scholarly journals Spermine binding to submitochondrial particles and activation of adenosine triphosphatase

1984 ◽  
Vol 218 (2) ◽  
pp. 495-499 ◽  
Author(s):  
G Solaini ◽  
B Tadolini
Keyword(s):  
Atpase Activity ◽  
Coupling Factor ◽  
Hill Coefficient ◽  
Atpase Inhibitor ◽  
Binding Studies ◽  
Submitochondrial Particles ◽  
Physiological Concentration ◽  
F1 Atpase ◽  
Atpase Assay ◽  
Hill Plots

Studies on the effects of polyamines on oligomycin-sensitive ATPase activity of ox heart submitochondrial particles showed that, of the polyamines tested, only spermine affected the enzyme activity. Spermine within the physiological concentration range increased the Vmax. of the enzyme, but the Km for ATP was virtually unaffected. Binding studies of [14C]spermine to submitochondrial particles, under the same conditions as used for the ATPase assay, showed that the spermine binds to submitochondrial particles in a co-operative way; Hill plots of the data gave a Hill coefficient of 2 and a Kd of 8 microM. When submitochondrial particles were treated with trypsin, ATPase was not stimulated by spermine and the amount of spermine bound concomitantly was drastically decreased. The ATPase activity of isolated F1-ATPase was not affected by spermine. Removal of the natural protein ATPase inhibitor did not suppress either the stimulation of the ATPase activity by spermine or the spermine binding to the particles. The results obtained suggested that the polyamine binds and acts at the level of the liaison between the coupling factor F1 and the membrane sector F0 of the ATPase complex.

scholarly journals The adenosine triphosphatase-inhibitor content of bovine heart submitochondrial particles. Influence of the inhibitor on adenosine triphosphate-dependent reactions

1977 ◽  
Vol 162 (2) ◽  
pp. 351-357 ◽  
Author(s):  
S J Ferguson ◽  
D A Harris ◽  
G K Radda
Keyword(s):  
Atpase Activity ◽  
Adenosine Triphosphatase ◽  
Type I ◽  
Type Ii ◽  
Inhibitor Protein ◽  
Isolation Method ◽  
Atpase Inhibitor ◽  
Submitochondrial Particles ◽  
Bovine Heart ◽  
Tightly Bound Nucleotides

1. The activity of the ATPase (adenosine triphosphatase) of phosphorylating particles prepared by sonication of bovine heart mitochondria in the presence of MgCl2 and ATP is influenced by the isolation method for the mitochondria used in the preparation of particles. Type-I particles, made from mitochondria isolated in a medium lacking succinate, have a lower ATPase activity than to Type-II particles, which are prepared from mitochondria isolated in a medium containing succinate. 2. Centrifugation under appropriate energized conditions increases the ATPase activity of Type-I particles almost to that of the Type-II particles. The ATPase activity of Type-II particles was only slightly stimulated by this procedure. These data are interpreted as indicating a higher content of the ATPase-inhibitor protein in the Type-I particles. 3. A comparison was made of the ATP-driven enhancement of 8-anilinonaphthalene-1-sulphonate fluorescence and the exchange of the endogenous tightly bound nucleotides of the ATPase in Type-I and Type-II particles. The effect of exogenous inhibitor protein on both these reactions was also studied. 4. The time-scale on which the inhibitor protein can exchange between ATPase molecules is discussed.

scholarly journals Isolation of α-subunits of factor F1 from submitochondrial particles and the reconstitution of active ATPase from isolated α-subunits and β-subunits bound to the mitochondrial membrane

1980 ◽  
Vol 192 (2) ◽  
pp. 483-488 ◽  
Author(s):  
I A Kozlov ◽  
Y M Milgrom ◽  
I S Tsybovski
Keyword(s):  
Atpase Activity ◽  
Active Site ◽  
Mitochondrial Membrane ◽  
Iodoacetic Acid ◽  
Reduced Form ◽  
Beta Subunits ◽  
Submitochondrial Particles ◽  
F1 Atpase ◽  
Alpha Subunits ◽  
Α Subunits

The alpha-subunits of factor-F1 ATPase are removed by extraction of submitochondrial particles with 1.75 M-LiCl, with the consequent loss of ATPase activity. ATPase activity is reconstituted by incubation of LiCl-extracted particles with purified alpha-subunits, and the reconstituted ATPase activity is oligomycin-sensitive. Reconstitution is enhanced by maintenance of the alpha-subunits in reduced form by dithiothreitol or NaBH4 and by modification of the alpha-subunits by p-chloromercuribenzoate, iodoacetic acid or N-ethylmaleimide. Experiments with the mixed anhydride of ATP and mesitylene-carboxylic acid, which was previously shown to interact with the F1 active site, localized on the beta-subunits, indicate that the active site of ATPase is shielded by the alpha-subunits.

Mitochondrial F1-ATPase activity of canine myocardium: effects of hypoxia and stimulation

1994 ◽  
Vol 266 (6) ◽  
pp. H2396-H2403 ◽  
Author(s):  
T. D. Scholz ◽  
R. S. Balaban
Keyword(s):  
Oxidative Phosphorylation ◽  
Atpase Activity ◽  
Citrate Synthase ◽  
Submitochondrial Particles ◽  
F1 Atpase ◽  
Baseline Levels ◽  
Ph Buffer ◽  
Phenylephrine Infusion ◽  
Intact Heart ◽  
Canine Myocardium

Recent studies have suggested that modifications in mitochondrial F1-adenosinetriphosphatase (ATPase) activity may play an important role in the regulation of myocardial oxidative phosphorylation. The goal of the present study was to develop and characterize an assay of F1-ATPase activity that could be performed repeatedly on an intact heart under various physiological states. With the use of submitochondrial particles prepared from biopsy samples of canine myocardium, we found reproducible F1-ATPase activity when normalized to the activity of the intramitochondrial enzyme citrate synthase. The oligomycin-sensitive component of the ATPase activity was found to be mainly F1-ATPase. F1-ATPase activity of normal myocardium increased by incubation in high salt-pH buffer, suggesting baseline inhibition. Five minutes after global ischemia, F1-ATPase activity decreased to 60% of baseline. Hypoxia for 10 min resulted in no significant change in F1-ATPase activity. With phenylephrine infusion, myocardial oxygen consumption more than doubled, whereas F1-ATPase activity increased by approximately 30%. Both returned to baseline levels after discontinuation of the drug. With the use of an assay developed to measure F1-ATPase activity of intact myocardium, changes of the enzyme activity were found during both ischemia and at increased work loads. These data suggest that alterations of F1-ATPase activity may contribute to the regulation of myocardial oxidative phosphorylation.

Phosphate Binding to Isolated Chloroplast Coupling Factor (CF1)

1988 ◽  
Vol 43 (3-4) ◽  
pp. 213-218 ◽  
Author(s):  
Bernhard Huchzermeyer
Keyword(s):  
Atpase Activity ◽  
Binding Site ◽  
Inorganic Phosphate ◽  
Coupling Factor ◽  
Binding Domain ◽  
Atp Binding ◽  
Phosphate Binding ◽  
Chloroplast Coupling Factor ◽  
Single Binding Site ◽  
Site Binding

A single binding site for phosphate was found on isolated chloroplast coupling factor in the absence of nucleotides. In our experiments the phosphate binding site showed a Kd of 170 μᴍ. We did not observe any differences whether the ATPase activity of CF] had been activated or not. If the enzyme was incubated with [γ-32P]ATP the amount of 32P bound per CF1 depended on the pretreatment of the enzyme: In the presence of ADP no ATP or phosphate was bound to CF,. After activation of ATPase activity one mol of ATP per mol CF, was rapidly bound and hydrolyzed while there was a slowly occurring binding of another phosphate without concomitant nucleotide binding. We conclude that there are two different types of phosphate binding observed in our experiments: 1) Inorganic phosphate can be bound by one catalytic site per mol of CF1 2) The γ-phosphate of ATP is able to bind to an ATP binding domain of the enzyme if this domain can exchange substrates with the incubation medium. This ATP binding domain appears to differ from the site binding inorganic phosphate, because at least a portion of the coupling factor contains more than one labelled phosphate during our ATPase tests.

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

Effects of bafilomycin A1 on cytosolic pH of sheep alveolar and peritoneal macrophages: evaluation of the pH-regulatory role of plasma membrane V-ATPases.

1995 ◽  
Vol 198 (8) ◽  
pp. 1711-1715 ◽  
Author(s):  
T A Heming ◽  
D L Traber ◽  
F Hinder ◽  
A Bidani
Keyword(s):  
Plasma Membrane ◽  
Atpase Activity ◽  
Initial Rate ◽  
Cell Types ◽  
Peritoneal Macrophages ◽  
Bafilomycin A1 ◽  
Atpase Inhibitor ◽  
Cytosolic Ph ◽  
Phi Regulation

The role of plasma membrane V-ATPase activity in the regulation of cytosolic pH (pHi) was determined for resident alveolar and peritoneal macrophages (m theta) from sheep. Cytosolic pH was measured using 2',7'-biscarboxyethyl-5,6-carboxyfluorescein (BCECF). The baseline pHi of both cell types was sensitive to the specific V-ATPase inhibitor bafilomycin A1. Bafilomycin A1 caused a significant (approximately 0.2 pH units) and rapid (within seconds) decline in baseline pHi. Further, bafilomycin A1 slowed the initial rate of pHi recovery (dpHi/dt) from intracellular acid loads. Amiloride had no effects on baseline pHi, but reduced dpHi/dt (acid-loaded pHi nadir < 6.8) by approximately 35%. Recovery of pHi was abolished by co-treatment of m theta with bafilomycin A1 and amiloride. These data indicate that plasma membrane V-ATPase activity is a major determinant of pHi regulation in resident alveolar and peritoneal m theta from sheep. Sheep m theta also appear to possess a Na+/H+ exchanger. However, Na+/H+ exchange either is inactive or can be effectively masked by V-ATPase-mediated H+ extrusion at physiological pHi values.

scholarly journals Short-term K+ deprivation provokes insulin resistance of cellular K+ uptake revealed with the K+ clamp

2001 ◽  
Vol 280 (1) ◽  
pp. F95-F102 ◽  
Author(s):  
Cheol S. Choi ◽  
Curtis B. Thompson ◽  
Patrick K. K. Leong ◽  
Alicia A. McDonough ◽  
Jang H. Youn
Keyword(s):  
Insulin Resistance ◽  
Atpase Activity ◽  
Infusion Rate ◽  
Insulin Action ◽  
Insulin Dose ◽  
Short Term ◽  
Conscious Rat ◽  
Physiological Concentration ◽  
Glucose Clearance

We aimed to test the feasibility of quantifying insulin action on cellular K+ uptake in vivo in the conscious rat by measuring the exogenous K+ infusion rate needed to maintain constant plasma K+ concentration ([K+]) during insulin infusion. In this “K+ clamp” the K+ infusion rate required to clamp plasma [K+] is a measure of insulin action to increase net plasma K+ disappearance. K+ infusion rate required to clamp plasma [K+] was insulin dose dependent. Renal K+ excretion was not significantly affected by insulin at a physiological concentration (∼90 μU/ml, P > 0.05), indicating that most of insulin-mediated plasma K+ disappearance was due to K+ uptake by extrarenal tissues. In rats deprived of K+ for 2 days, plasma [K+] fell from 4.2 to 3.8 mM, insulin-mediated plasma glucose clearance was normal, but insulin-mediated plasma K+ disappearance decreased to 20% of control, even though there was no change in muscle Na-K-ATPase activity or expression, which is believed to be the main K+ uptake route. After 10 days K+ deprivation, plasma [K+] fell to 2.9 mM, insulin-mediated K+ disappearance decreased to 6% of control (glucose clearance normal), and there were 50% decreases in Na-K-ATPase activity and α2-subunit levels. In conclusion, the present study proves the feasibility of the K+ clamp technique and demonstrates that short-term K+ deprivation leads to a near complete insulin resistance of cellular K+uptake that precedes changes in muscle sodium pump expression.

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