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 activities of some enzymes of glycolysis, the citric acid cycle, and amino acid metabolism have been measured in the fetal guinea pig heart over the last third of gestation and correlated with heart ultrastructural development. There is little change in glycolytic enzyme activity except for a two- to threefold increase in phosphofructokinase activity. Mitochondrial content and enzyme activities are low in the early fetal heart, and, although content is similar in the late fetus and adult, enzyme activities increase twofold postnatally, indicating fetal heart mitochondria are incompletely developed. The activities of aspartate and particularly alanine aminotransferase are low in the fetal heart. Over the last third of gestation the myofibrillar content of the fetal myocyte increases twofold to the adult value by term. Associated with this is a fourfold rise in myofibrillar and sarcoplasmic reticulum Ca2+-ATPase activity. Na+-K+-ATPase activity is similar in the late fetal and adult heart but one-third lower in the early fetal heart.
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PMID:Ultrastructural and enzymatic development of fetal guinea pig heart. 621 93

Phosphorus-31 saturation transfer NMR techniques have been employed to measure the unidirectional Pi consumption rate by respiration competent suspensions of the yeast Saccharomyces cerevisiae while the levels of ATP, ADP, and Pi are constant. These experiments are performed by saturating the ATP gamma phosphate resonance and observing the changes in the Pi resonance intensity while the yeast are respiring on endogenous substrates. The unidirectional Pi consumption rate is 3.5 +/- mumol s-1 (g of wet cells)-1. The rate is reduced 10-fold upon addition of oligomycin (80 micrograms/ML), suggesting that at least 90% of the Pi consumption activity is due to the mitochondrial F1-F0 ATPase. We have not been able to conclusively assign the remaining 10%. When the yeast are glycolyzing anaerobically, the unidirectional Pi consumption rate was 1.0 +/- 0.2 mumol s-1 (g of wet cells)-1. At most, 80% of this is due to Pi consumption by the glycolytic enzyme glyceraldehyde-3-phosphate dehydrogenase leaving a residual activity of at least 0.2 mumol s-1 (g of wet cells)-1. Thus the activity in the oligomycin-inhibited cells under respiratory conditions and the nonglycolytic activity in anaerobic cells are equal to within the experimental errors. Furthermore the unidirectional rate of Pi consumption during anaerobic glycolysis is insensitive to oligomycin. These data suggest that the mitochondrial adenosinetriphosphatase is not turning over during anaerobic glycolysis. Possible explanations for this inhibition are discussed.
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PMID:In vivo phosphorus-31 nuclear magnetic resonance saturation transfer studies of adenosinetriphosphatase kinetics in Saccharomyces cerevisiae. 621 61

This study is designed to examine the participation of the major red cell membrane protein, band 3 protein, in the chain which transmits information from the cardiac glycoside site on the external face of the cell (Na+ + K+)-ATPase to the megadalton glycolytic enzyme complex within the cell. The experiments show that the anion transport inhibitor, 4,4'-diisothiocyano-2,2'-stilbenedisulfonic acid, affects the resonance of 2,3-diphosphoglycerate, as does the cardiac glycoside cation transport inhibitor, ouabain. Resonance shifts induced by the cardiac glycoside alone are modulated by addition of the anion transport inhibitor which indicates that there is coupling in the red cell between the (Na+ + K+)-ATPase and band 3 protein. Band 3 protein was separated from the membrane and partially purified following the technique of Yu and Steck ((1975) J. Biol. Chem. 250, 9170-9175). When glyceraldehyde-3-phosphate dehydrogenase was added to the separated band 3 protein preparation, addition of cardiac glycosides caused shifts in the 31P resonance of glyceraldehyde 3-phosphate. These experiments indicate that there is coupling between the (Na+ + K+)-ATPase and band 3 protein in the separated preparation and suggest that the anion and cation transport systems may be closely related spatially and functionally in the intact red cell.
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PMID:Relation between red cell membrane (Na+ + K+)-ATPase and band 3 protein. 627 3

Lymph-node cells of (AKR X C3H) F1 leukaemic mice showed a considerable increase of glycolytic activity and O2 consumption. The glycolytic enzymes phosphofructokinase, pyruvate kinase, aldolase and lactic acid dehydrogenase showed increased activities in leukaemic conditions. Studies on permeabilized leukaemic and normal lymph-node cells, and assays on partially purified phosphofructokinase and pyruvate kinase enzymes, revealed that the enhanced glycolysis of the tumour cells was due to the predominance of glycolytic isoenzymes relatively insensitive to the natural metabolic inhibitors. The glycolytic enzyme hexokinase showed decreased activity in leukaemic conditions, owing to a subcellular translocation of its bulk from the cytosol to the mitochondrial fraction. Association of hexokinase with the mitochondria accounted for an ATPase-like stimulatory action on cell respiration which can explain the increased O2 uptake of leukaemic cells.
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PMID:Regulation of glycolysis and oxygen consumption in lymph-node cells of normal and leukaemic mice. 645 31

Normal ankle flexion and extension was inhibited in neonatal rats by applying an adhesive cast on the day of birth such that the tibialis anterior (TA) muscle of one hindlimb was immobilized in a shortened position. Casts were changed daily for 3 weeks, at which time animals were sacrificed. Immobilized TA muscles were significantly lighter in weight, and whole muscle and teased fiber fascicular lengths were significantly shorter. No effects were seen on fiber diameter profiles, total muscle fiber number or muscle cross-sectional area. Immobilized TA muscles had significantly lower phosphofructokinase activities, and lower slow-twitch fibers than contralateral muscles. The mitochondrial enzyme succinic dehydrogenase was unaffected by the reduced activity. It is apparent that, in a developing fast-twitch muscle such as the TA, myofibrillar ATPase histochemical patterns and glycolytic enzyme activity (phosphofructokinase) may be regulated by factors dependent upon neuromuscular activity. Mitochondrial enzymes, such as succinic dehydrogenase, seem to be regulated during development by factors which are not as sensitive to activity.
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PMID:Influence of reduced neuromuscular activity on the development of neonatal rat hindlimb muscle. 645 21

Glucokinase is distinguished from yeast hexokinase and low Km mammalian hexokinases by its low affinity for glucose and its cooperative behavior, even though glucose binding residues and catalytic residues are highly conserved in all of these forms of hexokinase. The roles of Ser-151 and Asn-166 as determinants of hexose affinity and cooperative behavior of human glucokinase have been evaluated by site-directed mutagenesis, expression and purification of the wild-type and mutant enzymes, and steady-state kinetic analysis. Mutation of Asn-166 to arginine increased apparent affinity for both glucose and ATP by a factor of 3. Mutation of Ser-151 to cysteine, alanine, or glycine lowered the Km for glucose by factors of 2-, 26-, and 40-fold, respectively, decreased Vmax, abolished cooperativity for glucose, and also decreased Km for mannose and fructose. The Ser-151 mutants had hexose Km values similar to those of yeast hexokinase, hexokinase I, and the recombinantly expressed COOH-terminal half of hexokinase I. However, the Ki values for the competitive inhibitors, N-acetylglucosamine and glucose-6-P, were unchanged, suggesting that Ser-151 is not important for inhibitor binding. Mutation of Ser-151 also increased the Km for ATP about 5-fold and abolished the enzyme's low ATPase activity, which indicates it is essential for ATP hydrolysis. The substrate-induced change in intrinsic fluorescence of S151A occurred at a much lower glucose concentration than that for wild-type enzyme. The results implicate a dual role for Ser-151 as a determinant of hexose affinity and catalysis, exclusive of the glucose-induced conformational change, and suggest that the low hexose affinity of glucokinase is dependent on interaction of Ser-151 with other regions of the protein.
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PMID:Human beta-cell glucokinase. Dual role of Ser-151 in catalysis and hexose affinity. 773 Mar 77

These experiments examined the myosin phenotype and bioenergetic enzyme activities in rat respiratory muscles. Muscle samples were removed from adult female Sprague-Dawley rats (N = 8) and analyzed to determine the myosin heavy chain (MHC) and light chain (MLC) isoform content as well as the activities of myofibrillar ATPase (mATPase), citrate synthase (CS; Krebs cycle enzyme), and lactate dehydrogenase (LDH; glycolytic enzyme). Analysis revealed that CS activity and the % type I MHC and %IId MHC isoforms were greater in the costal diaphragm (CO-D) compared with those in the crural diaphragm (CR-D). In contrast, the % type IIb MHC was higher in the CR-D compared with that in the CO-D. LDH and mATPase activity were lower in both the CO-D and CR-D compared with that in the parasternal intercostals (PI), external intercostals (EI), internal intercostals (II), rectus abdominis (RA), and sternomastoid (SM) muscles. CS activity, % type I MHC, %IIa MHC, and the ratio of slow to total alkali MLC (1s/1s + 1f + 3f) were greater in the CO-D and CR-D compared with those in all other respiratory muscles. The RA contained the highest (P < 0.05) % type IIb MHC and lowest CS activity compared with that in all other muscles. Finally, CS activity, mATPase activity, and MHC phenotype did not differ among the PI, EI, II, and SM muscles. These differences in biochemical properties provide the muscles of the respiratory pump with great versatility in functional properties.
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PMID:Myosin phenotype and bioenergetic characteristics of rat respiratory muscles. 943 89

The critical minimum values of Na,K-ATPase and glycolytic enzyme activities at which the erythrocyte viability is lost were calculated using the mathematical model of the erythrocyte, which included all reactions of glycolysis, adenylate metabolism, ionic balance, and osmotic regulation of erythrocyte volume. The criterion for cell death was an increase in its volume to the level at which it is sequestrated from the circulation or is lysed. In hemolytic anemia associated with hexokinase or pyruvate kinase deficiency, activities of these enzymes measured in patient erythrocytes appeared to be close to the calculated critical values. By contrast, in hemolytic anemia associated with phosphofructokinase, glucosephosphate isomerase, triosephosphate isomerase, or phosphoglycerate kinase deficiency, activities of these enzymes measured in patient erythrocytes were significantly greater than the calculated critical values. In this case, if the deficient enzyme were stable, i.e. its activity in the cell were low, but constant in time, the deficiency observed would not account for the erythrocyte destruction observed and the development of hemolytic anemia. It was shown, however, that in phosphofructokinase, glucosephosphate isomerase, triosephosphate isomerase, or phosphoglycerate kinase deficiency, hemolytic anemia can arise because of the instability of these enzymes in time.
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PMID:Deficiencies of glycolytic enzymes as a possible cause of hemolytic anemia. 1069 93

The aim of this study was to analyze the effects of chronic administration of the beta(2)-agonist clenbuterol (1.5 mg x kg(-1) x day(-1) for 4 wk in the drinking water) on respiratory (diaphragm and parasternal intercostal) and hindlimb (tibialis and soleus) muscles in young rats during postnatal development (21 to 49 postnatal days). The treatment resulted in very little stimulation of muscle growth. Significant slow-to-fast transitions in the expression of myosin heavy chain isoforms and significant increases in the myofibrillar ATPase activity were found in the diaphragm and soleus, whereas tibialis anterior and intercostal muscles did not show any significant fiber-type alteration. Decrease of oxidative enzyme activities and increase of glycolytic enzyme activities were also observed. It is concluded that whereas the growth stimulation is age dependent and only detectable in adult rats, the fiber-type transformation is also present in weaning rats and particularly evident in the soleus and diaphragm. The fiber-type transformation caused by clenbuterol might lead to an enhancement of contractile performance and also to a reduced resistance to fatigue.
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PMID:Effects of the beta(2)-agonist clenbuterol on respiratory and limb muscles of weaning rats. 1117 67

Enolase is a dimeric glycolytic enzyme exhibiting tissue specific isoforms. During ontogenesis, a transition occurs from the embryonic alphaalpha towards the specific alphabeta, and betabeta isoforms in striated muscle. Immunocytochemical analyses on transverse sections of adult mouse gastrocnemius muscle, allowed us to compare the expression of alpha and beta subunits to that of myosin heavy chain (MHC) isoforms. Levels of beta immunoreactivity followed the order IIB > IIX > IIA > I. This gradient parallels the ATPase activity associated to MHC isoforms, indicating that the expression of beta enolase in myofibres is finely regulated as a function of energetic requirements. By contrast, variations in alpha immunolabelling intensity appeared independent of fibre types. Longitudinal muscle sections exhibited a striated pattern of alpha immunoreactivity. Confocal microscopy analyses demonstrated that alpha was localised at the M band. Most beta immunoreactivity was diffuse all over the sarcoplasm. However, some beta immunoreactivity was striated and localized at both Z and M bands. Thus, betabeta enolase could participate to multi-enzyme complexes present at the I band, and involved with local ATP production. Our results support the notion that isozymes differ in their ability to interact with other macromolecules, thus segregating to different subcellular sites where they would respond to specific functional demands.
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PMID:Fibre-type distribution and subcellular localisation of alpha and beta enolase in mouse striated muscle. 1122 3


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