scholarly journals Kinetics of interaction of adenosine diphosphate and adenosine triphosphate with adenosine triphosphatase of bovine heart submitochondrial particles

1980 ◽  
Vol 188 (3) ◽  
pp. 807-815 ◽  
Author(s):  
E A Vasilyeva ◽  
A F Fitin ◽  
I B Minkov ◽  
A D Vinogradov
Keyword(s):  
Atpase Activity ◽  
Rate Constant ◽  
Adenosine Diphosphate ◽  
Mitochondrial Atpase ◽  
Dependent Manner ◽  
Submitochondrial Particles ◽  
Alternative Pathways ◽  
Atpase Reaction ◽  
Inhibitory Site ◽  
Km Value

The short preincubation of submitochondrial particles with low concentrations of ADP in the presence of Mg2+ results in a complete loss of their ATPase and inosine triphosphatase activities. Other nucleoside diphosphates (IDP and GDP) do not affect the ATPase activity. The ADP-inhibited ATPase can be activated in a time-dependent manner by treatment of submitochondrial particles with the enzyme converting ADP into ATP (phosphoenolpyruvate plus pyruvate kinase). The activaton is a first-order reaction with rate constant 0.2 min-1 at 25 degrees C. The rate constant of activation is increased in the presence of ATP up to 2 min-1, and this increase shows saturation kinetics with Km value equal to that for ATPase reaction itself (10(-4) M at 25 degrees C at pH 8.0). The experimental results obtained are consistent with the model where two alternative pathways of ADP dissociation from the inhibitory site of ATPase exist; one is spontaneous dissociation and the second is ATP-dependent dissociation through the formation of the ternary complex between ADP, the enzyme and ATP. ADP-induced inactivation and ATP-dependent activation of ATPase activity of submitochondrial particles is accompanied by the same directed change of their ability to catalyse the ATP-dependent reverse electron transport from succinate to NAD+. The possible implication of the model suggested is discussed in terms of functional role of the inhibitory high-affinity binding site for ADP in the mitochondrial ATPase.

scholarly journals Mitochondrial adenosine triphosphatase of the fission yeast, Schizosaccharomyces pombe 972h-. Changes in activity and inhibitor-sensitivity in response to catabolite repression

1976 ◽  
Vol 160 (2) ◽  
pp. 335-342 ◽  
Author(s):  
D Lloyd ◽  
S W Edwards
Keyword(s):  
Atpase Activity ◽  
Schizosaccharomyces Pombe ◽  
Adenosine Triphosphatase ◽  
Specific Activity ◽  
Early Stage ◽  
Gel Filtration ◽  
Growth Cycle ◽  
Mitochondrial Atpase ◽  
Submitochondrial Particles ◽  
Fourfold Increase

1. The specific activity of mitochondrial ATPase (adenosine triphosphatase) in extracts of Schizosaccharomyces pombe decreased 2.5-fold as the glucose concentration in the growth medium decreased from 50mM to 15mM. 2. During the late exponential phase of growth, ATPase activity doubled. 3. Sensitivity to oligomycin and Dio-9 as measured by values for I50(mug of inhibitor/mg of protein giving 50% inhibition) at pH 6.8 increased sixfold and ninefold respectively during the initial decrease in ATPase activity, and this degree of sensitivity was maintained for the remainder of the growth cycle. 4. Increased sensitivity to NN′-dicyclohexylcarbodi-imide, triethyltin and venturicidin was also observed during the early stage of glucose de-repression. 5. Smaller increases in sensitivity to efrapeptin, aurovertin, 7-chloro-4-nitrobenzo-2-oxa-1,3-diaz-le, quercetin and spegazzinine also occurred. 6. The ATPase of glycerol-grown cells was less sensitive to inhibitors than that of glucose-repressed cells; change in values for I50 were not so marked during the growth cycle of cells growing with glycerol. 7. When submitochondrial particles from glycerol-grown cells were tested by passage through Sephadex G-50, a fourfold increase in activity was accompanied by increased inhibitor resistance. 8. Gel filtration of submitochondrial particles from glucose-de-repressed cells gave similar results, whereas loss of ATPase occurred in submitochondrial particles from glucose-repressed cells. 9. It is proposed that alterations in sensitivity to inhibitors at different stages of glucose derepression may be partly controlled by a naturally occuring inhibitor of ATPase. 10. The inhibitors tested may be classififed into two groups on the basis of alterations of sensitivity of the ATPase during physiological modification: (a) oligomycin, Dio-9, NN′-dicyclohexylcarbodi-imide, venturicidin and triethyltin, and (b) efrapeptin, aurovertin, 7-chloro-4-nitrobenzo-2-oxa-1,3-diazole, quercetin and spegazzinine.

scholarly journals Interaction of Mg2+ with F0.F1 mitochondrial ATPase as related to its slow active/inactive transition

1991 ◽  
Vol 276 (1) ◽  
pp. 149-156 ◽  
Author(s):  
V V Bulygin ◽  
A D Vinogradov
Keyword(s):  
Atpase Activity ◽  
Dissociation Constants ◽  
Specific Binding ◽  
Order Rate Constant ◽  
Mitochondrial Atpase ◽  
Sephadex Column ◽  
Specific Binding Sites ◽  
Mitochondrial Atp Synthase ◽  
Inhibitory Site ◽  
Activation Rates

Bovine heart submitochondrial particles incubated with a low concentration of ADP in the presence of Mg2+ and passed through a Sephadex column equilibrated with EDTA exhibit sensitivity of their initial ATPase activity to preincubation with Mg2+. By using particles thus prepared, several characteristics of a Mg(2+)-specific inhibitory site on F0.F1 ATPase were studied. The inhibition was shown to be both time- and Mg(2+)-concentration-dependent, with an equilibrium constant (at infinite time) of 2 x 10(-6) M (25 degrees C, pH 7.5). The dependence of the pseudo-first-order rate constant for the inhibition process on Mg2+ concentration suggests the presence of a single Mg(2+)-binding site with K8 = 1.1 x 10(-4) M. The data obtained are consistent with a two-step mechanism of Mg(2+)-F0.F1 interaction which results in a loss of the ATPase activity; it includes rapid pH-dependent binding of Mg2+ at the site with K8 = 1.1 x 10(-4) M, followed by a slow interconversion of the Mg(2+)-F1 complex into inactive ATPase (kin. = 0.65 min-1, kact. = 0.01 min-1). The Mg(2+)-inhibited ATPase is very slowly (t1/2 approximately 90 min) re-activated in the presence of EDTA. The rate of EDTA-induced re-activation is pH-independent and can be dramatically increased by added ATP, Pi and sulphite. The dissociation constants for free ATP and P1 (5 x 10(-7) M and 1 x 10(-3) M respectively) and the maximal activation rates were determined by measuring the hyperbolic dependencies of the EDTA-induced re-activation of Mg(2+)-de-activated ATPase on the concentrations of the accelerating ligands. Taken together, the data obtained show two functionally detectable free nucleotide-specific binding sites, one site for Pi and one Mg(2+)-specific ATPase-inhibitory site on the F0.F1 mitochondrial ATP synthase complex.

scholarly journals Mixed anhydrides of nucleotides and mesitylenecarboxylic acid as new specific inhibitors of mitochondrial adenosien triphosphatase

1979 ◽  
Vol 178 (2) ◽  
pp. 339-343 ◽  
Author(s):  
I A Kozlov ◽  
M V Shalamberidze ◽  
I Y Novikova ◽  
N I Sokolova ◽  
Z A Shabarova
Keyword(s):  
Atpase Activity ◽  
Adenosine Triphosphatase ◽  
Covalent Binding ◽  
Mitochondrial Atpase ◽  
Mixed Anhydride ◽  
Submitochondrial Particles ◽  
Nucleoside Triphosphates ◽  
Mixed Anhydrides ◽  
Nucleotide Residue ◽  
Specific Inhibitors

Mixed anhydrides of nucleoside triphosphates and mesitylenecarboxylic acid inhibit soluble mitochondrial ATPase (adenosine triphosphatase), but do not inhibit ATPase of submitochondrial particles. Inhibition of soluble mitochondrial ATPase by the mixed anhydride of epsilon-ATP and mesitylenecarboxylic acid is followed by the covalent binding of one nucleotide residue to a molecule of the protein. It is suggested that this covalent binding occurs in the catalytic site of the mitochondrial ATPase. The mixed anhydride of ADP and mesitylenecarboxylic acid inhibits the ATPase activity of submitochondrial particles and has no effect on the activity of soluble mitochondrial ATPase. After separation of the submitochondrial particles from the mixed anhydride of ADP and mesitylenecarboxylic acid, their ATPase activity is restored to its original value (half-time of reactivation 3–4 min). Incubation of submitochondrial particles or soluble mitochondrial ATPase with the mixed anhydride of ADP and mesitylenecarboxylic acid results in AMP formation.

Inhibition of muscle actomyosin ATPase activity by mitochondrial ATPase inhibitor

1977 ◽  
Vol 75 (4) ◽  
pp. 1104-1110 ◽  
Author(s):  
Shojiro Yamazaki ◽  
Hiroshi Hasebe ◽  
Haruhiko Takisawa ◽  
Yutaka Tamaura ◽  
Yuji Inada
Keyword(s):  
Atpase Activity ◽  
Mitochondrial Atpase ◽  
Atpase Inhibitor ◽  
Actomyosin Atpase

Fibrinogen binding to the integrin αIIbβ3 modulates store-mediated calcium entry in human platelets

Blood ◽  
2001 ◽  
Vol 97 (9) ◽  
pp. 2648-2656 ◽  
Author(s):  
Juan A. Rosado ◽  
Else M. Y. Meijer ◽  
Karly Hamulyak ◽  
Irena Novakova ◽  
Johan W. M. Heemskerk ◽  
...  
Keyword(s):  
Actin Cytoskeleton ◽  
Actin Polymerization ◽  
Adenosine Diphosphate ◽  
Inhibitory Effect ◽  
Human Platelets ◽  
Dependent Manner ◽  
Concentration Dependent Manner ◽  
Integrin Αiibβ3 ◽  
Fibrinogen Binding

Abstract Effects of the occupation of integrin αIIbβ3 by fibrinogen on Ca++signaling in fura-2–loaded human platelets were investigated. Adding fibrinogen to washed platelet suspensions inhibited increases in cytosolic [Ca++] concentrations ([Ca++]i) evoked by adenosine diphosphate (ADP) and thrombin in a concentration-dependent manner in the presence of external Ca++ but not in the absence of external Ca++ or in the presence of the nonselective cation channel blocker SKF96365, indicating selective inhibition of Ca++entry. Fibrinogen also inhibited store-mediated Ca++ entry (SMCE) activated after Ca++ store depletion using thapsigargin. The inhibitory effect of fibrinogen was reversed if fibrinogen binding to αIIbβ3 was blocked using RDGS or abciximab and was absent in platelets from patients homozygous for Glanzmann thrombasthenia. Fibrinogen was without effect on SMCE once activated. Activation of SMCE in platelets occurs through conformational coupling between the intracellular stores and the plasma membrane and requires remodeling of the actin cytoskeleton. Fibrinogen inhibited actin polymerization evoked by ADP or thapsigargin in control cells and in cells loaded with the Ca++ chelator dimethyl BAPTA. It also inhibited the translocation of the tyrosine kinase p60src to the cytoskeleton. These results indicate that the binding of fibrinogen to integrin αIIbβ3 inhibits the activation of SMCE in platelets by a mechanism that may involve modulation of the reorganization of the actin cytoskeleton and the cytoskeletal association of p60src. This action may be important in intrinsic negative feedback to prevent the further activation of platelets subjected to low-level stimuli in vivo.

scholarly journals The aptamer BT200 blocks von Willebrand factor and platelet function in blood of stroke patients

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Katarina D. Kovacevic ◽  
Stefan Greisenegger ◽  
Agnes Langer ◽  
Georg Gelbenegger ◽  
Nina Buchtele ◽  
...  
Keyword(s):  
Platelet Function ◽  
Von Willebrand Factor ◽  
Stroke Prevention ◽  
Adenosine Diphosphate ◽  
Target Range ◽  
Large Artery ◽  
Dependent Manner ◽  
Secondary Stroke Prevention ◽  
Von Willebrand ◽  
Willebrand Factor

AbstractThe effect of conventional anti-platelet agents is limited in secondary stroke prevention, and their effects are blunted under high shear stress in the presence of increased levels of circulating von Willebrand factor (VWF). VWF is critically involved in thrombus formation at sites of stenotic extracranial/intracranial arteries. A third generation anti-VWF aptamer (BT200) has been generated which could be useful for secondary stroke prevention. To characterize the effects of BT200 in blood of patients with large artery atherosclerosis stroke (LAA). Blood samples were obtained from 33 patients with acute stroke or transient ischemic attack to measure inhibition of VWF activity and VWF-dependent platelet function. Patients who received clopidogrel or dual antiplatelet therapy did not differ in VWF dependent platelet function tests from aspirin treated patients. Of 18 patients receiving clopidogrel with or without aspirin, only 3 had a prolonged collagen adenosine diphosphate closure time, and none of the patients had ristocetin induced aggregation in the target range. BT200 concentration-dependently reduced median VWF activity from 178 to < 3%, ristocetin induced platelet aggregation from 40U to < 10U and prolonged collagen adenosine diphosphate closure times from 93 s to > 300 s. Baseline VWF activity correlated (r = 0.86, p < 0.001) with concentrations needed to reduce VWF activity to < 20% of normal, indicating that BT200 acts in a target concentration-dependent manner. Together with a long half-life supporting once weekly administration, the safety and tolerability observed in an ongoing phase I trial, and the existence of a reversal agent, BT200 is an interesting drug candidate.

scholarly journals Mechanisms of L-Triiodothyronine-Induced Inhibition of Synaptosomal Na+-K+-ATPase Activity in Young Adult Rat Brain Cerebral Cortex

2013 ◽  
Vol 2013 ◽  
pp. 1-9 ◽  
Author(s):  
Pradip K. Sarkar ◽  
Avijit Biswas ◽  
Arun K. Ray ◽  
Joseph V. Martin
Keyword(s):  
Cerebral Cortex ◽  
Atpase Activity ◽  
Adrenergic Receptor ◽  
Receptor Activation ◽  
Mammalian Brain ◽  
Neuronal Membrane ◽  
Dependent Manner ◽  
Adrenergic Agonist ◽  
Adult Rat ◽  
Dose Dependent

The role of thyroid hormones (TH) in the normal functioning of adult mammalian brain is unclear. Our studies have identified synaptosomal Na+-K+-ATPase as a TH-responsive physiological parameter in adult rat cerebral cortex. L-triiodothyronine (T3) and L-thyroxine (T4) both inhibited Na+-K+-ATPase activity (but not Mg2+-ATPase activity) in similar dose-dependent fashions, while other metabolites of TH were less effective. Although both T3and theβ-adrenergic agonist isoproterenol inhibited Na+-K+-ATPase activity in cerebrocortical synaptosomes in similar ways, theβ-adrenergic receptor blocker propranolol did not counteract the effect of T3. Instead, propranolol further inhibited Na+-K+-ATPase activity in a dose-dependent manner, suggesting that the effect of T3on synaptosomal Na+-K+-ATPase activity was independent ofβ-adrenergic receptor activation. The effect of T3on synaptosomal Na+-K+-ATPase activity was inhibited by theα2-adrenergic agonist clonidine and by glutamate. Notably, both clonidine and glutamate activateGi-proteins of the membrane second messenger system, suggesting a potential mechanism for the inhibition of the effects of TH. In this paper, we provide support for a nongenomic mechanism of action of TH in a neuronal membrane-related energy-linked process for signal transduction in the adult condition.

scholarly journals Modulation of cardiac Na+,K+-ATPase cell surface abundance by simulated ischemia-reperfusion and ouabain preconditioning

2013 ◽  
Vol 304 (1) ◽  
pp. H94-H103 ◽  
Author(s):  
Aude Belliard ◽  
Yoann Sottejeau ◽  
Qiming Duan ◽  
Jessa L. Karabin ◽  
Sandrine V. Pierre
Keyword(s):  
Cell Surface ◽  
Atpase Activity ◽  
Ion Transport ◽  
Cell Viability ◽  
Ischemia Reperfusion ◽  
Resistant Mutant ◽  
Surface Expression ◽  
Live Cells ◽  
Mutant Form ◽  
Dependent Manner

Na+,K+-ATPase and cell survival were investigated in a cellular model of ischemia-reperfusion (I/R)-induced injury and protection by ouabain-induced preconditioning (OPC). Rat neonatal cardiac myocytes were subjected to 30 min of substrate and coverslip-induced ischemia followed by 30 min of simulated reperfusion. This significantly compromised cell viability as documented by lactate dehydrogenase release and Annexin V/propidium iodide staining. Total Na+,K+-ATPase α1- and α3-polypeptide expression remained unchanged, but cell surface biotinylation and immunostaining studies revealed that α1-cell surface abundance was significantly decreased. Na+,K+-ATPase-activity in crude homogenates and 86Rb+ transport in live cells were both significantly decreased by about 30% after I/R. OPC, induced by a 4-min exposure to 10 μM ouabain that ended 8 min before the beginning of ischemia, increased cell viability in a PKCε-dependent manner. This was comparable with the protective effect of OPC previously reported in intact heart preparations. OPC prevented I/R-induced decrease of Na+,K+-ATPase activity and surface expression. This model also revealed that Na+,K+-ATPase-mediated 86Rb+ uptake was not restored to control levels in the OPC group, suggesting that the increased viability was not conferred by an increased Na+,K+-ATPase-mediated ion transport capacity at the cell membrane. Consistent with this observation, transient expression of an internalization-resistant mutant form of Na+,K+-ATPase α1 known to have increased surface abundance without increased ion transport activity successfully reduced I/R-induced cell death. These results suggest that maintenance of Na+,K+-ATPase cell surface abundance is critical to myocyte survival after an ischemic attack and plays a role in OPC-induced protection. They further suggest that the protection conferred by increased surface expression of Na+,K+-ATPase may be independent of ion transport.

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