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)

Inactivation of the membrane-bound ATPase by tight ADP binding was studied under nonenergized conditions. The energy state of the system was controlled either by omitting MgCl2, preventing ATP hydrolysis, or by addition of an uncoupler which dissipates the delta mu H+. In the absence of Mg2+, ATP prevents the inactivation of the enzyme by ADP, in a competitive manner. This effect of ATP resembles that of GDP with Mg2+ present. In the presence of nigericin, Mg2+, and ATP, inactivation occurs after a 10-15-sec interval, during which the enzyme is able to hydrolyze ATP at a relatively rapid rate. The degree of inactivation is proportional to the level of bound ADP detected. This behavior is different from that of the coupled ATPase (no uncoupler added), where inactivation is attained only upon exhaustion of the ATP by its hydrolysis, despite the finding that ADP binds tightly to the active ATPase at all stages of the reaction. Higher levels of tightly bound ADP were detected in the presence of an uncoupler. We suggest that the interval during which the enzyme becomes inactive is that required for the enzyme to generate and bind ADP, and to change from the active to the inactive conformation. These results support the mechanism suggested previously for the modulation of the ATPase by tight nucleotide binding.
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PMID:Modulation of the chloroplast ATPase by tight ADP binding. Effect of uncouplers and ATP. 621 4

The effects of flavoglaucin from Aspergillus chevalieri (Mangin) Thom et Church on mitochondrial reactions have been investigated to obtain insight into the mode of actions on biomembranes by means of isolated rat liver mitochondria. It was found that flavoglaucin exhibited a strong uncoupling effect on oxidative phosphorylation, enhanced the latent ATPase activity, and elicited a drastic swelling of mitochondria. These reactions led to the exhaustion of ATP in cells, which may be, in part, responsible for its cytotoxicity. Flavoglaucin was toxic to isolated rat hepatocytes causing a karyoklasis, but did not show genotoxicity in hepatocyte primary culture (HPC)/DNA repair test.
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PMID:The uncoupling effect of flavoglaucin, a quinol pigment from Aspergillus chevalieri (Mangin), on mitochondrial respiration. 622 60

The activation characteristics of Mg-ATP and Ca2+ on cardiac and skeletal muscle myofibril ATPase activity were studied in rats following a run to exhaustion. In addition, the effect of varying ionic strength was determined on skeletal muscle from exhausted animals. The exhausted group (E) ran at a speed of 25 m min-1 with an 8% incline. Myofibril ATPase activities for control (C) and E were determined with 1, 3 and 5 mM Mg-ATP and 1 and 10 microM Ca2+ at pH 7.0 and 30 degrees C. For control skeletal muscle, at 1 and 10 microM Ca2+, there was an increase in ATPase activity from 1 to 5 mM Mg-ATP (P less than 0.05). For E animals the myofibril ATPase activities at 10 microM Ca2+ and all Mg-ATP concentrations were similar to C (P greater than 0.05). At 1.0 microM Ca2+ and all Mg-ATP concentrations were similar to C (P greater than 0.05). At 1.0 microM Ca2+ the activities at 3 and 5 mM Mg-ATP were greater for the E animals (P less than 0.05). Increasing KCl concentrations resulted in greater inhibition for E animals. With cardiac muscle, the myofibril ATPase activities at 1.0 microM free Ca2+ were lower for E at all Mg-ATP levels (P less than 0.05). In contrast, at 10 microM Ca2+, the E group exhibited an elevated myofibril ATPase activity. The results indicate that Mg-ATP and Ca2+ activation of cardiac and skeletal muscle myofibril ATPase is altered with exhaustive exercise.
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PMID:Myofibril ATPase activity of cardiac and skeletal muscle of exhaustively exercised rats. 623 Feb 76

Na+,K+-ATPase [EC 3.6.1.3] from pig kidneys was treated with the fluorescent reagent N-(p-(2-benzimidazolyl)phenyl)maleimide (BIPM) in the presence of CKl. The resultant preparation showed 70% of the activity with only a small change in the apparent affinity for ligands of the enzyme. The addition of Na+ to the treated preparation induced a -2.1 +/- 0.1% change of the total fluorescence intensity observed in the absence of Na+. Further addition of both Mg2+ and ATP transiently increased the fluorescence to +0.5 +/- 0.1%. After the exhaustion of ATP, the fluorescence decreased to -3.1 +/- 0.1%. This cycle can be repeated by the readdition of ATP but not by ADP. Ouabain inhibits the fluorescence change. The ligands used reduced the fluorescence intensity as follows: Mg2+ + Na+ + ATP approximately K+, none, Mg2+ approximately ATP, Na+ + ATP, Na+ approximately Na+ + Mg2+, Na+ + Mg2+ + ADP approximately Na+ + ADP. The data indicate the presence of multiple conformational states of the enzyme.
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PMID:ATP dependent reversible conformational change of Na+,K+-ATPase modified with N-(p-(2-benzimidazoly)phenyl)maleimide. 625 3

The authors examined biochemically and histochemically the activity of alkaline phosphatase and adenosinetriphosphatase in lymph nodules of experimental animals, living under the conditions of continuous noise action (3 and 5 months) at a level of 95 decibels A for 3 hours daily in the morning. There were phase changes in the activity of the examined enzymes, which revealed considerable stability even after stopping the contact of the organism with noise factor. The manifested inhibition of the activity of alkaline phosphatase and partly of adenosinetriphosphatase suggested that the cells of lymph tissue revealed disturbances in the metabolic processes, which caused exhaustion of their protective function.
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PMID:[Biochemical and histochemical studies of the alkaline phosphatase and adenosine triphosphatase levels in the lymph nodes of experimental animals after noise exposure]. 645 69

The purpose of this study was to examine the effects of varying Ca2+ activated sarcoplasmic reticulum (SR) ATPase activity of fast-twitch (FT) skeletal muscle at exhaustion and during recovery. Wistar rats (200 g) were assigned to control (C), exhausted (E), and three recovery groups (R) at 5, 15, and 30 min. Following exhaustion on a motor-driven treadmill, the gastrocnemius muscles from all groups were excised and frozen. Muscle samples were assayed for ATPase activity in a Ca2+-ethyleneglycol bis (beta-aminoethyl ether)-N,N'-tetraacetic acid (EGTA) buffering system. At 1.25 microM Ca2+, a significant depression in Ca2+ activated ATPase activity occurred in the E, 5R, 15R, and 30R groups (1.61 +/- 0.17, 1.87 +/- 0.14, 1.43 +/- 0.29, and 1.62 +/- 0.1 mumol Pi . mg-1 . 10 min-1) compared with C values (2.41 +/- 0.34 mumol Pi . mg-1 . 10 min-1) (p less than or equal to 0.05). At 5.0 microM, Ca2+ activated ATPase activity remained depressed in the E, 5R, and 15R groups compared with C and 30R groups (p less than or equal to 0.05). At 0.75 microM Ca2+, there was no significant difference between groups (p greater than or equal to 0.05). The results suggest that Ca2+ activated SR ATPase activity of fatigued FT muscle may contribute to the decreased force production at exhaustion.
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PMID:Calcium activation of sarcoplasmic reticulum ATPase following strenuous activity. 646 5

Although oral contraceptives (OCs) are yet to be legalized in Japan, it is estimated that at least 500,000 women were on pills in 1975. Intrahepatic cholestasis has been associated with OC in the Western countries, but only a few cases have been reported in Japan. A case of pill-related intrahepatic cholestasis in a 25-year old housewife will be presented in terms of clinical/pathological findings, changes in plasma and bile acid levels, and the effect of phenobarbital on bile stagnation. The patient had been taking 1 pill (Anovlar)/day, 25 days a month, for 5 months, and had experienced exhaustion, nausea, and constipation after 3 months of use; body itch and jaundice symptoms after 4 months. Cholangiography showed neither enlargement of the bile duct nor obstruction of the bile duct outside the liver. The condition was diagnosed as pill-related intrahepatic cholestasis. Total bilirubin was considerably raised; serum transaminase was moderately raised. Electromicroscopy showed the enlargement of bile canaliculi, which had electron dense bile content. Hepatic cellular peroxisome significantly increased. Plasma bile acid level, which was slightly raised initially, came down to the normal range when total bilirubin was back to normal with daily administration of phenobarbital 2 mg/kg. Studies which included experiments with rats as well as clinical-pathological results mentioned above suggested that bile stagnation was caused by ethinyl estradiol. By lowering bile canaliculi Na-K ATPase activity, ethinyl estradiol decreased bile acid independent of bile flow. Phenobarbital was effective for cholestasis by increasing bile canaliculi Na-K ATPase activity.
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PMID:[Intrahepatic cholestasis caused by oral contraceptives]. 714 55

The purpose of this study was to determine the regional and myofibrillar ATPase (M-ATPase) fibre type glycogen utilization patterns in response to increased ventilation induced by pre-exhaustive (Pre-Exh) and exhaustive (Exh) durations of swimming. Twenty-eight hamsters were studied: six controls (Con), 11 Pre-Exh (swam 82 min), 11 Exh (swam to exhaustion). We examined the optical density of PAS-stained fibres from the different regions of the diaphragm as a measure of glycogen remaining after the exercise or control period. The optical densities of PAS-stained fibres in most M-ATPase fibre types and diaphragmatic regions for the Pre-Exh and Exh groups was less than those in the Con hamsters except for the optical densities of all the M-ATPase fibre types in the sternal region. The optical densities of PAS-stained fibres in different regions and M-ATPase fibre types did not differ in the Exh and Pre-Exh groups. This data indicates that significant glycogen utilization occurred in all three M-ATPase fibre types in the costal, and both the thoracic and abdominal surface of the crural diaphragm in hamsters following pre-exhaustive and exhaustive durations of swimming. Glycogen utilization was greater in type 1 fibres of the thoracic surface of the crural region than in the type 1 fibres of the sternal region of the Pre-Exh group. Further, significant utilization of glycogen did not occur in any of the three M-ATPase fibre types of the sternal region of the diaphragm following prolonged durations of swimming. It would appear that glycogen is an important substrate in the hamster diaphragm during swimming.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Regional and fibre type glycogen utilization patterns in the hamster diaphragm following swimming. 793 92

Thirty-nine moderately endurance trained males increased their normal training programme of 2.2 h week-1 with an average training intensity of 65% of maximum heart rate (HRmax) to 2.7 h week-1 and a mean intensity of 78% of HRmax. Performance tests and measurements of the total concentrations of Na,K-ATPase (3H-ouabain binding) and Ca-ATPase, fibre type distribution and fibre area were performed in biopsies from the vastus lateralis muscle before and after increased training. The 6 weeks of training elevated VO2max from 54.9 +/- 3.1 to 58.3 +/- 3.0 ml O2 min-1 kg-1 (P < 0.0001). Exercise time to exhaustion at 86% of VO2max (pre-training) increased from 35 +/- 8 to 61 +/- 17 min (P < 0.0001). The concentration of Ca-ATPase was unaffected by the intensified training (6.74 +/- 1.03 vs. 6.68 +/- 1.07 nmol g wet wt-1), but the concentration of Na,K-ATPase increased from 307 +/- 43 to 354 +/- 59 pmol g wet wt-1 (P < 0.0001). The relative distribution of FT-fibres was correlated with the concentration of Ca-ATPase (r = 0.72, P < 0.0001). The data support the view that intensive training induces an upregulation of the concentration of skeletal muscle Na,K-ATPase, but no change in the total capacity for reaccumulation of Ca2+ into the SR. There was no correlation between the concentrations of Na,K-ATPase, Ca-ATPase and indices of endurance performance.
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PMID:Effects of intensified endurance training on the concentration of Na,K-ATPase and Ca-ATPase in human skeletal muscle. 801 Jan 32

Characterization and quantification of the Hxt2 (hexose transport) protein of Saccharomyces cerevisiae indicate that it is one of a set of differentially expressed high-affinity glucose transporters. The protein product of the HXT2 gene was specifically detected by antibodies raised against a synthetic peptide encompassing the 13 carboxyl-terminal amino acids predicted by the HXT2 gene sequence. Hxt2 migrated in sodium dodecyl sulfate-polyacrylamide gel electrophoresis as a broad band or closely spaced doublet with an average M(r) of 47,000. Hxt2 cofractionated with the plasma membrane ATPase, Pma1, indicating that it is a plasma membrane protein. Hxt2 was not solubilized by high pH or urea but was solublized by detergents, which is characteristic of an integral membrane protein. Expression of the Hxt2 protein was measured under two different conditions that produce expression of high-affinity glucose transport: a medium shift from a high (2.0%) to a low (0.05%) glucose concentration (referred to below as high and low glucose) and growth from high to low glucose. Hxt2 as measured by immunoblotting increased 20-fold upon a shift from high-glucose to low-glucose medium, and the high-affinity glucose transport expressed had a strong HXT2-dependent component. Surprisingly, Hxt2 was not detectable when S. cerevisiae growing in high glucose approached glucose exhaustion, and the high-affinity glucose transport expressed under these conditions did not have an HXT2-dependent component. The role of Hxt2 in growth during aerobic batch culture in low-glucose medium was examined. An hxt2 null mutant grew and consumed glucose significantly more slowly than the wild type, and this phenotype correlated directly with appearance of the Hxt2 protein.
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PMID:Physiological characterization of putative high-affinity glucose transport protein Hxt2 of Saccharomyces cerevisiae by use of anti-synthetic peptide antibodies. 824 39


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