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)

Detergent extracts of isolated rat liver plasma membranes were analysed in two-dimensional immunoelectrophoresis against antiserum to plasma membranes. Enzyme staining of the immunoprecipitates revealed the presence of about ten antigens with nucleoside di- and triphosphatase activity. Most of these were earlier shown also to be NADH-neotetrazolium reductase active. In addition, two of these antigens exhibited L-leucyl-beta-naphthylamidase activity. As judged from autoradiography these plasma membrane antigens earlier characterized as multienzyme complexes bound [14C]epinephrine, and the same antigens were labelled regardless of whether membranes or membrane extracts were incubated with the radioactive hormone. The specificity of this binding was established in displacement experiments with unlabelled hormones or their analogues. Another hormone-binding antigen, also identified in the plasma membrane extract did not exhibit any known enzyme activity while three antigens with different enzyme activities had no epinephrine-binding capacity. [14C]Epinephrine-labelled plasma membrane extracts were chromatographed on Sepharose 4B and the fractions obtained were analysed in two-dimensional immunoelectrophoresis combined with autoradiography. Nucleoside di- and triphosphatases of high molecular weights (5000000) were associated with L-leucyl-beta-naphthylamidase activity, while no such associations were detected in a lower molecular weight region (70000). Further immunological studies on the various fractionated antigens provided evidence that at least two of them occurred in both low and high molecular weight fractions. Hormone-binding membrane components in varying concentrations were found throughout the eluted extract.
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PMID:Epinephrine-binding plasma-membrane antigens in rat liver. 17 Jan 4

Plasma membranes were isolated from the yeast and mycelial forms of Candida albicans as described previously (Marriott, 1975) and examined for the presence of several enzymes. Measurement of specific activities showed enrichment of Mg2+-dependent and Ma+/K+-stimulated Mg2+-dependent adenosine triphosphatase and mannan synthetase, in the plasma membrane fractions from both morphological forms of the organism. However, acid and alkaline phosphatase, NADH oxidase and 5'-nucleotidase showed no such specific location.
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PMID:Enzymic activity of purified plasma membranes from the yeast and mycelial forms of Candida albicans. 17 Mar 63

Rhodopseudomonas palustris is grown photosynthetically on thiosulfate. As pointed out earlier, the chromatophore deficient cell-free fraction S-144,000 catalyzes the thiosulfate-linked ATP-dependent reversal of electron transfer in anaerobiosis, thus providing reducing equivalents in the form of NADH. Under aerobic conditions, this fraction also catalyzes the oxidation of NADH, ferro-cytochrome c, or ascorbate. ATP, ADP, and PPi are active in retarding the aerobic electron flow. The electron retardation is stimulated by the addition of Mg2+ due to a Mg2+-stimulated ATPase present. The ATPase system in S-144,000 hydrolyzes ATP, ADP, and PPi. Similarly, ATP or ADP, or even PPi can function as energy sources in order to achieve the reduction of pyridine nucleotide. The ATPase turnover is diminished by NADH or NAD+. Admixture of ascorbate results in an increased ATPase activity. Exactly the enhanced amount of adenine nucleotide hydrolysis caused by the addition of ascorbate is inhibited by cyanide.
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PMID:Respiratory electron flow and ATPase system in photosynthetically grown Rhodopseudomonas palustris. 17 Jul 51

1. Functional properties of the ATPase complex are investigated in megamitochondria isolated from livers of weanling mice fed a diet containing 2% chloramphenicol, as an inhibitor of mitochondrial protein synthesis. 2. Whereas the specific activity of ATPase remains unchanged in chloramphenicol-induced megamitochondria, about 40% of the enyzme activity is resistant to inhibition by oligomycin, triethyltin or venturicidin. It is concluded that the ATPase complex lacks one or more components whose synthesis or accumulation is dependent on mitochondrial translation. The inhibitor-resistant ATPase portion appears tightly bound to the mitochondrial membrane. 3. Respiratory chain phosphorylation is tightly coupled in isolated megamitochondria. ATP synthesis and ATP-Pi exchange are diminished by 40%, as compared to control mitochondria, but both processes are sensitive to oligomycin, triethyltin or venturicidin. 4. The decrease in ATP synthesis and ATP-Pi exchange in megamitochondria correlates quite well with the emergence of inhibitor-resistant ATPase. 5. The following electron transport activities in the megmitochondria are reduced: NADH-cytochrome c reductase, by 60%, cytochrome oxidase, by 80%; the amount of antimycin required to gain complete inhibition of the bc1-segment is diminished by more than 50%. On the other hand succinate dehydrogenase activity is increased by 50%. 6. Chloramphenicol-induced megamitochondria appear to be a useful system for studying the role of mitochondrial translation in the assembly of mammalian mitochondria.
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PMID:ATPase complex and oxidative phosphorylation in chloramphenicol-induced megamitochondria from mouse liver. 17 30

Biopsies from vastus lateralis muscle of male patients suffering from chronic ethanol abuse were studied with regard to histochemical reactions of ATPase and NADH-diaphorase; enzymatic activities of triosephosphate dehydrogenase (TPD), lactate dehydrogenase (LD), and cytochrome c oxidase (cytox); content of ATP, creatine phosphate, and glycogen; and volume fractions of fat, mitochondria, and fibrillar and extrafibrillar space. The results were compared with those from controls without known abuse of ethanol. The relative numbers of fibers were the same in two groups, but the size of the fast-twitch-glycolytic (white) fibers was diminished in the alcoholic group. The activities of TPD and LD were diminished in skeletal muscle of the alcoholics. This is most probably caused by the reduced amount of fast-twitch-glycolytic tissue, as there was a good correlation between this amount and the activity of the two enzymes. The activity of cytox was slightly lower in muscle of the alcoholics than in that of the controls. The volume fraction of mitochondria was lower in the alcoholic group than in the control group. Volume fractions of fat and fibrillar and extrafibrillar space were equal in the two groups. No significant differences were found in the amount of glycogen and ATP in the muscle of the two groups. However, the content of creatine phosphate is higher in the alcoholic group than in the control group.
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PMID:Effects of chronic ethanol abuse on structure and enzyme activities of skeletal muscle in man. 17 13

Nuclei, nuclear membranes and rough endoplasmic reticulum (rER) were isolated from onion root tips and stems. Structural preservation and purity of the fractions was determined by electron microscopic and biochemical methods. Gross compositional data (protein, phospholipid, nonpolar lipids, sterols, RNA, DNA), phospholipid and fatty acid patterns, enzyme activities (ATPases, ADPase, IDPase, glucose-6-phosphatase, 5'-nucleotidase, acid phosphatase, and NADH- and NADPH-cytochrome C reductases), and cytochrome contents were determined. A stable, high salt-resistant attachment of some DNA with the nuclear membrane was observed as well as the association of some RNA with high salt-treated nuclear and rER membranes. The phospholipid pattern was identical for both nuclear and rER membranes and showed a predominance of lecithin (about 60%) and phosphatidyl ethanolamine (20-24%). Special care was necessary to minimize lipid degradation by phospholipases during isolations. Nonpolar lipids, mostly sterols and triglycerides, accounted for 35-45% of the membrane lipids. Sterol contents were relatively high in both membrane fractions (molar ratios of sterols to phospholipids ranged from 0.12 to 0.43). Sitosterol accounted for about 80% of the total sterols. Palmitic, oleic, and linoleic acids were the most prevalent acids in membrane-bound lipids as well as in storage lipids and occurred in similar proportions in phospholipids, triglycerides and free fatty acids of the membrane. About 80% of the fatty acids in membrane phospholipids and triglycerides were unsaturated. A cytochrome of the b5 type was characterized in these membranes, but P-450-like cytochromes could not be detected. Both NADH and NADPH-cytochrome c reductases were found in nuclear and rER membranes and appeared to be enriched in rER membranes. Among the phosphatases, Mg2+-ATPase and, to lesser extents, ADPase, IDPase and acid phosphatase activities occurred in the fractions, but significant amounts of monovalent ion-stimulated ATPase, 5'-nucleotidase and glucose-6-phosphatase activities did not. The results obtained emphasize that the close biochemical similarities noted between rER and nuclear membranes of animal cells extend to these fractions from plant cells.
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PMID:Characterization of nuclear membranes and endoplasmic reticulum isolated from plant tissue. 17 22

Nicotinamide adenine dinucleotides (NAD, NADH2, NADP, and NADPH2) levels decrease in myocardial dog tissue after the ligature of the coronary artery branch. The activity of a glycohydrolytic enzyme acting on NAD and releasing nicotinamide in an equivalent amount was of the same order of magnitude in infarcted tissue, irrespective of the time elapsed after the coronary artery occlusion, as it was in normal tissue. Most of the NAD contained in normal heart muscle was hydrolyzed as soon as the tissue was disrupted in a homogenizer, whereas no hydrolysis occurred when the whole fragment was incubated for 1 hour. The enzymatic activity was found mainly in a membranous fraction seperated at 17,000 x g by differential centrifugation. Acid phosphatase, K+ -activated phosphatase, and NA+-K+-ATPase specific activities were greater in this fraction. It is suggested that the structural disorganization of the heart elicited either in vitro or during the infarction process determines the conditions for a reaction between the enzyme which is localized in the membranes and the NAD which is mainly in the cytosol.
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PMID:Nicotinamide adenine dinucleotide degradation in infarcted cardiac muscle. 17 68

Three ATP-dependent reactions catalyzed by the inner membrane of rat liver mitochondria and the ATPase reaction catalyzed by purified mitochondrial ATPase (F1), were studied with respect to kinetic properties, substrates specificity, and sensitivity to bicarbonate. The ATP-dependent transhydrogenase reaction (reduction of NADP+ by NADH) catalyzed by inner membrane vesicles displays typical Michaelis-Menten kinetics in both Tris-Cl and Tris-bicarbonate buffers, with Km (ATP) values of 0.035 mM and 0.054 mM respectively. The Vmax of transhydrogenase activity (25 nmol min-1 mg-1) is the same in Tris-bicarbonate or Tris-Cl buffer. ITP and GTP readily substitute for ATP in the transhydrogenase reaction. The ATP-P1 exchange reaction catalyzed by inner membrane vesicles displays typical Michaelis-Menten kinetics in both Tris-Cl and Tris-bicarbonate buffers with Km (ATP) values of 1.0 mM and 1.4 mM respectively. The Vmax of exchange (200 nmol min-1 mg-1) is the same in either buffer. ITP and GTP do not effectively replace ATP in the exchange reaction.
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PMID:ATP-dependent reactions catalyzed by inner membrane vesicles of rat liver mitochondria. Kinetics, substrate specificity, and bicarbonate sensitivity. 17 67

It is determined that ortho- and n-nitrophenol introduced into the stomach (0.80 and 0.11 g/kg, respectively) inhibit the activity of cytochrome oxydase (by 21% at an average), cause an increase in the content of NADH (by 35 and 27%) and a decrease in ATP (by 38 and 36%, respectively), split the oxidation and phosphorylation processes in the rat liver tissue. The content of NAD+, AMP and ADP, lactate, the activity of K+, Na+-ATPase and lactate dehydrogenase do not change.
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PMID:[Peculiarities of disturbances in oxidation and phosphorylation processes in rat liver under the effect of mononitrophenols]. 17 56

1. Cells of the hydrogen bacterium Alcaligenes eutrophus are broken by gentle lysis using lysozyme treatment in hypertonic sucrose followed by osmotic shock. By this method, 93% of the in vivo activity of the H2 oxidase is recovered and the ATPase remains particle bound. In contrast, cell disruption in a French pressure cell diminishes the in vivo activity of the H2 oxidase by 50% and solubilizes the bulk of the ATPase. 2. The bacterium contains a periplasmic cytochrome c with bands at 418, 521 and 550 nm (difference spectrum). In addition to cytochrome aa3, b-560, c-553 and o, low temperature difference spectra of membranes show the presence of two further cytochromes (shoulders at 551 and 553 nm). 3. The unsupplemented membrane fraction catalyses the oxidation of hydrogen, NADH, NADPH, succinate, formate and endogenous substrate (NAD linked) at rates 2--3-fold higher than membranes obtained from cells disrupted in a French pressure cell. With the exception of the H2 oxidase all oxidase activities in lysozyme membranes are sensitive to carbonylcyanide m-chlorophenylhydrazone (20-100% stimulation of oxygen uptake). 4. The cytoplasmic fraction contains a B-type cytochrome with absorption maxima at 436 and 560 nm, capable of combining with CO; it contains non-covalently bound protohaem. In alkaline solutions a spectral transition to the haemochrome type with bands at 423, 526 and 556 nm occurs. The addition of NADH to an aerobic suspension of this cytochrome elicits new absorption maxima at 418, 545 and 577 nm (difference spectrum), which are believed to represent an oxygenated form of the reduced cytochrome.
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PMID:Respiratory components and oxidase activities in Alcaligenes eutrophus. 18 46


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