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 effects of feeding a 5% corn oil or coconut oil diet on the composition of hepatic phospholipid fatty acids and on hepatic mitochondrial function were studied. Male BHE weanling rats were fed a 65% starch diet containing 5% corn or coconut oil. Rats were decapitated, and hepatic tissue was used for phospholipid fatty acid analysis and for the preparation of mitochondria. Mitochondrial ATPase activity, alpha-glycerophosphate and malate-aspartate shuttle activity, and succinate- or pyruvate-supported respiration were determined. Livers from rats fed the coconut oil diet had more saturated phospholipid fatty acids than those from rats fed the corn oil diet. ATPase activity and the activity of the malate-aspartate shuttle were not affected by diet. The activity of the alpha-glycerophosphate shuttle was greater in rats fed the coconut oil diet than in rats fed the corn oil diet. Succinate-supported state 3 respiration was not affected by diet, whereas succinate-supported state 4 respiration was higher in mitochondria from rats fed coconut oil than in rats fed corn oil. Evidence of uncoupling of pyruvate-supported respiration from ATP synthesis was observed in mitochondria from rats fed coconut oil but not in rats fed corn oil. These observations suggest that the inherent tendency of the BHE rat toward looser coupling of respiration to ATP synthesis is potentiated by the feeding of the highly saturated fat, hydrogenated coconut oil.
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PMID:Diet effects on membrane phospholipid fatty acids and mitochondrial function in BHE rats. 294 79

Mammalian heart development, from the time of weaning until adulthood, is characterized by progressive and significant enhancement in functional performance. Aerobic metabolism and contractile protein ATPase activity increase in parallel with augmented cardiac function. The present studies examined the potential contribution of phosphorylcreatine shuttle enzymes to the developmentally linked alterations in heart performance. Mitochondrial ATPase specific activity was not altered between weanling and adult heart; however, creatine kinase activity was enhanced approximately threefold. Myofibrillar ATPase activity doubled over the developmental time course, while creatine kinase activity increased to an even greater extent. Enhanced myofibrillar ATPase activity was not due to alterations in either calcium sensitivity or ATPase activity measured in purified myosin. Both the mitochondrial and myofibrillar creatine kinase enzyme activities are enhanced during normal heart growth; however, relatively greater enhancement of the myofibrillar component occurs. Thus, enzymatic reactions comprising the phosphorylcreatine shuttle system are dramatically increased during normal heart development. This mechanism deserves consideration as a potentially powerful contributor to enhanced cardiac function during the perinatal period.
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PMID:Phosphorylcreatine shuttle enzymes during perinatal heart development. 295 1

Inhibition of ATPase activities by triethyltin (TET), diethyltin (DET), monoethyltin (MET), and trimethyltin (TMT) was studied in homogenates of brain and liver from adult and neonatal rats. In the adult, sensitivities were as follows: mitochondrial ATPase of liver much greater than Na+, K+-ATPase of brain approximately equal to mitochondrial ATPase of brain greater than nonspecific ATPase of brain and liver. MET did not produce significant inhibition. ATPase activities in brain and liver homogenates from TET-treated adult rats did not differ from controls. Mitochondrial ATPase in brain homogenates from 5-day-old rats was two orders of magnitude more sensitive to TET than brain homogenates from adult rats (IC50 of 2.5 microM in the 5-day-old neonate vs 260 microM in the adult). By contrast, isolated mitochondria and synaptosomal fractions from adult and neonatal brains were equally sensitive to TET (IC50 = 1-3 microM). At 10 days of age, following the onset of myelination, the IC50 for TET inhibition of brain mitochondrial ATPase increased to 71 microM. Myelin added directly to isolated mitochondria also reduced TET-induced inhibition. It is concluded that in vivo brain tin concentrations in 5-day-old rats following a neurotoxic dose of TET are sufficient to inhibit brain mitochondrial ATPase, whereas in adults, tin concentrations are insufficient for inhibition. In the adult rat, TET binding to myelin appears to prevent inhibition of brain mitochondrial ATPase, and the target of toxic action may be myelin. In the neonateal rat, TET may inhibit oxidative phosphorylation in unmyelinated brain tissue, leading to neuronal cell death.
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PMID:Alkyltin inhibition of ATPase activities in tissue homogenates and subcellular fractions from adult and neonatal rats. 296 35

Mitochondrial ATPase and adenylate kinase activity of hepatoma cells were inhibited by hematoporphyrin derivative (HPD) followed by photoirradiation. Inhibition of ATPase activity was a dose- and time-related event. Malonaldehyde (MDA) content of mitochondrial membranes was markedly increased by HPD plus light. The content of mouse liver microsomal cytochrome P-450 was greatly increased after intraperitoneal injection of HPD for 4 days (5 mg/kg/day). The liver weight, and levels of liver microsomal G-6-phosphatase, MDA and triglyceride (TG) showed no difference in treated vs. control animals. The data presented here demonstrate that mitochondria may be a sensitive site of action of HPD photosensitization, and inactivation of ATPase and adenylate kinase may be an important contributing factor to tumor cell damage and death.
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PMID:Photosensitization of mitochondrial adenosine-triphosphatase and adenylate kinase by hematoporphyrin derivative in vitro. 300 50

Endogenous enzyme activity can be readily and routinely demonstrated in ultrathin, frozen sections for electron microscopy. The procedure employed to obtain the best structural preservation as well as enzyme activity in thin sections involved fixation in glutaraldehyde, embedding in thiolated gelatin or pure gelatin, partial dehydration in glycerol, and sectioning in a cryostat at -35 degrees C with a slightly modified Porter-Blum microtome on which the tissue is maintained at -70 degrees C and the knife at -23 degrees C. Kidney cortex was used as test tissue, but a few other organs were occasionally used. Thin sections were floated on the surface of several incubation media routinely employed for enzyme cytochemistry. Positive, specific reactions were obtained for alkaline phosphatase in kidney brush border, for adenosine triphosphatase in brush border and in basal membranes of distal tubules, for acid phosphatase and esterase in lysosomes, and for NADH diaphorase in mitochondria. Mitochondrial ATPase was sporadically evident only in the distal tubule of the kidney. Localizations of enzyme activity reported by other technical approaches were confirmed and in some cases somewhat improved.
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PMID:Ultrathin frozen sections. II. Demonstration of enzymic activity. 429 6

Weanling rats were fed either high fat diets containing 40% of calories as fat or low fat diets containing 15% of calories as fat for 14 days. All diets were formulated to contain equivalent essential nutrients per calorie content for the nonfat components. For both dietary fat levels, the polyunsaturated to saturated fatty acid (P/S) ratio was adjusted by substitution of beef tallow for soybean oil to provide a dietary P/S ratio of 2.0 or 0.25. After feeding, hearts were removed from six replicate groups of animals per diet treatment, and mitochondria were isolated. Phospholipids were extracted from the mitochondrial membranes, and cardiolipin, phosphatidylcholine and phosphatidylethanolamine content were quantitatively analyzed using an iatroscanner. In addition, fatty acyl tail composition of each purified phospholipid was determined. Mitochondrial ATPase was also assessed by ATP-32Pi exchange assay. Feeding high fat diets increased phosphatidylcholine content of the mitochondrial membrane. High fat diets resulted in a relative increase in mitochondrial cardiolipin content that was apparently unaffected by the P/S ratio of the diet fed. Both the fat level in the diet and the P/S content altered ATPase activity. This composition to those potentially consumed by humans can result in alterations in membrane structural constituents of cardiac mitochondria and have potential to alter lipid-dependent functions of integral membrane proteins.
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PMID:Effect of dietary fat level and polyunsaturated fatty acid content on the phospholipid composition of rat cardiac mitochondrial membranes and mitochondrial ATPase activity. 622 13

In a previous study [Parce, Cunningham & Waite (1978) Biochemistry 17, 1634-1639] changes in mitochondrial phospholipid metabolism and energy-linked functions were monitored as coupled mitochondria were aged in iso-osmotic sucrose solution at 18 degrees C. The sequence of events that occur in mitochondrial deterioration under the above conditions have been established more completely. Total adenine nucleotides are depleted early in the aging process, and their loss parallels the decline in respiratory control. Related to the loss of total adenine nucleotides is a dramatic decrease in ADP and ATP translocation (uptake). The decline of respiratory control is due primarily to a decrease in State-3 respiration; loss of this respiratory activity can be related to the decline in ADP translocation. Mitochondrial ATPase activity does not increase significantly until State-4 respiration has increased appreciably. At the time of loss of respiratory control the ATPase activity increases to equal the uncoupler-stimulated activity. The H+/O ratio and P/O ratios do not decrease appreciably until respiratory control is lost. Similarly, permeability of the membrane to the passive diffusion of protons increases only after respiratory control is lost. There observations reinforce our earlier conclusion that there are two main phases in mitochondrial aging. The first phase is characterized by loss of the ability to translocate adenine nucleotides. The second phase is characterized by a decline in the ability of the mitochondrion to conserve energy (i.e. maintain a respiration-driven proton gradient) and to synthesize ATP.
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PMID:Deterioration of rat liver mitochondria under conditions of metabolite deprivation. 625 62

Mitochondrial ATPase inhibitor protein (IF1) reacts reversibly with complex V and inhibits up to 90% of its ATPase activity. Both the rate and extent of inhibition are pH and temperature dependent and increase as the pH is lowered from pH 8 tp 6.7 (the lowest pH examined) or as the temperature is increased from 4 to 36 degrees C. Nucleotide triphosphates plus Mg2+ ions are required for inhibition of complex V ATPase activity by IF1. In the presence of Mg2+ ions, the effectiveness order of nucleotides is ATP greater than ITP greater than GTP greater than UTP. Highly purified complex V, which requires added phospholipids for expressing ATPase and ATP-Pi exchange activities, cannot be inhibited by IF1 plust ATP-Mg2+ unless phospholipids are also added. This indicates that the active state of the enzyme is necessary for the IF1 effect to be manifested, because F1-ATPase, which does not contain nor require phospholipids for catalyzing ATP hydrolysis, can be inhibited by IF1 plus ATP-Mg2+ in the absence of added phospholipids. The IF1-inhibited complex V, but not IF1-inhibited F1-ATPase, can be reactivated by incubation at pH greater than 7.0 in the absence of ATP-Mg2+. The reactivation rate is pH dependent and is influenced by temperature and enzyme concentration. Complex V preparations contain small and variable amounts of IF1. This endogenous IF1 behaves the same as added IF1 with respect to conditions described above for inhibition and reactivation and can result in 25-50% inhibition in different complex V preparations. However, complex V lacking endogenous IF1 can be reconstituted from F0, F1, oligomycin sensitivity conferring protein, and phospholipids. Inhibition of this reconstituted preparation in the presence of ATP-Mg2+ depends entirely on addition of IF1. In general, the ATP-Pi exchange activity of complex V is more sensitive to the chemical inhibitors of F1-AtPase tha its ATPase activity. This is not so, however, for IF1. Under conditions that IF1 caused approximately 75% inhibition of ATPase activity of complex V, no more than 10% of the ATP-Pi exchange activity was inhibited.
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PMID:Mitochondrial adenosinetriphosphatase inhibitor protein: reversible interaction with complex V (ATP synthetase complex). 626 16

Left anterior descending coronary artery occlusion in anesthetized pigs produced a stable transmural ischemia characterized by a rapid and then sustained loss of blood flow and mechanical function. After 2 h of occlusion, mitochondria from the ischemic area exhibited a 36 +/- 6% drop in state 3 respiratory activity (QO2) supported by the NAD-linked substrates, glutamate plus malate, but only a 5 +/- 3% decrease in QO2 with succinate plus rotenone. The activity of electron transfer complex I (NADH-CoQ reductase) decreased commensurately by 33 +/- 4% with the decrease in QO2 with NAD-linked substrates. Consistent with the nearly unchanged QO2 with succinate plus rotenone, the activities of electron transfer complexes III and IV decreased only slightly by 9 +/- 5% and 9 +/- 4%, respectively. Mitochondrial ATPase (complex V) activity decreased by 48 +/- 2% with little change in its oligomycin sensitivity. A 48% drop in ATPase activity was shown, by means of oligomycin titrations, to correspond to a 32% decrease in NAD-linked substrate supported QO2. The decreases observed in NADH-CoQ reductase and ATPase activities each account nearly quantitatively for the impaired mitochondrial phosphorylating respiration observed during sustained myocardial ischemia. These results suggest that mitochondrial inner enzyme complexes I and V are important sites of cellular injury in myocardial ischemia.
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PMID:Mitochondrial inner membrane enzyme defects in porcine myocardial ischemia. 645 Nov 85

Mitochondrial adenosine triphosphatase (ATPase) of the ciliate protozoon Tetrahymena pyriformis ST is completely inhibited by antiserum prepared against F1-ATPase purified from Schizosaccharomyces pombe, and by naturally occurring inhibitor proteins from this yeast and from bovine heart mitochondria. An ATPase inhibitor protein is also present in extracts of T. pyriformis. Mitochondrial ATPase of T. pyriformis is only partially inhibited by the F0-ATPase inhibitors N,N'-dicyclohexylcarbodiimide, oligomycin, leucinostatin, triethyltin sulphate and venturicidin, and (at high titres) by the F1-ATPase inhibitors Dio-9, efrapeptin, 4-chloro-7-nitrobenzofurazan and spegazzinine. Aurovertin, citreoviridin and quercetin were not inhibitory. Resistance to inhibitors distinguishes this mitochondrial ATPase from all those previously examined.
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PMID:Effects of inhibitors on mitochondrial adenosine triphosphatase of Tetrahymena pyriformis ST. 646 27


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