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)

Yeast hexokinase A(ATP:D-hexose 6-phosphotransferase) is inactivated when incubated in the presence of xylose and ATPMg, or in the presence of D-lyxose in a reaction medium in which ATPMg is being continuously regenerated (phosphoenolpyruvate and pyruvate kinase). The inactivation is due to the phorphorylation of the protein. A linear relationship was observed between the inactivation and the incorporation of 32P from [gamma-32P] ATP. All hexokinase and ATPase activity of the enzyme is lost when one phosphoryl group is incorporated per enzyme subunit (molecular weight 51,000). The phosphoryl group is covalently bound by a ester linkage with a serine residue of the protein.
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PMID:Studies on the active site of yeast hexokinase. Specific phosphorylation of a serine residue induced by D-xylose and ATPMg. 0 82

1) The rate of 2,3-bisphosphoglycerate breakdown is independent of pH value. 2) The adenine nucleotide pattern at alkaline pH values with its characteristic lowering of ATP and the accompanying accumulation of fructose-1,6-bisphosphate is caused by a relative excess of the activity of the hexokinase-phosphofructokinase system as compared wity pyruvate kinase. 3) The breakdown of adenine nucleotides proceeds via AMP mainly through phosphatase and not via AMP deaminase. 4) The constancy of the sum of nucleotides as long as glucose is present is postulated to be due to resynthesis via adenosine kinase which competes successfully with adenosine deaminase. 5) A procedure is given to calculate ATPase activity of glucose-depleted red cells. The results indicate that the ATPase activity is less at lower pH values and declines with time. An ATPase with a high Km for ATP is postulated. 6) During glucose depletion ATP production is mostly derived from the breakdown of 2,3-bisphosphoglycerate and the supply from the pentose phosphate pool both of which proceed at a constant rate. The contribution of pentose phosphate from the breakdown of adenine nucleotides amounts to 40% of the lactate formed at pH 6.8 and is about twice the lactate at pH 8.1.
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PMID:The breakdown of adenine nucleotides in glucose-depleted human red cells. 4 52

The control theory of steady states, previously presented for linear enzymatic systems (Heinrich and Rapoport, 1974) is extended to nonlinear systems. On the basis of three theorems a new procedure for the calculation of the control strength and of the control matrix is developed. The theory is applied to the extended model of glycolysis of erythrocytes, which includes also ATP-consuming processes. Also in this model the glycolytic flux is mainly controlled by the hexokinase-phosphofructokinase-system. The control strengths of the pyruvate kinase and of the enzymes of the 2.3 P2G-bypass are negligibly small. The control strength of the ATPase is negative, i.e. an activation of this enzyme leads to a decrease of the flux. For transition states of multienzyme systems definitions are given for the mean time required for the transition of the metabolites and for the "transient control" of enzymes. Enzymes with a pronounced influence on the transition time are called time-limiting enzymes. Enzymes which excert strong control on the time-dependent processes may have little influence under steady state conditions and vice versa. The transition times of ATP have been calculated for transient states of glycolysis.
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PMID:Mathematical analysis of multienzyme systems. II. Steady state and transient control. 12 16

A method to assay (Na+-K+) dependent ATPase is described. ADP produced is determined by the pyruvate kinase -- lactate deshydrogenase system. The method is adapted on an LKB 8,600 apparatus. This method is more reproducible, more sensitive and less time consuming than Baginski's procedure. The results given by the two methods have been compared. The stimulation by NH4+, inhibiting capacity and kinetic of inhibition by different cardiotonics have been determined on intestinal brush borders.
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PMID:[(Na+ -K+) dependent adenosine triphosphate of the small intestine: determination and properties in the rat]. 12 52

It has been shown that in some cases of congenital non-spherocytic haemolytic anaemia (CNSHA) with pyruvate kinase deficiency, the primary defect may be related to diminished magnesium-stimulated ATPase activity, followed by elevation of the erythrocyte ATP level. ATP as the end product of glycolysis inhibits by negative feedback control the activities of key glycolytic enzymes involved in energy production, i.e. pyruvate kinase (PK) and phosphofructokinase (PFK). Erythrocyte-deficient PK, however, is insensitive to the stimulating effect of fructose 1,6-diphosphate (FDP), which is normally a positive effector of PK. Both competing effectors, i.e. ATP and FDP, seem to show specific interaction. PK, inactive in the presence of high concentrations of ATP, seems to lose its sensitivity to FDP. This effect persists until ATP molecules are present in excess. In vitro incubation of deficient PK with ATPase resulted in increased PK activity as well as in recovery of its sensitivity to the stimulating effect of FDP. The same effects were obtained in vivo by administering magnesium levulinate intravenously to CNSHA patients with PK deficiency. This may indicate that magnesium ions stimulate deficient ATPase activity and lead to diminution of ATP as a negative effector for other regulatory enzymes.
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PMID:Enzymatic pattern of glucose metabolic pathways in pyruvate kinase-deficient erythrocytes. 12 27

The activity of the intraerythrocytary enzymes glucose-6-phosphate dehydrogenase, pyruvate kinase, glutathione reductase and ATPase was measured before and after splenectomy in 13 patients with congenital hemolytic anemia and 3 patients suffering from chronic thrombocytopenia. All patients were treated successfully, as reflected by clinical and basal hematological parameters. Glucose-6-phosphate dehydrogenase and pyruvate kinase were significantly depressed after splenectomy. It was not possible to set up prognostic criteria of splenectomy from the intraerythrocytary enzymes.
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PMID:Intra-erythrocytary enzymes before and after splenectomy. 12 29

The rates of the ATPase [EC 3.6.1.3] reaction of the H-meromyosin-F-actin-relaxing protein system were measured in 2 mM MgCl2, 50mM KC1, and 10mM Tris-HC1 at pH 7.8 and 20 degrees in the presence and absence of 0.05-0.1 mM Ca2+ ions. The concentrations of H-meromyosin (HMM) and the F-actin-relaxing protein (F-A-PR) complex were 3.4 and 3 mg/ml, respectively, and the ATPase reaction was coupled with 4 mg/ml of pyruvate kinase [EC 2.7.1.40] and 1 or 20 mM phosphoenolpyruvate to regenerate ATP. The amount of ADP bound to HMM during the ATPase reaction was determined by measuring the amount of ADP remaining in the reaction mixture. The amount of ATP bound to HMM was determined by subtracting the amount of bound ADP from the total amount of nucleotides bound to HMM, which was measured by a rapid flow-dialysis method. The following results were obtained. 1. The ATPase activity of the HMM-F-A-RP system increased linearly with increase in the amount of ATP added, and was independent of the presence of 0.05 mM Ca2+, when the amount of ATP added was less than 1 mole/mole of HMM. In the presence of 0.05 mM Ca2+, the ATPase activity reached a maximal level when 1.2-1.5 mole of ATP was added per mole of HMM, and maintained this level even at 3 moles of added ATP/mole of HMM. In the presence of 3mM EGTA, the ATPase activity decreased with increase in the amount of ATP added, from 1.5 to 3 moles of ATP/mole of HMM, and reached the level of the HMM ATPase reaction at 3 moles of added ATP/mole of HMM. Similar results were observed when the concentration of HMM was maintained at 3.4 mg/ml and the concentration of the F-A-RP complex was decreased from 3 to 1 or 0.5 mg/ml.
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PMID:The amounts of adenosine di- and triphosphates bound to H-meromyosin and the adenosinetriphosphatase activity of the H-meromyosin-F-actin-relaxing protein system in the presence and absence of calcium ions. The physiological functions of the two routes of myosin adenosinetriphosphatase in muscle contraction. 12 89

The concept that ouabain-sensitive membrane (Na+ + K+)-ATPase-generated adenosine diphosphate (ADP) preferentially serves as the substrate for the phosphoglycerate kinase (PGK) step of erythrocyte glycolysis has been reexamined. Membrane ATPase readily provides ADP for and utilizes ATP generated in the pyruvate kinase (PK) step and is ouabain sensitive. Earlier reports in the literature, which have suggested that in hemolysates the ATPase reaction facilitating the PK reaction is ouabain-insensitive, are reinterpreted: in crude hemolysates ADP generated in the "backward" PGK reaction can account for these data. We conclude that there is no convincing evidence of selective linkage of (Na+ + K+)-ATPase with the PGK reaction.
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PMID:Explanation for the apparent lack of ouabain inhibition of pyruvate production in hemolysates: the "backward" PGK reaction. 13 Jan 75

UV Difference spectra of H-meromyosin (HMM) during the steady state of the myosin-ATPase reaction [EC 3.6.1.3] were measured in 1.5 and 0.05M KC1 in the presence of 5mM MgC1(2) and 20mM Tris-HC1 at pH 8.0 and 24 degrees, using pyruvate kinase [EC 2.7.1.40] and phosphoenolpyruvate to regenerate ATP. It was found that the difference spectrum and its dependence on ATP concentration were the same in 1.5M KC1 as in 0.05M KC1. On the bases of these and other results, the nature of the intermediates of HMM ATPase in the steady-state reaction of HMM ATPase was discussed.
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PMID:Reaction intermediates of H-meromyosin-ATPase and ultraviolet difference spectrum of H-meromyosin induced by ATP. 13 5

Hereditary non-spherocytary haemolytic anaemias have their cause in enzymopathies of the pentose phosphate cycle and the glycolysis of the erythrocytes. The 11 known enzyme defects of the erythrocytary glycolysis in consequence of the reduced preparation of adenosine triphosphatase condition a deficient stability of the membrane of the erythrocytes. Therefore, the increased autohaemolysis in normal osmotic resistance is a reference to these forms of anaemia, which are particularly to be differentiated from hereditary sperocytoses. In Middle Europe the deficiency of pyruvate kinase plays the greatest part among the otherwise rarely diagnosed enzymopenic haemolytic anaemias.
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PMID:[Defects in erythrocyte glycolysis enzymes as the cause of nonspherocytic hemolytic anemia]. 13 17


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