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 in vitro effects of piperine on three bioenergetic reactions namely, oxidative phosphorylation, ATPase activity and calcium transport by isolated rat liver mitochondria have been investigated. Piperine was found to inhibit state 3 and DNP-stimulated respiration by mitochondria respiring with glutamate plus malate or succinate as substrates. The I50 values of piperine on oxidative phosphorylation in the presence of glutamate plus malate and succinate were 22 and 12 micrograms/mg mitochondrial protein respectively. With HTM preparations, the oxidation of added NADH and succinate was depressed by piperine while ascorbate plus TMPD oxidation was slightly affected. Piperine did not inhibit the mitochondrial ATPase activity induced by DNP, but by itself exerted stimulating activity on this enzyme. Piperine was also found to diminish calcium uptake and to facilitate the release of accumulated calcium by the mitochondria incubated with succinate or ATP. These results suggest that piperine inhibits mitochondrial oxidative phosphorylation at the level of respiratory chain, and the inhibitory site(s) is in the segment(s) ahead of cytochrome C. The mechanism of the piperine-induced ATPase activity is not known; but the effect of piperine on calcium transport is likely to be consequential to the effects of this compound on the mitochondrial respiratory chain and ATPase activity.
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PMID:Effects of piperine on bioenergetic functions of isolated rat liver mitochondria. 296 41

Calciosomes are small cytoplasmic vacuoles identified in various nonmuscle cell types by their content of protein(s) similar to calsequestrin (CS), the Ca2+ storage protein of the muscle sarcoplasmic reticulum (SR). These entities have been interpreted as the "primitive" counterpart of the SR, and suggested to be the organelle target of inositol-1,4,5-triphosphate action (Volpe, P., K. H. Krause, S. Hashimoto, F. Zorzato, T. Pozzan, J. Meldolesi, and D. P. Lew. Proc. Natl. Acad. Sci. USA. 85:1091-1095). Immunoperoxidase and immunogold experiments carried out in both thick and ultrathin cryosections of rat hepatocytes and pancreatic acinar cells by using antimuscle CS antibodies revealed a specific labeling widely distributed in the entire cytoplasm, while nuclei were negative. Individual calciosomes appeared as small (105 nm) membrane-bound vacuoles intermingled with, and often apposed to ER cisternae and mitochondria. Other calciosomes were scattered in the Golgi area, in between zymogen granules and beneath the plasma membrane. The cumulative volume of the CS-positive organelles was measured to account for the 0.8 and 0.45% of the cytoplasm in liver and pancreas cells, respectively. The real total volume of the calciosome compartment is expected to be approximately twice as large. In hepatocytes, structures similar to CS-positive calciosomes were decorated by antibodies against the Ca2+ ATPase of muscle SR, while ER cisternae were not. By dual labeling, colocalization was revealed in 53.6% of the organelles, with 37.6% positive for the ATPase only. CS appeared preferentially confined to the content, and the Ca2+ ATPase to the contour of the organelle. The results suggested a partial segregation of the two antigens, reminiscent of their well-known segregation in muscle SR. Additional dual-label experiments demonstrated that hepatic calciosomes express neither two ER markers (cytochrome-P450 and NADH-cytochrome b5 reductase) nor the endolysosome marker, luminal acidity (revealed by 3-[2,4-dinitroanilino]-3'-amino-N-methyl dipropylamine). Calciosomes appear as unique cytological entities, ideally equipped to play a role in the rapid-scale control of the cytosolic-free Ca2+ in nonmuscle cells.
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PMID:Immunocytochemistry of calciosomes in liver and pancreas. 297 58

A rat brain P3 fraction enriched in ER derived microsomes was centrifuged through a 20-40% linear sucrose gradient in a Beckman Ti-14 Zonal rotor and 11 fractions were obtained. The distribution of marker enzyme activities and protein were determined in these 11 subfractions. NADPH-Cytochrome C reductase, choline phosphotransferase were employed for endoplasmic reticulum, Na+,K+-ATPase, 5'-nucleotidase, and acetylcholinesterase were employed for plasma membrane, 2',3'-cyclic nucleotide phosphohydrolase was employed for myelin. The bulk of the protein was recovered in the 24-34% sucrose fractions, Na+,K+-ATPase, 5'-nucleotidase, and acetylcholinesterase were in the 22-38% sucrose fractions while NADPH-cytochrome C reductase and CNPase were enriched in the 20-22% sucrose fractions. The ethanolamine and the serine base exchange activities had a bimodal distribution, with highest specific activities in sucrose fractions 32-34% and 20-24%. Choline base exchange activity was nearly undetectable in all the fractions. The specific activities of CDP-choline phosphotransferase, and phospholipid-N-methyltransferase were highest in the 20-22% sucrose fraction. Phospholipid-N-methyltransferase activity was significantly stimulated in the presence of exogenous phospholipid acceptors as phosphatidylethanolamine or phosphatidylmonomethylethanolamine or phosphatidyldimethylethanolamine, however, the greatest response was with phosphatidylmonomethylethanolamine. The rat brain P3 fraction yielded a population of a membrane at the light end of the sucrose gradient which has a buoyant density similar to myelin but seemed to be enriched with NADPH cytochrome C reductase and phospholipid modifying enzymes. This is in contrast to liver microsomes submitted to a similar fractionation.
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PMID:Distribution of selected phospholipid modifying enzymes in rat brain microsomal subfractions prepared by density gradient zonal rotor centrifugation. 298 22

The redox states of cytochromes a(a3), b and c + c1 were continuously measured on the surface of the perfused bullfrog brain with the aid of a scanning spectrophotometer. To correlate with changes of the redox state, electrical activity was simultaneously recorded in the vicinity of the tip of the light guide of the spectrophotometer. In most cases, parallel reduction of the cytochromes was recorded in concordance with burst activity when the third or the fourth dorsal root of the spinal cord was electrically stimulated for 2 min. Recurrent cytochrome reduction and burst activity were produced by stimulation for a longer period, 5 or 10 min. Both the cytochrome reduction and burst activity were abolished when 1 microM tetrodotoxin was added to the perfusing solution. These results suggest that the cytochrome reduction coinciding with electrical activity in the brain may correlate with the Na+-influx followed by the activation of Na+,K+-adenosine triphosphatase in the neurons.
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PMID:Cytochrome reduction coincides with electrical activity in perfused bullfrog brain. 299 86

A plasma membrane fraction from bovine carotid arteries has been isolated by extraction of a crude microsomal fraction with a low-ionic-strength buffer containing ATP and Ca2+. This step was followed by sucrose-density-gradient centrifugation in the presence of 0.6 M KCl. The plasma membrane vesicles were enriched 60- to 80-fold in Na+-K+-adenosinetriphosphatase, 5'-nucleotidase, and phosphodiesterase I activities. The final yields of these marker enzymes were 12-18% of the total activities in the postnuclear supernatant, and the protein yield was 100-120 micrograms/g wet wt of carotid arteries. Contamination of the plasma membrane fraction by mitochondria and sarcoplasmic reticulum was low as judged by low activities of succinate--cytochrome-c reductase and NADPH--cytochrome-c reductase, respectively. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis and immunoprecipitation with smooth muscle-specific actin antibodies showed that the plasma membrane fraction was substantially free from myosin and actin contamination. The plasma membrane vesicles accumulated Ca2+ in the presence of ATP, and the accumulation was increased by calmodulin. Ca2+ accumulated in the presence or absence of calmodulin could be released almost completely from the vesicles by the addition of the Ca2+ ionophore A23187 but not by ethyleneglycol-bis(beta-aminoethylether)-N,N'-tetraacetic acid, indicating that Ca2+ uptake in the presence of ATP is intravesicular. The effects of phosphate and oxalate on Ca2+ uptake in the plasma membranes were different from one another. Phosphate increased Ca2+ uptake in a concentration- and time-dependent manner, and the increase in Ca2+ uptake could be observed as early as 1 min. On the other hand, oxalate at concentrations up to 5 mM did not increase Ca2+ uptake significantly during the 30-min incubation. These plasma membranes can prove useful for the study of ion transport across plasma membranes, hormone binding, characterization of calcium channels, and preparation of antibodies against plasma membrane proteins.
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PMID:Isolation and characterization of plasma membranes from bovine carotid arteries. 300 86

Cell surface components probably play an important role in early embryonic development. However, hardly any information is available on the structure or regulation of expression of the corresponding genes. As a first step in approaching this issue, we devised a procedure to obtain enriched plasma membranes from embryonic Drosophila cells. Membranes are fractionated according to two independent physical parameters: size, using velocity gradient centrifugation and density, using isopicnic gradient centrifugation. The final membrane fraction is enriched by 6 to 8 fold with respect to the plasma membrane enzyme marker Na+/K+ ATPase and substantially depleted of the mitochondrial enzyme marker cytochrome C oxidase. Two-dimensional polyacrylamide gel electrophoresis of the purified membranes reveals enrichment for specific proteins and electron microscopy reveals membrane vesicles in abundance. The enriched fraction should be suitable for the preparation of antibody probes that recognize cell surface components.
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PMID:Isolation of plasma membranes from Drosophila embryos. 300 63

The non-endplate (sarcoplasmic) acetylcholinesterase (AChE) was investigated in eight different muscles of the rat. Serial consecutive sections were stained for AChE, myofibrillar ATPase (after alkaline and acid preincubation), and cytochrome C-oxidase. The following general correlation could be established: within a given muscle the sarcoplasmic AChE was highest in type IIB fibers, lowest in type I and intermediate in type IIA. Additionally, the intensity of the reaction was directly proportional to the size of the type IIA fibers. The distribution of sarcoplasmic AChE was correlated to the ATPase fiber types but was complementary to the cytochrome C-oxidase staining pattern. In single fiber preparations, accumulation of AChE at the myotendinous junction was found to occur in "cap-like" form exclusively in fibers with very low or absent sarcoplasmic AChE. To study the role of innervation in the expression of the sarcoplasmic AChE, we cross-reinnervated the extensor digitorum longus (EDL) muscle with the soleus (SOL) nerve and vice versa (X-EDL, X-SOL). In the X-EDL the sarcoplasmic AChE was transformed to that of a normal SOL as were also the ATPase and the cytochrome oxidase. Surprisingly, in the X-SOL the high AChE activity typical for a normal EDL was present after 3 weeks but decreased steadily to very low levels lacking any correlation with ATPase and cytochrome oxidase. The results suggest that the cytoplasmic AChE of the SOL muscle depends more on the load-bearing function of the muscle than on the imposed impulse pattern. There is additional evidence for a retrograde effect of the X-SOL upon its motoneurons.
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PMID:Fiber type and non-endplate acetylcholinesterase in normal and experimentally altered muscles. 300 93

Two laboratories (Borregaard et al. (1984) J. Biol. Chem. 259, 47; Ohno et al. (1985) J. Biol. Chem. 260, 2409) have reported that a b-type cytochrome (b558) was translocated into plasma membranes from specific granules in activated neutrophils. In an attempt to examine the cytochrome b translocation, porcine neutrophils were activated by treatment with surface-active agents such as myristate (MA) and phorbol myristate acetate (PMA), and then the postnuclear supernatants of both activated and unactivated cells were fractionated by Percoll density gradient centrifugation with a Zonal rotor. In activated neutrophils, high O2- generating activity was found in the plasma membrane fraction, which showed a peak of Na, K-ATPase activity as a marker enzyme. Cytochrome b558 was recovered 74 to 78% in the plasma membrane fraction and 14 to 16% in granules in either activated or unactivated cells. No change in specific content of cytochrome b558 was observed in plasma membranes before and after activation of cells. Furthermore, in both activated and unactivated cells, vitamin B12-binding protein, a specific granule marker, was mainly found in the bottom fractions and scarcely at all in plasma membranes. These results suggest that no translocation of cytochrome b558 occurs during activation of neutrophils.
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PMID:Is cytochrome b558 translocated into the plasma membrane from granules during the activation of neutrophils? 301 63

The reactions of cytochrome b561 with other redox-active components of the adrenal chromaffin granule were examined using optical difference spectroscopy. It was shown that there is no direct electron transfer between the cytochrome and dopamine beta-hydroxylase, but that in the presence of ascorbate, turnover of dopamine beta-hydroxylase causes an oxidation of the cytochrome, which is partially reversed by the action of the mitochondrial NADH:A-. oxidoreductase. Thus, these three proteins may be functionally coupled via ascorbate. A quantitative study of the relationship between the redox state of the cytochrome and the ascorbate radical concentration measured by EPR showed that ascorbate reduces the cytochrome in a one-electron transfer reaction. Generation of a proton electrochemical gradient across the granule membrane causes only a small (20 mV) increase in the cytochrome midpoint potential suggesting the cytochrome is not a proton pump. The data are consistent with a model in which cytochrome b561, by reacting with ascorbate or ascorbate free radical on either side of the granule membrane, could couple the ascorbate-consuming reaction of the dopamine beta-hydroxylase inside the chromaffin granule to the ascorbate-regenerating reaction of the NADH:A-. oxidoreductase on the outer mitochondrial membrane. The H+-ATPase of the granule membrane could both drive the flow of electrons in the direction from cytosol to granule and replenish protons consumed by the turnover of dopamine beta-hydroxylase inside the granule.
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PMID:Functional coupling between enzymes of the chromaffin granule membrane. 301 4

Experimental hyperthyroidism induced in rats by daily injections of 3,3',5,5'-tetraiode-L-thyroxine (0.5 mg/kg i.p.) for 14 days resulted in a significant increase in heart weight and heart weight/body weight ratio. Hemodynamic and morphological studies were performed in one group. Thyroxine-treated rats showed a characteristic cardiovascular hyperdynamic state, such as tachycardia and augmented rate of contraction, but no evidence of heart failure such as elevated end-diastolic pressures. The cardiac cells in hyperthyroid rats had a significantly larger diameter and more mitochondria than did those of the control rats. In another group the activities of cardiac enzymes involved in energy utilization and liberation were measured biochemically and compared with those of normal controls. Hyperthyroidism resulted in increased specific activity of cytochrome C oxidase and actomyosin ATPase in the myocardium. The specific activity of long-chain acyl-CoA synthetase, carnitine palmityl-transferase, carnitine acetyltransferase, malate dehydrogenase and citrate synthase showed a moderate to marked increment, whereas the specific activity of lactate dehydrogenase and pyruvate kinase remained at the control values. These results suggest that in hyperthyroid rat hearts the functions of both energy liberation and utilization systems are enhanced to meet the added workload. Moreover, the increased activity of the enzymes participating in fatty acid metabolism suggest that in thyroxine-induced hypertrophic and hyperdynamic rat hearts, fatty acids contribute more to the energy supply than do carbohydrates.
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PMID:Biochemical and morphological study of cardiac hypertrophy. Effects of thyroxine on enzyme activities in the rat myocardium. 315 81


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