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:3.6.1.3 (ATPase)
65,361 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

A plasma membrane fraction from bovine carotid arteries has been isolated by extraction of a crude microsomal fraction with a low-ionic-strength buffer containing ATP and Ca2+. This step was followed by sucrose-density-gradient centrifugation in the presence of 0.6 M KCl. The plasma membrane vesicles were enriched 60- to 80-fold in Na+-K+-adenosinetriphosphatase, 5'-nucleotidase, and phosphodiesterase I activities. The final yields of these marker enzymes were 12-18% of the total activities in the postnuclear supernatant, and the protein yield was 100-120 micrograms/g wet wt of carotid arteries. Contamination of the plasma membrane fraction by mitochondria and sarcoplasmic reticulum was low as judged by low activities of succinate--cytochrome-c reductase and NADPH--cytochrome-c reductase, respectively. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis and immunoprecipitation with smooth muscle-specific actin antibodies showed that the plasma membrane fraction was substantially free from myosin and actin contamination. The plasma membrane vesicles accumulated Ca2+ in the presence of ATP, and the accumulation was increased by calmodulin. Ca2+ accumulated in the presence or absence of calmodulin could be released almost completely from the vesicles by the addition of the Ca2+ ionophore A23187 but not by ethyleneglycol-bis(beta-aminoethylether)-N,N'-tetraacetic acid, indicating that Ca2+ uptake in the presence of ATP is intravesicular. The effects of phosphate and oxalate on Ca2+ uptake in the plasma membranes were different from one another. Phosphate increased Ca2+ uptake in a concentration- and time-dependent manner, and the increase in Ca2+ uptake could be observed as early as 1 min. On the other hand, oxalate at concentrations up to 5 mM did not increase Ca2+ uptake significantly during the 30-min incubation. These plasma membranes can prove useful for the study of ion transport across plasma membranes, hormone binding, characterization of calcium channels, and preparation of antibodies against plasma membrane proteins.
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PMID:Isolation and characterization of plasma membranes from bovine carotid arteries. 300 86

Within the uterine glands, the following enzymes were demonstrated by histochemical methods after 30, 58, 80, 100, and 110 d of pregnancy, respectively: beta-N-acetyl-hexosaminidase, beta-galactosidase, beta-glucuronidase, alpha-mannosidase, acid phosphatase, alkaline phosphatase, esterases, cytochrome oxidase, 5-nucleotidase, leucine aminopeptidase, adenosine triphosphatase, diaphorases (NADH, NADPH), glucose-6-phosphate dehydrogenase, 6-phosphogluconate dehydrogenase, succinate dehydrogenase, isocitrate dehydrogenase (NAD, NADP), beta-hydroxybutyrate dehydrogenase, glycero-3-phosphate dehydrogenase, NAD-glycero-3-phosphate dehydrogenase, glutamate dehydrogenase (NAD, NADP), lactate dehydrogenase. The results show that the activities of G-6-PDH, 6-PGDH, and cytochrome oxidase increase within secreting cells during the 2nd half of pregnancy. The activities of the other enzymes remained almost unchanged during the period of investigation. The description of our results distinguishes between gland neck, middle, and distal part of the secretory unit, respectively. In general, the enzyme activities are similar within the middle and distal gland segments, but lower in the epithelia of the neck region. The activity of dehydrogenases was medium to intensive within the middle and distal gland segments, but only low to medium within the neck portion. Of the hydrolases, the acid phosphatase, ATPase, leucine aminopeptidase, and beta-galactosidase demonstrated an intensive activity within activity secreting cells. The enzyme activities of the gland epithelia are compared with these of the uterine surface epithelia and the histochemical results are discussed in context with their significance in histiotrophic nutrition.
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PMID:[Enzyme histochemistry of the pig placenta. III. Histotopics of enzymes in the uterine epithelium]. 309 49

The cytochrome P-450 isozymes, cytochrome P-450 MC1 and MC2, purified from rats treated with 3-methylcholanthrene (MC), were found by immunohistochemical staining to be strongly induced in the livers of rats treated with 3,3', 4,4'-tetrachlorobiphenyl (TCBP), while the cytochrome P-450 isozymes, PB1 and PB2, purified from the livers of rats treated with phenobarbital (PB), were shown to be induced in the livers of rats treated with 2,2', 4,4', 5,5'-hexachlorobiphenyl (HCBP). The latter compound also strongly induced NADPH-cytochrome P-450-reductase. Following induction, all 5 enzymes were located preferentially in the centrilobular and midzonal region of the liver acinus. The influence of these polychlorinated biphenyls (PCBs) on diethylnitrosamine (DEN)-initiated hepatocarcinogenesis was investigated by analyzing the evolution of adenosine triphosphatase-deficient focal lesions. Whereas DEN alone produced very few islets, the administration of either PCB congener (150 mumol/kg, i.p., once weekly over a period of 8 weeks) subsequent to DEN treatment (50 ppm in the drinking water, 10 days) strongly enhanced the number of islets as well as the relative volume of liver occupied by islet tissue. These effects were evident, both 1 and 9 weeks, after cessation of PCB treatment. Unexpectedly the less persistent PCB congener, TCBP, showed a much more potent enhancing effect after the 9 weeks recovery period than did (HCBP).
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PMID:Polychlorinated biphenyls, classified as either phenobarbital- or 3-methylcholanthrene-type inducers of cytochrome P-450, are both hepatic tumor promoters in diethylnitrosamine-initiated rats. 309 31

Renal cytochrome P-450-dependent monooxygenases metabolize arachidonic acid to products some of which affect vascular tone and (Na+,K+)ATPase activity. We measured these metabolites in spontaneously hypertensive (SHR) and control normotensive Wister-Kyoto (WKY) rats. Systolic tail blood pressure in SHR increased from 112 to 202 mm Hg and in WKY from 97 to 136 mm Hg at 5 and 20 weeks respectively. Renal cortical and outer medullary microsomes were incubated with [14C]arachidonic acid; metabolites formed via the cytochrome P-450 pathway were defined as those dependent on NADPH, inhibited by SKF-525A, and unaffected by indomethacin. The P-450-dependent metabolites were higher in SHR vs WKY at 5, 7 and 11 weeks in the cortex and at 7 and 11 weeks in the outer medulla. In the outer medulla, the formation of these metabolites peaked at 7 weeks. Using reverse-phase HPLC, the cytochrome P-450-dependent metabolites were separated into three radioactive peaks: peak I had a retention time of 17.5 min and comigrated as 11,12-dihydroxyeicosatrienoic acid standard. Peak II had a retention time of 19 min and comigrated with omega-hydroxylation compounds. Peak III had a retention time of 27 min and comigrated with 11,12-epoxyeicosatrienoic acid. In the renal cortex, peak I was higher in SHR vs WKY at 5, 7, and 9 weeks and peak III at 5, 7, 9 and 11 weeks. In the outer medulla, peak I was higher in SHR at 5 and 7 weeks, and peaks II and III at 7 weeks. Cytochrome P-450 content in the renal cortex was always higher in SHR vs WKY. We conclude that renal cytochrome P-450-dependent metabolites of arachidonic acid may participate in the circulatory changes of SHR, particularly during the developmental stage.
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PMID:Renal cytochrome P-450-dependent metabolism of arachidonic acid in spontaneously hypertensive rats. 312 63

When corneal microsomes were incubated with arachidonic acid in the presence of an NADPH-generating system, two biologically active metabolites of arachidonic acid were formed. The structure of one of the metabolites, compound C, was previously reported to be 12(R)-hydroxy-5,8,10,14-eicosatetraenoic acid and was found to be a potent inhibitor of the Na+/K+-ATPase in the cornea. The second metabolite, compound D, was found to be a potent vasodilator as well as having the property of stimulating protein influx into the aqueous humor of the eye. Following purification of compound D by thin layer chromatography and high pressure liquid chromatography, it was found to lack a UV chromophore in contrast to the previously reported cytochrome P-450-dependent metabolite. Mass spectrometric analysis using positive and negative ionization modes was carried out on derivatized compound D that had been synthesized from a mixture of labeled [( 5,6,8,9,11,12,14,15-2H8]) and unlabeled arachidonic acid incubated with corneal microsomes. The novel arachidonate metabolite had abundant fragment ions consistent with compound D being a monooxygenated derivative of arachidonic acid with a hydroxyl substituent at carbon 12 of the eicosanoid backbone; only seven deuterium atoms from [2H8]arachidonate were retained in the structure. Oxidative ozonolysis yielded a product indicating that the double bonds in metabolite D resided between carbons at positions 8 and 9 and positions 14 and 15 of the 20-carbon chain. Compound D was therefore characterized as 12-hydroxy-5,8,14-eicosatrienoic acid. Model compounds were synthesized from dimethyl malate with the hydroxy at the 12 position with both the R and S absolute configuration and with all double bonds of the cis configuration. Only the 12(R) isomer was found to be a potent vasodilator and to increase aqueous humor protein concentration, suggesting that the biologically active compound D was 12(R)-hydroxy-5,8,14-(Z,Z,Z)-eicosatrienoic acid. As this compound possesses proinflammatory properties, it may play a role in the wound-healing processes of corneal injury.
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PMID:12(R)-hydroxyeicosatrienoic acid: a vasodilator cytochrome P-450-dependent arachidonate metabolite from the bovine corneal epithelium. 314 17

The interaction between pure transhydrogenase and ATPase (Complex V) from beef heart mitochondria was investigated with transhydrogenase-ATPase vesicles in which the two proteins were co-reconstituted by dialysis or dilution procedures. In addition to phosphatidylcholine and phosphatidylethanolamine, reconstitution required phosphatidylserine and lysophosphatidylcholine. Transhydrogenase-ATPase vesicles catalyzed a 20-30-fold stimulation of the reduction of NADP+ or thio-NADP+ by NADH and a 70-fold shift of the apparent equilibrium expressed as the nicotinamide nucleotide ratio [NADPH][NAD+]/[NADP+][NADH]. In both of these respects, the transhydrogenase-ATPase vesicles were severalfold more efficient than beef heart submitochondrial particles. By measuring the ATP-driven transhydrogenase and the oligomycin-sensitive ATPase activities simultaneously and under the same conditions at low ATP concentrations, i.e. below 15 microM, the ATP-driven transhydrogenase/oligomycin-sensitive ATPase activity ratio was found to be about 3. This value is consistent with the stoichiometries of three protons translocated per ATP hydrolyzed and one proton translocated per NADPH formed and with a mechanism where the two enzymes interact through a delocalized proton-motive force.
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PMID:Energy-linked nicotinamide-nucleotide transhydrogenase. Characterization of reconstituted ATP-driven transhydrogenase from beef heart mitochondria. 355 83

The expression of four cytochrome (cyt.) P-450 isoenzymes has been studied in preneoplastic and neoplastic lesions during the course of nitrosamine-induced hepatocarcinogenesis in the female Wistar rat. Following exposure to diethylnitrosamine (50 or 100 ppm in the drinking water) for 10 days, animals were taken sequentially, and the livers were analyzed for the evolution of adenosine triphosphatase deficient focal lesions. These lesions were subdivided into different phenotypes with regard to their cyt. P-450 isoenzyme expression using serial frozen sections. Our results demonstrate that about 40% of the adenosine triphosphatase-deficient lesions show concomitant alterations in their cyt. P-450 isoenzyme contents. Of these lesions, islets which are characterized by decreased levels of at least three cyt. P-450 isoenzymes show a dramatic increase in their volumetric fraction of liver tissue with progression of time. Although only very few lesions express this phenotype, the contribution to the volumetric fraction of islet tissue raises from about 2% at 10 weeks to about 60% at 35 weeks after cessation of diethylnitrosamine treatment. By contrast, lesions which express less than two alterations in cyt. P-450 isoenzyme levels develop relatively slowly. Similar results were obtained when animals were exposed continuously to diethylnitrosamine for a period of up to 8 weeks. Following treatment of islet-bearing animals with phenobarbital, an induction of cyt. P-450 isoenzymes and NADPH-cyt. P-450-reductase was observed within preneoplastic and neoplastic lesions. This induction was most pronounced in large, expansively growing nodules, a type of lesion which displayed decreased levels of these enzymes in livers of animals not treated with phenobarbital. The elevation of the cyt. P-450 isoenzymes disappeared within 2 to 3 weeks after cessation of inducer treatment. Our results indicate that a high proportion of rapidly growing lesions has assumed a constitutive deficiency in cyt. P-450 isoenzyme expression during nitrosamine-induced hepatocarcinogenesis. This deficiency, however, is not an irreversible quality, since individual cyt. P-450 isoenzymes can be markedly induced by treatment with an enzyme inducer like phenobarbital. Thus, the observed decrease in cyt. P-450 expression during development of malignancy does not result from alterations in the cyt. P-450 encoding structural genes but may rather be related to abnormalities in the function of regulatory systems of a higher order which may play a central role in the maintenance of cell homeostasis.
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PMID:Development of cytochrome P-450-altered preneoplastic and neoplastic lesions during nitrosamine-induced hepatocarcinogenesis in the rat. 356 9

Subcellular fractionation studies were performed to delineate plasma membrane and intracellular membrane populations which might be involved in intracellular Ca2+-homeostasis of rat small intestinal epithelial cells. After a low-speed supernatant fraction had been suspended in 5% sorbitol and subjected to equilibrium centrifugation in a zonal rotor, the Golgi and endoplasmic reticulum markers, galactosyltransferase and NADPH-cytochrome -c reductase, were concentrated in a density region designated Window II. The basal-lateral membrane marker (Na+-K+)-ATPase was concentrated in a higher-density region designated Window III. ATP-dependent Ca2+ transport was equally distributed between the two windows. Several membrane populations could be resolved from each window with good recovery of Ca2+-transport activity by a second density gradient centrifugation step. Second density gradient fractions were subjected to counter-current partitioning in an aqueous polymer two-phase system. Basal-lateral membranes, characterized by an 11-fold enrichment of (Na+-K+)-ATPase, contained ATP-dependent Ca2+-transport activity with Vmax = 3.7 nmol/mg per min and Km = 0.5 microM. A major Golgi-derived population exhibited Ca2+-transport activity with Vmax and Km values similar to those of the basal-lateral membranes. One membrane population, presumed to have been derived from the endoplasmic reticulum, contained Ca2+-transport activity with Vmax = 4 nmol/mg per min and Km = 0.5 microM. In addition to demonstrating that ATP-dependent Ca2+-transport activity has a complex distribution within enterocytes, this study raises the possibility that the basolateral plasma membranes might account for a relatively minor portion of the cell's Ca2+-pumping ability.
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PMID:Subcellular distribution of ATP-dependent calcium transport in rat duodenal epithelium. 375 59

Microsomal membranes isolated from sugar beet (Beta vulgaris L. var. GWD-2) storage tissue were found to contain a Na3VO4-dependent system for the oxidation of NADH. The system was demonstrated to be enzymatic in nature and specific for Na3VO4. Maximal Na3VO4-dependent NADH oxidation was observed at pH 6.5, when Na3VO4 was present at 200 microM and when NADH was present at 100 microM. The oxidation activity was insensitive to rotenone and antimycin A but was inhibited by NaN3, NaCN, and quinacrine. Sodium vanadate-dependent NADH oxidation occurred with a concomitant uptake of O2 from the assay solution. Both NADH oxidation and O2 consumption were dependent upon the presence of Na3VO4, inhibited by manganese, and preferred NADH to NADPH. Catalase prevented Na3VO4-dependent O2 consumption but accelerated NADH oxidation. The effects of manganese and catalase suggest that superoxide anion and hydrogen peroxide may be involved in this process. While it is unclear as to the physiological significance of Na3VO4-dependent NADH oxidation in plant cells, the presence of this system indicates that caution must be exercised when coupled ATPase assays depending upon NADH oxidation are used with plant membranes in the presence of Na3VO4.
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PMID:Vanadate-dependent NADH oxidation in microsomal membranes of sugar beet. 384 27

Nitrosamine-induced hepatocarcinogenesis has been used to investigate the regulation and expression of different drug-metabolizing enzymes in preneoplastic and neoplastic lesions in the female Wistar rat. The enzymes investigated were two phenobarbital-inducible cytochrome P-450 (cyt. P-450) isoenzymes (PB1 and PB2, mol. wt. 52 000 and 53 500, respectively), two 3-methylcholanthrene-inducible forms (MC1 and MC2, mol. wt. 54 500 and 57 000, respectively), NADPH-cytochrome P-450 reductase, the cytosolic glutathione transferases (GSTs) B and C and the microsomal epoxide hydrolase with broad substrate specificity (mEHb). Carcinogen-induced lesions were identified by use of the known markers of hepatocarcinogenesis adenosinetriphosphatase and gamma-glutamyl transpeptidase. While the GSTs and mEHb were increased in all preneoplastic and neoplastic lesions, the levels of the individual cyt. P-450 isoenzymes were characteristically different from each other. In many of the early ATPase deficient islets PB1 was elevated, whereas the content of the other cyt. P-450 forms and NADPH-cytochrome P-450 reductase was either unchanged or slightly lowered. At later stages of hepatocarcinogenesis PB1 returned to the levels of the surrounding tissue, while the other cyt. P-450 isoenzymes were decreased, the most prominent reduction being found in MC1. In neoplastic nodules all the cyt. P-450s and NADPH-cyt. P-450 reductase were diminished, some of them dramatically. These findings indicate that in spite of a common response of groups of P-450s to inducing agents, individual P-450 isoenzymes are also regulated separately. Moreover, the constant elevation of mEHb and GSTs in all lesions investigated in this study demonstrates that these enzymes, which are largely involved in deactivation, are regulated in a different fashion from the predominantly carcinogen-activating monooxygenases. The observed differences in enzyme pattern may provide a useful method for subdividing and categorizing preneoplastic and neoplastic lesions.
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PMID:Regulation and expression of four cytochrome P-450 isoenzymes, NADPH-cytochrome P-450 reductase, the glutathione transferases B and C and microsomal epoxide hydrolase in preneoplastic and neoplastic lesions in rat liver. 392 Dec 70


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