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)

Ultrastructural localization of nucleozidphosphatases (5'-nucleotidase, adenosin triphosphatase (ATPase) and beta-glicerophosphatase) in antral follicles of the guinea-pig ovary has been studied. Certain heterogeneity has been found in distribution of the enzymes: the cells in the follicular tunic possess the greatest 5'-nucleotidase and ATPase activity. When 5'-adenosin monophosphate (5'-AMP) is used as a substrate, the lead phosphate residue is mainly revealed in the external surface of plasmolemma and as "caps" in the margical zone of nucleoplasm. ATPase activity is chiefly observed in nucleoli of granular cells and in those of the external follicular tunic cells. Histochemical reaction with 5'-AMP proceeds most intensively in the lucid tunic and in processes of the granular cells contacting with the oocyte. A possibility is discussed on participation of the metabolic enzymes, that localize in these structures, in the mechanisms controlling the oocyte maturation.
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PMID:[Localization of nucleoside phosphatases in the antral follicle of the guinea pig ovary]. 298 84

To investigate mechanisms whereby oxidant injury of cells results in cell dysfunction and death, cultured endothelial cells or P388D1 murine macrophage-like cells were exposed to oxidants including H2O2, O2-. (generated by the enzymatic oxidation of xanthine), or to stimulated polymorphonuclear leukocytes (PMN). Although Trypan Blue exclusion was not diminished before 30 min, cellular ATP was found to fall to less than 30% of control values within 3 min of exposure to 5 mM H2O2. Stimulated PMN plus P388D1 caused a 50% fall in cellular ATP levels. During the first minutes of oxidant injury, total adenylate content of cells fell by 85%. Cellular ADP increased 170%, AMP increased 900%, and an 83% loss of ATP was accompanied by a stoichiometric increase in IMP and inosine. Calculated energy charge [(ATP + 1/2 AMP)/(ATP + ADP + AMP)] fell from 0.95 to 0.66. Exposure of P388D1 to oligomycin plus 2-deoxyglucose (which inhibit oxidative and glycolytic generation of ATP, respectively) resulted in a rate of ATP fall similar to that induced by H2O2. In addition, nucleotide alterations induced by exposure to oligomycin plus 2-deoxyglucose were qualitatively similar to those induced by the oxidant. Loss of cell adenylates could not be explained by arrest of de novo purine synthesis or increased ATP consumption by the Na+-K+ ATPase or the mitochondrial F0-ATPase. These results indicate that H2O2 causes a rapid and profound fall in cellular ATP levels similar to that seen when ATP production is arrested by metabolic inhibitors.
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PMID:Alterations in adenosine triphosphate and energy charge in cultured endothelial and P388D1 cells after oxidant injury. 299 79

Gastric mucosal damage was produced in rats after pyloric ligation by intragastric administration of 200 mg/kg aspirin diluted in 2 ml 150 mmol/l HCl. The animals in the control group received 2 ml saline solution, or submitted to pyloric ligation only. The animals were killed 4 h after the pyloric ligation, when the number and severity of gastric lesions (ulcers), and the gastric fundic mucosal level of adenosine triphosphate (ATP), adenosine diphosphate (ADP), adenosine monophosphate (AMP), cyclic adenosine monophosphate (cAMP) and lactate, were noted and measured. The adenylate pool (ATP + ADP + AMP) and the energy charge (ATP + 0.5ADP). (ATP + ADP + AMP)-1 were calculated. It was found that: the gastric H+ output decreased significantly in the pylorus-ligated plus aspirin-treated animals; the number and severity of gastric lesions increased significantly in the pylorus-ligated aspirin-treated animals; the extent of ATP transformation into the ADP decreased significantly in the pylorus-ligated aspirin-treated animals; the extent of ATP transformation into the cAMP decreased significantly during the aspirin treatment; the values of adenylate pool and of "energy charge" remained unchanged in the different groups of animals. It is concluded that: the decreased H+ output in the pylorus-ligated plus aspirin-treated group can be obtained by the decreased extent of ATP transformation into the ADP by membrane ATPase, and the biochemical changes in the gastric mucosa indicate a decreased energy turnover.
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PMID:Biochemical background of the development of gastric mucosal damage in pylorus-ligated plus aspirin-treated rats. 300 88

The structural genes for the arsenical pump of the conjugative R-factor R773 contained on a HindIII fragment of 4.3 kilobase pairs were cloned into bacteriophage M13. A series of ordered deletions was created using Bal31 digestion, and the nucleotide sequence of the operon determined. Three open reading frames for genes arsA, arsB, and arsC were found. The arsA gene encodes a hydrophilic protein of 63,169 Da with two potential adenylate-binding sites. The arsB gene encodes a potentially membrane protein of 45,577 Da. The arsC gene encodes a 15,811-Da hydrophilic protein. The arsA and arsC gene products correspond to cytosolic proteins previously identified from minicell experiments. Isolated ArsA protein was shown to bind to dye-agarose columns which act as affinity resins for nucleotide-binding proteins. A model is proposed in which these gene products form an anion translocating ATPase for extrusion of arsenite and arsenate from resistant cells.
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PMID:Nucleotide sequence of the structural genes for an anion pump. The plasmid-encoded arsenical resistance operon. 302 63

The effects of long-term thyroidectomy and of subsequent triiodothyronine administration on kidney Na-K-ATPase were studied at the level of single nephron segments and were compared to the short-term effects previously reported. After 8-11 weeks, thyroidectomy resulted in a marked decrease in Na-K-ATPase activity in all the segments of the rabbit nephron, the proximal tubule, the thick ascending limb of Henle's loop, the distal convoluted tubule and the collecting tubule. Within this delay, thyroidectomy also decreased the ouabain-insensitive Mg-ATPase activity, the basal and hormone-stimulated adenylate-cyclase activity, and the volume of tubular epithelium in all the segments where these parameters were measured. Administration of 50 micrograms/kg body weight triiodothyronine to 8-11 weeks thyroidectomized rabbits did not restore Na-K-ATPase activity in any nephron segment within 48 h. These observations are different from those reported in animals thyroidectomized only 1 week before study since, within this latter delay, thyroidectomy altered specifically Na-K-ATPase activity, this action was observed on the proximal and collecting tubules exclusively and, triiodothyronine administration corrected Na-K-ATPase alterations after 48 h. Results of the present study indicate that in the long term, thyroidectomy has a wide spectrum of renal effects which involves the whole nephron and most cellular functions. The tubular involution induced by long-term thyroidectomy is probably responsible for the inability of kidney cells to quickly increase their Na-K-ATPase activity in response to hormonal stimulation.
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PMID:Lack of stimulation of kidney Na-K-ATPase by thyroid hormones in long-term thyroidectomized rabbits. 302 28

The onset of respiration in the cyanobacteria Anacystis nidulans and Nostoc sp. strain Mac upon a shift from dark anaerobic to aerobic conditions was accompanied by rapid energization of the adenylate pool (owing to the combined action of ATP synthase and adenylate kinase) and also the guanylate, uridylate, and cytidylate pools (owing to nucleoside diphosphate and nucleoside monophosphate kinases). Rates of the various transphosphorylation reactions were comparable to the rate of oxidative phosphorylation, thus explaining, in part, low approximately P/O ratios which incorporate adenylates only. The increase of ATP, GTP, UTP, and CTP levels (nanomoles per minute per milligram [dry weight]) in oxygen-pulsed cells of A. nidulans and Nostoc species was calculated to be, on average, 2.3, 1.05, 0.8, and 0.57, respectively. Together with aerobic steady-state pool sizes of 1.35, 0.57, 0.5, and 0.4 nmol/mg (dry weight) for these nucleotides, a fairly uniform turnover of 1.3 to 1.5 min-1 was derived. All types of nucleotides, therefore, may be conceived of as being in equilibrium with each other, reflecting the energetic homeostasis or energy buffering of the (respiring) cyanobacterial cell. For the calculation of net efficiencies of oxidative phosphorylation in terms of approximately P/O ratios, this energy buffering was taken into account. Moreover, in A. nidulans an additional 30% of the energy initially conserved in ATP by oxidative phosphorylation was immediately used up by a plasma membrane-bound reversible H+-ATPase for H+ extrusion. Consequently, by allowing for energy buffering and ATPase-linked H+ extrusion, maximum P/O ratios of 2.6 to 3.3 were calculated. By contrast, in Nostoc sp. all the H+ extrusion, appeared to be linked to a plasma membrane-bound respiratory chain, thus bypassing any ATP formation and leading to P/O ratios of only 1.3 to 1.5 despite the correction for energy buffering.
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PMID:Oxidative phosphorylation and energy buffering in cyanobacteria. 302 99

Effects of hypothyroidism on heart sarcolemmal activities were examined by using membrane preparations obtained by two different methods from rats treated with propylthiouracil for 6 to 8 weeks. ATP-independent Ca2+ binding, sialic acid and phospholipid content, Ca2+ ATPase, Mg2+ ATPase and adenylate-cyclase were not altered in membranes isolated by the hypotonic shock-LiBr treatment method from hypothyroid hearts. On the other hand, depressed activities of ouabain sensitive Na+-K+ ATPase and 5'-nucleotidase were observed in this hypothyroid preparation. Sarcolemma isolated by the sucrose density gradient procedure from hypothyroid hearts exhibited lower ouabain-sensitive Na+-K+ ATPase and higher ATP-dependent Ca2+ binding as well as Ca2+ stimulated ATPase without any changes in the 5'-nucleotidase, adenylate cyclase and Mg2+-ATPase activities. The activation of ATP-dependent Ca2+ binding and Ca2+ stimulated ATPase by calmodulin in the hypothyroid preparation was greater than the control; these effects of calmodulin were blocked by trifluoperazine. The results suggest some specific changes in the heart sarcolemmal Ca2+-pump during the development of hypothyroidism.
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PMID:Sarcolemmal Ca2+-binding and enzyme activities in myocardium from hypothyroid rat. 302 94

Metabolic regulation by nucleotides has been examined in several bacteria within the context of the adenylate energy charge (EC) concept. The ECs of bacteria capable of only fermentative metabolism (Streptococcus lactis and the ATPase-less mutant Escherichia coli AN718) fell to less than 0.2 under carbon-limiting conditions, but the bacteria were able to step up the EC to greater than 0.8 upon exposure to nutrient sugars. Similarly, nongrowing E. coli 25922, whose EC had been artificially lowered to less than 0.1 by the addition of the protonophore carbonyl cyanide m-chlorophenylhydrazone (CCCP), was able to immediately step up the EC to 0.8 to 0.9 upon the addition of glucose but was unable to respond to respiratory substrates. The EC of respiring bacteria (E. coli 25922 and Pseudomonas aeruginosa 27853) fell to 0.3 to 0.4 under certain limiting growth conditions, but the bacteria also responded immediately when challenged with succinate to give EC values greater than 0.8. These bacteria could not step up the EC with respiratory substrates in the presence of CCCP. For all bacteria, the loss of the ability to step up the EC was attributable to the loss of nutrient transport function. Mixtures of viable and HOCl-killed E. coli 25922 were able to step up the EC in proportion to the fraction of surviving cells. The data indicate that nucleotide phosphorylation levels are not regulatory in nongrowing bacteria but that the EC step-up achievable upon nutrient addition may be an accurate index of viability.
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PMID:Viability and metabolic capability are maintained by Escherichia coli, Pseudomonas aeruginosa, and Streptococcus lactis at very low adenylate energy charge. 313 45

Transient kinetic studies of Mg(2+)-dependent heavy-meromyosin ATPase (adenosine triphosphatase) were done by monitoring the release of both ADP and P(i) into the reaction medium by using linked assay systems. The release of P(i) was monitored by its quantitative transfer to ADP, with concomitant reduction of NAD(+) in the presence of d-glyceraldehyde 3-phosphate, d-glyceraldehyde 3-phosphate dehydrogenase and phosphoglycerate kinase. The dissociation rates of the products, ADP and P(i), from heavy meromyosin were shown to be faster than the rate-controlling process, which occurs after the initial bond cleavage of ATP. The chromophoric ATP analogue, 6-mercapto-9-beta-d-ribofuranosylpurine 5'-triphosphate (thioATP) was used as a substrate and spectral changes associated with a single turnover of heavy meromyosin could be assigned to elementary processes of the mechanism. It was shown that the dissociation rate of thioADP was not the rate-controlling process of the thioATPase, whose catalytic-centre activity was 7.6 times that of the ATPase at pH8. The dissociation rate of ADP from heavy meromyosin was measured by using thioATP as displacing agent and was found to be 2.3s(-1), which is about 50 times the catalytic-centre activity of the ATPase at pH8. Transient kinetic studies with chromophoric adenosine phosphate analogues have general application for kinases and ATPases both in characterizing the chemical states of the intermediates and in delineating the elementary processes of the enzyme mechanism.
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PMID:Elementary processes of the magnesium ion-dependent adenosine triphosphatase activity of heavy meromyosin. A transient kinetic approach to the study of kinases and adenosine triphosphatases and a colorimetric inorganic phosphate assay in situ. 426 38

A biochemical and cytochemical study has been made of the distribution of ATPase in mature and differentiating phloem cells of Nicotiana tabacum and of the substrate specificity and effects of fixation on enzyme activity. Homogenates of unfixed leaf midveins and midveins fixed in formaldehyde-glutaraldehyde were assayed for enzyme activity by determining the amount of P(i), liberated per milligram of protein from various substrates in a 30 min period at pH 7.2. In fresh homogenates, hydrolysis of ATP was not significantly different from that of ITP, CTP, and UTP. Hydrolysis of GTP was slightly higher than that of ATP. ATP hydrolysis by fresh homogenates was 17% more extensive than that of ADP, 76% more extensive than that of 5'-AMP, and was inhibited by fluoride and p-chloromercuribenzoate (PCMB). There was little or no hydrolysis of the competitive inhibitors 2'- and 3'-AMP nor with the alternate substrates p-nitrophenylphosphate (PNP) or beta-glycerophosphate (beta-GP). In homogenates of material fixed in formaldehyde-glutaraldehyde for 1(1/4) h, ATPase activity was 13% preserved. Hydrolysis of ATP by fixed homogenates was not significantly different from that of ADP, 5'-AMP, ITP, CTP, and GTP. Hydrolysis of UTP was lower. Fluoride and PCMB inhibited fixed ATPase activity. The results of cytochemical localization experiments using a lead phosphate precipitation technique were in agreement with the biochemical results. Similar localization patterns were obtained with the nucleoside triphosphates ATP, CTP, GTP, ITP, and UTP. Activity was also localized with ADP and 5'-AMP but not with the competitive inhibitors 2'- and 3'-AMP, nor with PNP or beta-GP. Little or no reaction product was deposited in other controls incubated without substrate or with substrate plus fluoride, PCMB, or N-ethylmaleimide. ATPase activity was demonstrated chiefly at the plasma membrane of mature and differentiating phloem cells and was associated with the P-protein of mature sieve elements. It is suggested that the phloem transport system derives its energy from the demonstrated nucleoside triphosphatase activity.
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PMID:A biochemical and cytochemical study of adenosine triphosphatase activity in the phloem of Nicotiana tabacum. 427 79


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