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Query: EC:3.6.3.14 (ATP synthase)
 7,042 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

A T-to-C transition at nucleotide (nt) 9176 in the mitochondrial adenosine triphosphatase 6 (ATPase 6) gene was detected in 2 brothers with a neurological disorder resembling Leigh syndrome. The mutation was also present in the 2 other siblings and in the mother, who were asymptomatic. In the more severely affected boy (the proband), the mutation was homoplasmic in muscle, leucocytes, and fibroblasts. In leucocytes from his affected brother, 98% of mtDNA was mutant. Heteroplasmy of varying degrees was seen in leucocytes from the mother and the 2 unaffected siblings. The mutation changes a highly conserved leucine residue near the carboxyl terminus of the mitochondrial ATPase 6 subunit to proline. It could not be detected in 168 control subjects. Studies of ATP synthesis and hydrolysis in fibroblasts from the proband were normal.
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PMID:A novel mitochondrial ATPase 6 point mutation in familial bilateral striatal necrosis. 766 37

A radiation inactivation technique was employed to determine the functional size of adenosine triphosphatase from Escherichia coli (EF0EF1-ATPase). Functional units of the membrane-bound and the soluble ATPases were estimated to be 300 +/- 39 and 295 +/- 32 kDa, respectively. The presence of the free radical scavenger dithiothreitol was crucial in measuring the radiation inactivation size of ATPase. When gramicidin and carbonyl cyanide p-trifluoromethoxyphenylhydrazone were added, an increase in the functional mass of membrane-bound ATPase was observed. In contrast, valinomycin and KCl had hardly any effect on the functional size of ATPase. We also determined a functional unit of 355 +/- 33 kDa for proton translocation by a fluorescence quenching technique. A reconstitution study using irradiated coupling factor 1 (EF1)-depleted membrane revealed that the functional mass of the proton channel was 96 +/- 11 kDa. A similar functional size for ATP-Pi exchange and ATP hydrolysis implies that both reactions might utilize identical machinery. Furthermore, functional units of soluble EF1 for unisite (nonsteady state) and multisite (steady state) ATP hydrolysis were calculated as 200 +/- 32 and 298 +/- 32 kDa, respectively. A working hypothesis was proposed from radiation inactivation analysis to elucidate the structure and mechanism of F1-ATPase.
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PMID:Functional size analysis of F-ATPase from Escherichia coli by radiation inactivation. 768 67

A synthetic gene coding for the inhibitor protein of bovine heart mitochondrial F1 adenosine triphosphatase was designed and cloned in Escherichia coli. Recombinant F1-ATPase inhibitor protein was overproduced in E. coli and secreted to the periplasmic space. Biologically active recombinant F1-ATPase inhibitor protein was recovered from the bacterial cells by osmotic shock and was purified to near homogeneity in a single cation-exchange chromatography step. The recombinant inhibitor protein was shown to inhibit bovine mitochondrial F1-ATPase in a pH-dependent manner, as well as Saccharomyces cerevisiae mitochondrial F1-ATPase. Thorough analysis of the amino acid sequence revealed a potential coiled-coil structure for the C-terminal portion of the protein. Experimental evidence obtained by circular dichroism analyses supports this prediction and suggests F1I to be a highly stable, mainly alpha-helical protein which displays C-terminal alpha-helical coiled-coil intermolecular interaction.
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PMID:Recombinant bovine heart mitochondrial F1-ATPase inhibitor protein: overproduction in Escherichia coli, purification, and structural studies. 839 40

The effect of trypanosome infection on the plasma levels and ratios of tri-iodothyronine (T3) and thyroxine (T4) as well as the activity of mitochondrial adenosine triphosphatase (ATPase) were investigated. Three groups of sexually mature white New Zealand rabbits were used. Group 1 consisted of the normal non-infected rabbits, group 2 were experimentally infected with Trypanosoma congolense and group 3 were infected but given replacement doses of thyroxine. The infected animals (group 2) showed a rapid decline in both T3 and T4 but an increase in the T3/T4 ratio indicating differential production or clearance rates between the two hormones. The mitochondrial ATPase activity was found to be depressed in the infected group whereas there was no significant difference in the ATPase activity between the non-infected (group 1) and infected-treated animals (group 2). It is postulated that trypanosome induced hypothyroid status may play a role in the impairment of mitochondrial ATPase activity, a key enzyme in energy metabolism.
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PMID:Thyroid status and adenosine triphosphatase activity in experimental Trypanosoma congolense infection in rabbits. 897 23

Metal ligands of the VO(2+)-adenosine diphosphate (ADP) complex bound to high-affinity catalytic site 1 of chloroplast F(1) adenosine triphosphatase (CF(1) ATPase) were characterized by electron paramagnetic resonance (EPR) spectroscopy. This EPR spectrum contains two EPR species designated E and F not observed when VO(2+)-nucleotide is bound to site 3 of CF(1). Site-directed mutations betaE197C, betaE197D, and betaE197S in Chlamydomonas CF(1) impair ATP synthase and ATPase activity catalyzed by CF(1)F(o) and soluble CF(1), respectively, indicating that this residue is important for enzyme function. These mutations caused large changes in the (51)V hyperfine tensors of VO(2+)-nucleotide bound to site 1 but not to site 3. Mutations to the Walker homology B aspartate betaD262C, betaD262H, and betaD262T of Chlamydomonas CF(1) caused similar effects on the EPR spectrum of VO(2+)-ADP bound to site 1. These results indicate that the conversion of the low-affinity site 3 conformation to high-affinity site 1 involves the incorporation betaE197 and betaD262 as metal ligands.
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PMID:Characterization of the metal binding environment of catalytic site 1 of chloroplast F1-ATPase from Chlamydomonas. 1092 34

Nobel Prize of 1997 in chemistry was awarded to three scientists fruitfully working in bioenergetics. J. Walker and P. Boyer were awarded the Prize for studies of structure and mechanism of functioning of the H+-transporting (mitochondrial) adenosine triphosphatase. The decision of the Nobel Committee was not unexpected, since these works were very impressive. Special attention was drawn to the fact that the investigations of Walker, the recognized specialist in protein structure, made possible the experimental confirmation of regularities in the mitochondrial ATPase functioning discovered by P. Boyer. The third member of this triumph of bioenergetics is Jens-Christian Skou who described the Na+,K+-activated ATPase in 1957 and then characterized the enzyme properties in detail. Forty years of his scientific biography were devoted to this enzyme. Along with accumulation of scientific knowledge, that constituted the fundamental contribution to bioenergetics (J.Skou is rightfully considered as one of founders of this branch in the present-day biology), the world-wide known school of scientists was established, and starting from 1974, members of this school organize regular conferences on this enzyme.
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PMID:Na+,K+-ATPase: 40 years of investigations. 1096 31

The distribution of the reaction product of a staining method for adenosine triphosphatase (ATPase) in rat small intestine, kidney, and liver was studied with electron microscopy. Several procedures were tried but the best results were obtained from tissue that had been quenched in liquid nitrogen, sectioned at 25 micro in a cryostat, fixed for 30 to 90 minutes at 4 degrees C in formalin-sucrose buffered to pH 7.2, incubated with substrate, and then osmicated and prepared for electron microscopy in the usual way. This procedure enabled the localization of mitochondrial ATPase to be studied. In tissue fixed in small blocks in osmium tetroxide for 3 minutes prior to incubation with substrate, good preservation was noted, and the reaction product for ATPase was localized on the cell membrane and nuclei. The reaction product was present in abundant amount in the nuclei, and particularly within nucleoli, of all tissues studied. Because the histochemical localization of nuclear enzymes poses numerous interpretative problems at the present time, the significance of this nuclear localization is uncertain. Cell (plasma) membranes were the site of localization, especially at areas where it has been proposed that active transport mechanisms may occur, namely, on the microvilli of intestinal epithelium, endothelial lining of capillaries, glomerular epithelial cell membranes, basal infoldings of the cell membrane of renal tubules, on the microvilli of bile canaliculi, and on the microvilli of proximal convoluted tubular epithelial cells. ATPase localization on the cristae mitochondriales was also demonstrated.
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PMID:The fine structural localization of adenosine triphosphatase in the small intestine, kidney, and liver of the rat. 1396 10

Vacuolar-type H+-adenosine triphosphatase (V-ATPase) is one of the most fundamental enzymes in nature. V-ATPases are responsible for the regulation of proton concentration in the intracellular acidic compartments. It has similar structure with the mitochondrial F0F1-ATP synthase (F-ATPase). dagger The V-ATPases are composed of multiple subunits and have various physiological functions, including membrane and organelle protein sorting, neurotransmitter uptake, cellular degradative processes, and cytosolic pH regulation. The V-ATPases have been involved in multidrug resistance. Recently, plasma membrane V-ATPases have been involved in regulation of extracellular acidity, essential for cellular invasiveness and proliferation in tumor metastasis. The current knowledge regarding the structure and function of V-ATPase and its role in cancer biology is discussed.
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PMID:Plasmalemmal vacuolar-type H+-ATPase in cancer biology. 1505 22

The enzyme F1-adenosine triphosphatase (ATPase) is a molecular motor that converts the chemical energy stored in the molecule adenosine triphosphate (ATP) into mechanical rotation of its gamma-subunit. During steady-state catalysis, the three catalytic sites of F1 operate in a cooperative fashion such that at every instant each site is in a different conformation corresponding to a different stage along the catalytic cycle. Notwithstanding a large amount of biochemical and, recently, structural data, we still lack an understanding of how ATP hydrolysis in F1 is coupled to mechanical motion and how the catalytic sites achieve cooperativity during rotatory catalysis. In this publication, we report combined quantum mechanical/molecular mechanical simulations of ATP hydrolysis in the betaTP and betaDP catalytic sites of F1-ATPase. Our simulations reveal a dramatic change in the reaction energetics from strongly endothermic in betaTP to approximately equienergetic in betaDP. The simulations identify the responsible protein residues, the arginine finger alphaR373 being the most important one. Similar to our earlier study of betaTP, we find a multicenter proton relay mechanism to be the energetically most favorable hydrolysis pathway. The results elucidate how cooperativity between catalytic sites might be achieved by this remarkable molecular motor.
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PMID:ATP hydrolysis in the betaTP and betaDP catalytic sites of F1-ATPase. 1531 50

Effect of thyroidectomy (Tx) and subsequent treatment with 3,5,3'-triiodo-L: -thyronine (T(3)) or replacement therapy (T(R)) with T(3)+ L: -thyroxine (T(4)) on the temperature kinetics properties of FoF(1 )adenosine triphosphatase (ATPase, ATP synthase, H(+)-translocating ATP synthase EC 3.6.3.14) and succinate oxidase (SO) and on the lipid/phospholipid makeup of rat kidney mitochondria were examined. Tx lowered ATPase activity, which T(3) treatment restored. SO activity was unchanged in Tx but decreased further by T(3) treatment. T(R )restored both activities. The energies of ATPase activation in the high and low temperature ranges (E (H) and E (L)) increased in the Tx and T(3) animals with decrease in phase transition temperature (Tt). T(R) restored E (H) and E (L) but not Tt to euthyroid levels. E (H) and E (L) of SO decreased in Tx animals. T(3) and T(R) restored E (H) whereas E (L) was restored only in the T(R) group; Tt increased in both groups. Total phospholipid and cholesterol contents decreased significantly in Tx and T(3)-treated animals. In Tx animals, sphingomyelin (SPM) and phosphatidylcholine (PC) components decreased, while phosphatidylserine (PS) and diphosphatidylglycerol components increased. T(3) and T(R) treatments caused decreases in SPM, phosphatidylinositol and PS. PC and phosphatidylethanolamine (PE) increased in the T(3) group. T(R) resulted in increased lysophospolipids and PE. Changes in kinetic parameters of the two enzymes were differently correlated with specific phospholipid components. Both T(3) and T(R) regimens were unable to restore normal membrane structure-function relationships.
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PMID:Thyroid hormone treatments differentially affect the temperature kinetics properties of FoF1 ATPase and succinate oxidase as well as the lipid/phospholipid profiles of rat kidney mitochondria: a correlative study. 1756 78


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