitol dehydrogenase, 5'-nucleotidase, and alkaline phosphatase, and in liver-to-body weight ratios. DSF alone did not elicit these responses while DCE at the highest concentration level increased liver-to-body weight ratios and the activity of 5'-nucleotidase. Exposure to DSF alone decreased cytochrome P450 levels, but in combination with DCE, the decrement of cytochrome P450 was additive in a DCE concentration-dependent manner. However, depression of cytochrome P450 by DCE alone was not concentration dependent. Although DSF and DSF/DCE combination increased the activity of glutathione S-transferases (GSTs), both DSF and DCE singly and in combination increased the tissue levels of reduced glutathione (GSH). Evidence is presented showing that the potentiation of the hepatotoxicity of DCE observed in the presence of DSF may be due to an inhibition of microsomal mixed-function oxidase-mediated metabolism of DCE and to a compensatory increase in DCE metabolism to reactive metabolites generated by GST-mediated conjugation of DCE with GSH.
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PMID:Interaction between 1,2-dichloroethane and tetraethylthiuram disulfide (disulfiram). II. Hepatotoxic manifestations with possible mechanism of action. 378 26

Subcellular fractionation techniques have been used to assess the localization of injected 125I-labeled cholera toxin (125I-CT) taken up by rat liver in vivo, and to determine whether internalization of the toxin is required for the generation of the active A1 peptide. The uptake of injected 125I-CT into the liver is maximal at 5 min (about 10% injected dose/g). At this time the radioactivity is for the most part recovered in the microsomal (P) fraction, but later on it progressively associates with the mitochondrial-lysosomal (ML) and supernatant fractions. The radioactivity is enriched 7-fold in plasma membranes at 5-15 min, and 15-60-fold in Golgi-endosome (GE) fractions at 15-60 min. On analytical sucrose gradients the radioactivity associated with the P fraction is progressively displaced from the region of 5'-nucleotidase (a plasma membrane marker) to that of galactosyltransferase (a Golgi marker). On Percoll gradients, however, it is displaced towards acid phosphatase (a lysosomal marker). Density-shift experiments, using Triton WR 1339, suggest that some radioactivity associated with the P fraction (at 30 min) and all the radioactivity present in the ML fraction (at 2 h) is intrinsic to acid-phosphatase-containing structures, presumably lysosomes. Comparable experiments using 3,3'-diaminobenzidine cytochemistry indicate that the radioactivity present in GE fractions is separable from galactosyltransferase, and thus is presumably associated with endosomes. The fate of injected 125I-labeled cholera toxin B subunit differs from that of the whole toxin by a more rapid uptake (and/or clearance) of the ligand into subcellular fractions, and a greater accumulation of ligand in the ML fraction. Analysis of GE fractions by SDS/polyacrylamide gel electrophoresis shows that, up to 10 min after injection of 125I-CT, about 80% of the radioactivity is recovered as A subunit and 20% as B subunit, similarly to control toxin. Later on there is a time-dependent decrease in the amount of A subunit and, at least with the intermediate GE fraction, a concomitant appearance of A1 peptide (about 15% of the total at 60 min). In contrast the radioactivity associated with plasma membranes remains indistinguishable from unused toxin. It is concluded that, upon interaction with hepatocytes, 125I-CT (both subunits A and B) sequentially associates with plasma membranes, endosomes and lysosomes, and that endosomes may represent the major subcellular site at which the A1 peptide is generated.
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PMID:Fate of injected 125I-labeled cholera toxin taken up by rat liver in vivo. Generation of the active A1 peptide in the endosomal compartment. 381 13

Insulin receptors in human colon tumours, normal colon tissue and mesenteric fat removed at surgery have been identified by measuring the binding of labelled insulin to cell membrane preparations. Insulin binding sites were readily detected in all tissues, with mean +/- SD binding site concentrations of 43 +/- 41, 44 +/- 39, and 44 +/- 35fmol/mg membrane protein, and dissociation constants of 0.73 +/- 0.61, 0.66 +/- 0.41, and 0.78 +/- 0.58nM for microsomal plasma membrane preparations of tumour (n = 23) respectively. The specificity of binding of labelled insulin was similar in tumour and normal colon samples. Binding in normal colon preparations was highest in the epithelium (84fmol/mg membrane protein) and lower in lamina propria (19fmol/mg), submucosa (25fmol/mg) and muscle wall (13fmol/mg). Degradation of labelled insulin was similar in tumour and normal colon preparations. Mean receptor levels were not significantly different between microsomal membrane preparations and plasma membranes partially purified on discontinuous sucrose gradients, quantitated against either unit membrane protein or unit 5'-nucleotidase specific activity. There was a significant negative correlation between insulin levels, but no significant relationship was seen between serum insulin and receptor levels in either colon tumour or tissue preparations from full-thickness normal colon wall. An inverse correlation between serum insulin and receptor levels was, however, apparent in preparations of colonic musosa. These data indicate that although insulin receptors in colon tumours share the same biochemical characteristics as those present in the normal colon, receptors in tumour tissue are less sensitive to down-regulation by ambient insulin than receptors in mesenteric fat cells and normal colonic mucosa.
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PMID:Insulin binding by normal and neoplastic colon tissue. 388 82

Thioacetamide, given intraperitoneally (1.4 mmol/kg body mass) to male Wistar rats 24 h before sacrifice promoted a marked elevation of serum aminotransferases, loss of microsomal cytochrome P-450 content and a significant reduction (about 50%) of the liver plasma membrane enzymatic activities (5'-nucleotidase; K+, Na+- and Mg2+-adenosine triphosphatases; and gamma-glutamyl transferase). Previous starvation for 48 h, immediately prior to thioacetamide administration, strongly potentiated the effects of thioacetamide on the serum, microsomal and liver plasma membrane parameters, while fasting itself did not affect them. The liver plasma membrane damage may be one of the reasons for the cell death in thioacetamide-intoxicated rat livers.
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PMID:The effect of thioacetamide on rat liver plasma membrane enzymes and its potentiation by fasting. 394 71

The aim of this study was to investigate possible mechanisms involved in the elevation of serum alkaline phosphatase activity in alcoholics. Male Sprague-Dawley rats were pair-fed nutritionally adequate liquid diets containing ethanol as 36% of energy or an isocaloric amount of carbohydrate for 4-5 wk. Serum alkaline phosphatase activity was increased moderately but significantly. Hepatocytes isolated from ethanol-fed animals exhibited pronounced morphologic alterations of their plasma membranes by scanning electron microscopy and a reduced content of alkaline phosphatase despite an increase in total liver alkaline phosphatase content. Chronic ethanol feeding also potentiated the release of alkaline phosphatase from the cells during incubation with 50 mM ethanol. Furthermore, chronic ethanol feeding resulted in reduced recovery of alkaline phosphatase in hepatic plasma membranes isolated by sucrose gradient centrifugation but did not affect the recoveries of other plasma membrane markers (5'-nucleotidase and Na+,K+-adenosine triphosphatase) nor the subcellular distribution of alkaline phosphatase in the nuclear, mitochondrial, microsomal, and cytosolic fractions. These findings suggest that the increased serum alkaline phosphatase levels observed in response to chronic ethanol feeding may be due, at least in part, to increased lability of this plasma membrane enzyme.
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PMID:Chronic ethanol consumption alters rat liver plasma membranes and potentiates release of alkaline phosphatase. 403 95

Bovine anterior pituitary glands were fractionated by differential centrifugation. T4 5'-monodeiodination to T3 was found predominantly in microsomal fractions (M2; 105,000 . g pellet) enriched in glucose-6-phosphatase and 5'-nucleotidase activities. T4 5'-deiodinase activity in M2 fraction was 85.2 fmol T3/min X mg protein and represented an 8.5-fold enrichment over homogenate specific activity (10.6 fmol T3/min . mg protein). Further subcellular localization of the T4 5'-deiodinase was effected by discontinuous sucrose density gradient centrifugation. Maximum T4 5'-deiodinase activity was found in fraction P5 at the interface of densities 1.18/1.20 (200 fmol T3/min . mg protein) and correlated with the profile of glucose-6-phosphatase and not with that of 5'-nucleotidase, the maximum activity of which was recovered in fraction P1 at the interface of densities 1.03/1.12. Electron microscopic examination of the fractions confirmed that P5 contained in excess of 90% rough membranes in contrast to 10% or less in P1. Characterization of T4 5'-deiodinase activity was carried out in M2 preparations. The reaction was thiol dependent, requiring the presence of 50 mM dithiothreitol or more (Km, 38 mM), with a maximum velocity of 55-150 fmol T3/min . mg protein (n = 8). Enzyme activity was substrate dependent, with a Km for T4 between 35-70 nM. 5'-Monodeiodination of T4 was abolished by heating to 70 C for 30 min and was unaffected by EDTA. Propylthiouracil and methimazole did not inhibit T3 generation. Iopanoic acid, on the other hand, was a competitive inhibitor of the 5'-monodeiodination reaction, abolishing T3 production in a dose-dependent manner with a Ki of 3 microM. These data indicate that the bovine anterior pituitary contains significant T4 5'-deiodinase activity, which shares many properties of the type II 5'-deiodinase of the rat. Bovine anterior pituitary T4 5'-deiodinase appears to be predominantly localized in the rough endoplasmic reticulum.
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PMID:Subcellular localization of thyroxine 5'-deiodinase activity in bovine anterior pituitary. 406 44

The series introduced by this paper reports the results of a detailed analysis of the microsomal fraction from rat liver by density gradient centrifugation. The biochemical methods used throughout this work for the determination of monoamine oxidase, NADH cytochrome c reductase, NADPH cytochrome c reductase, cytochrome oxidase, catalase, aminopyrine demethylase, cytochromes b(5) and P 450, glucuronyltransferase, galactosyltransferase, esterase, alkaline and acid phosphatases, 5'-nucleotidase, glucose 6-phosphatase, alkaline phosphodiesterase I, N-acetyl-beta-glucosaminidase, beta-glucuronidase, nucleoside diphosphatase, aldolase, fumarase, glutamine synthetase, protein, phospholipid, cholesterol, and RNA are described and justified when necessary.
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PMID:Analytical study of microsomes and isolated subcellular membranes from rat liver. I. Biochemical methods. 415 Apr 88

Liver homogenates have been submitted to quantitative fractionation by differential centrifugation. Three particulate fractions: N (nuclear), ML (large granules), and P (microsomes), and a final supernate (S) have been obtained. The biochemical composition of the microsomal fraction has been established from the assay and distribution pattern of 25 enzymatic and chemical constituents. These included marker enzymes for mitochondria (cytochrome oxidase), lysosomes (acid phosphatase and N-acetyl-beta-glucosaminidase), and peroxisomes (catalase). The microsomal preparations were characterized by a moderate contamination with large cytoplasmic granules (only 6.2% of microsomal protein) and by a high yield in microsomal components. Enzymes such as glucose 6-phosphatase, nucleoside diphosphatase, esterase, glucuronyltransferase, NADPH cytochrome c reductase, aminopyrine demethylase, and galactosyltransferase were recovered in the microsomes to the extent of 70% or more. Another typical behavior was shown by 5'-nucleotidase, alkaline phosphatase, alkaline phosphodiesterase I, and cholesterol, which exhibited a "nucleomicrosomal" distribution. Other complex distributions were obtained for several constituents recovered in significant amount in the microsomes and in the ML or in the S fraction.
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PMID:Analytical study of microsomes and isolated subcellular membranes from rat liver. II. Preparation and composition of the microsomal fraction. 415 Apr 89


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