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)

The purpose of this study was to assess cardiac adaptation to endurance training in rats. After 11 wk of progressive treadmill exercise (1 h/day), gastrocnemius cytochrome c oxidase activity was 38% higher (P less than 0.01) in the trained (n = 20) as compared to control (n = 20) rats. Cardiac Mg2+-stimulated myofibril ATPase activity (0.308 +/- 0.012 vs. 0.324 +/- 0.006 micrometer.mg-1.min-1) did not change nor was there any change in myofibril protein concentration (60.0 +/- 1.12 vs. 59.9 +/- 0.85 mg.g-1). The isolated left ventricular papillary muscle showed no significant change in time-to-peak tension (TPT) or half-relaxation time. Tension output, however, was significantly increased with training, 2.2 +/- 0.3 vs. 1.5 +/- 0.1 g.mm-2 (P less than 0.025). Furthermore, when the papillary preparations were perfused with 0.5 mM lanthanum (La3+) to displace membrane-bound Ca2+, the time course for tension decay was significantly prolonged in the trained muscles (P less than 0.001). We conclude that endurance running of this type does not necessarily increase myofibril ATPase activity or the time course of the isometric twitch of rat papillary muscle. However, tension output per unit area does increase and this appears to be due to a greater amount of Ca2+ being made available to the contractile apparatus.
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PMID:Adaptation of the rat myocardium to endurance training. 20 62

From a homogenate of rabbit colon muscle subcellular fractions were isolated by differential centrifugation. The crude microsomal fraction could be separated into subfractions, a fraction of vesicular microsomes at 35% sucrose, a fraction containing sarcolemma, mitochondrial fragments and microsomal vesicles at 35--45% sucrose and a small protein fraction at 45--55% sucrose. Their biochemical properties and their morphological characterization were investigated. The cholesterol and the phospholipid content was equally distributed between the microsomal fractions 35% and 35--45% while the RNA was localized to the mitochondria and the microsomal fraction 35%. The enzyme cytochrome c oxidase was found to be concentrated in the mitochondria while a high contamination was found in the microsomal fractions 35--45%. The NADH-oxidase activity was highest in the 35% fraction and the 5'-nucleotidase activity in the 40,000 X g supernatant. The microsomal subfractions contained the enzymes ATPase, adenylate cyclase and phosphodiesterase. In the 35% fraction Ca stimulated the hydrolysis of ATP. The binding of [3H]-ouabain and the incorporation of [3H]-leucine was most pronounced in the 35% fraction. In a K+-free Krebs Ringer medium the binding of the glucoside was stimulated in all the fractions. From these results we concluded that the fraction 35% sucrose may be mainly derived from the endoplasmic reticulum and the plasma membrane while the 35--45% originates from the plasma membrane, mitochondria and to a lesser extent the endoplasmic reticulum.
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PMID:Biochemical and morphological characterization of subcellular fractions isolated from rabbit colon muscle. 20 90

1. Both valinomycin and p-trifluoromethoxy carbonyl cyanide phenylhydrazone (FCCP) are required for full release of respiration by cytochrome c oxidase-containing proteoliposomes (prepared by sonicating beef heart cytochrome aa3 in salt solution with 4 parts phosphatidylcholine, 4 parts phosphatidylethanolamine and 2 parts cardiolipin) in the presence of external ascorbate and cytochrome c. In the absence of valinomycin the response to FCCP is rather sluggish, as reported by Wrigglesworth et al. (1976) (Abstracts, 10th Int. Congr. Biochem., No. 06-6-230). 2. The Km for cytochrome c in 67 mM, pH 7.4, phosphate buffer with ascorbate as substrate, was 9 micrometer in both absence and presence of valinomycin and FCCP. Energization thus acts non-competitively towards cytochrome c oxidation. 3. The apparent Km for oxygen is greater in the energized than in the deenergized state; double reciprocal plots of respiration rate versus oxygen concentration are concave downward in the absence of uncouplers, as found with intact mitochondria. Energization thus acts "competitively" towards oxygen. 4. Despite the lack of a functional ATPase system, all the kinetic features of energization found in intact mitochondria can be mimicked in the reconstituted liposomes. This supports the chemiosmotic idea that electrical and perhaps H+ gradients modify the oxidase activity in reconstituted vesicles.
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PMID:Control of respiration in proteoliposomes containing cytochrome aa3. I. Stimulation by valinomycin and uncoupler. 20 20

The kinetics of CO binding by the cytochrome c oxidase of pigeon heart mitochondria were studied as a function of membrane energization at temperatures from 180 to 280 degrees K in an ethylene glycol/water medium. Samples energized by ATP showed acceleration of CO binding compared to those untreated or uncoupled by carbonylcyanide p-trifluoromethyoxyphenylhydrazone but only at relatively low temperatures and high CO concentrations. Experiments using samples in a "mixed valency" (partially oxidized) state showed that the acceleration of ligand binding is not due to the formation of a partially oxidized state via reverse electron transport. It is concluded that in the deenergized state one CO molecule can be closely associated with the cytochrome a3 heme site without actually being bound to the heme iron; in the energized state, two or more ligand molecules can occupy this intermediate position. The change in the apparent ligand capacity of a region near the heme iron in response to energization is evidence for an interaction between cytochrome oxidase and the ATPase system. Furthermore, these results suggest a control mechanism for O2 binding.
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PMID:The effect of mitochondrial energization on cytochrome c oxidase kinetics as measured at low temperatures. I. The reaction with carbon monoxide. 20 2

Mitochondrial and microsomal fractions were isolated from guinea pig myocardium by differential pelleting. The mitochondrial fraction was subjected to analytical subfractionation by sucrose density gradient centrifugation and the gradient fractions assayed for marker enzymes for the various mitochondrial compartments, viz outer membrane (monoamine oxidase), intermembranous space (adenylate kinase), inner membrane (Mg2+-dependent ATPase and cytochrome c oxidase) and mitochondrial matrix (malate dehydrogenase), and for creatine kinase. Both creatine kinase and adenylate kinase were released by suspending the mitochondria in 50 mmol . litre-1 sodium phosphate buffer. Sonication or disruption with the detergent, digitonin released the adenylate kinase but the creatine kinase remained associated with the inner membranes. Subsequent salt treatment desorbed the creatine kinase from these membranes. It is concluded that creatine kinase is located to the outer aspect of the inner mitochondrial membrane. Analytical subfractionation of the microsomal fraction clearly resolved markers for the sarcolemma (5'-nucleotidase), outer mitochondrial membrane (monoamine oxidase) and endoplasmic reticulum (neutral alpha-glucosidase and RNA). Creatine kinase was localised in the endoplasmic reticulum particularly the smooth membranes.
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PMID:Sub-mitochondrial and sub-microsomal distribution of creatine kinase in guinea pig myocardium. 51 58

Rats subjected to physical training through swimming increased their weight at a slower rate than controls, which initially had the same characteristics. The ratio heart weight/body weight was 23% greater in the trained rats. However, the absolute weights of the hearts were only 7% greater. The ultrastructural morphometric study, backed up by and analysis of the hierarchical variance, did not reveal significant changes neither in the myofibrillar and mitochondrial volume nor in the number of mitochondria per surface unit of myocardium. Furthermore, no variations were recorded, due to training, in the amount of mitochondrial protein nor in the specific mitochondrial activities of malate dehydrogenase, cytochrome c oxidase and ATPase. It is therefore suggested that the increase in the measured parameters, due to training, is proportional to the increase in weight and size of the heart. On the other hand, the specific activity of LDH increased by 15% after the first weeks of training.
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PMID:Effects of physical training on rat myocardium. An enzymatic and ultrastructural morphometric study. 59 84

The effect of treating mitochondria with visible light above 400 nm on electron transport and coupled reactions was examined. The temporal sequence of changes was: stimulation of respiration coupled to ATP synthesis, a decline in ATP synthesis, inactivation of respiration, increased ATPase activity and, later, loss of the membrane potential. Loss of respiration was principally due to inactivation of dehydrogenases. Of the components of dehydrogenase systems, flavins and quinones were most susceptible to illumination, the iron-sulfur centers were remarkably resistant to being damaged. Succinate dehydrogenase was inactivated before choline and NADH dehydrogenase. Redox reactions of cytochromes and cytochrome c oxidase activity were unaffected. Inactivation was O2-dependent and prevented by anaerobiosis or the presence of substrates for the dehydrogenases. Light in the range 400-500 nm was most effective and the presence of free flavins greatly enhanced inactivation of all of the above mitochondrial activities. This suggests that visible light mediates a flavin-photosensitized reaction that initiates damage involving participation of an activated species of oxygen in the damage propagation.
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PMID:Damage to mitochondrial electron transport and energy coupling by visible light. 65 6

Cells of the human line VA2-B in suspension culture have been treated with very low concentrations of ethidium bromide for the purpose of reducing the amount of mitochondrial DNA (mit-DNA) per cell. Cells maintained in the presence of 5 ng/ml ethidium bromide grew at a normal rate for three days; thereafter, their doubling time gradually increased to a stable value of about 60 h. In these cells, the rate of 3H thymidine incorporation into mit-DNA decreased very rapidly to approximately 60% of the normal, and remained thereafter at this level, while the amount of mit-DNA per cell stabilized around a level of 70--80% of the control. In cells long-term treated with 5 ng/ml ethidium bromide, the rate of mitochondrial protein synthesis was about 35% of the normal, and the cytochrome c oxidase activity about 50% of the control. Cells treated with 20 ng/ml of the drug underwent 3--4 cell doublings at control rates, then gradually stopped growing, and eventually died. In these cells, the rate of incorporation of 3H thymidine into mit-DNA was reduced to 50% of the control value after 10 min treatment with ethidium bromide, and became barely detectable after three cell doublings. At this time, the cells had on the average less than 10% of the control amount of mit-DNA, the rate of mitochondrial protein synthesis was reduced to 3% of the normal, and the specific activities of cytochrome c oxidase and rutamycin-sensitive ATPase were less than 20% of the control values. In spite of these marked changes, the cells exhibited only a 20--30% loss in cell viability, as estimated by cloning efficiency, after three days of exposure to the drug. Cells treated with ethidium bromide at 20 ng/ml for three days, and then transferred to drug-free medium, recovered a near-to-normal growth rate and cloning efficiency and a near-to-normal rate of synthesis and amount of mit-DNA in about five days.
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PMID:Reversible tenfod reduction in mitochondria DNA content of human cells treated with ethidium bromide. 73 78

Methods have been developed for the isolation on a semi-micro scale of a plasma membrane-enriched fraction from rat islets of Langerhans. An important feature of these experiments is the use of 125I-labeled wheat germ agglutinin as a specific probe for plasma membrane-containing fractions. The partly purified plasma membrane fraction had a density in sucrose of about 1.10 and was enriched in the activities of 5'-nucleotidase, alkaline phosphatase, sodium-potassium, and magnesium-dependent ATPase and adenylate cyclase. It contained only very low levels of acid phosphatase, cytochrome c oxidase, insulin, and RNA. Further purification was hampered by the relatively small amounts of fresh plasma membrane material that could be obtained from 16-24 rats in each experiment. When islets were prelabeled with radioactive fucose, the plasma membrane-enriched fraction contained radioactivity at a four- to fivefold higher specific acivity than the whole islet homogenate. Sodium dodecyl sulfate (SDS) polyacrylamide gel electrophoresis of plasma membrane-enriched fractions pooled from several experiments revealed a distinctive pattern of protein bands as compared with other less pure fractions. With respect to rapidity, apparent specificity, and easy reversibility of the labeling of the plasma membrane fraction, 125I-wheat germ agglutinin provides a highly useful tool for the detection of microgram quantities of plasma membrane components which should be applicable to many other systems as well.
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PMID:Preparation and characterization of plasma membrane-enriched fractions from rat pancreatic islets. 79 56

Mitochondrial function and structure in cirrhotic livers from humans or rats show a variety of changes as compared to control livers. Mitochondrial ATP production is reduced in rats with CCl4- or thioacetamide-induced liver cirrhosis and in rats with secondary biliary cirrhosis. Activity of the electron transport chain is decreased in rats with secondary biliary cirrhosis. In rats with CCl4-induced cirrhosis, the mitochondrial content of certain constituents of the respiratory chain (cytochrome a + a3, cytochrome b and ubiquinone) is increased and activities of cytochrome c oxidase and ATPase are elevated. Similarly, in humans with liver cirrhosis, mitochondrial cytochrome a + a3 content is elevated and has been used to assess the risk for hepatectomy. In rats with secondary biliary cirrhosis, compensatory strategies include increased mitochondrial volume per hepatocyte and possibly increased extramitochondrial ATP production (increased glycolysis). Thus, a variety of adaptive mechanisms are used to maintain mitochondrial function in cirrhotic livers.
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PMID:Adaptation of mitochondrial metabolism in liver cirrhosis. Different strategies to maintain a vital function. 129 65


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