scholarly journals Isolation of ATPase I, the proton pump of chromaffin-granule membranes

1985 ◽  
Vol 231 (3) ◽  
pp. 557-564 ◽  
Author(s):  
J M Percy ◽  
J G Pryde ◽  
D K Apps
Keyword(s):  
Proton Pump ◽  
Alkylating Agents ◽  
Proton Translocation ◽  
Phase Segregation ◽  
Chromaffin Granule ◽  
Chromaffin Granule Ghosts ◽  
Triton X ◽  
Atpase Ii ◽  
Hydrolysis Of ◽  
Granule Matrix

Chromaffin-granule membranes contain two ATPases, which can be separated by (NH4)2SO4 fractionation after solubilization with detergents, or by phase segregation in Triton X-114. ATPase I (Mr 400000) is inhibited by trialkyltin, quercetin and alkylating agents, and hydrolyses both ATP and ITP. It contains up to five types of subunit, including a low-Mr hydrophobic polypeptide that reacts with dicyclohexylcarbodi-imide; these subunits are unrelated to those of mitochondrial F1F0-ATPase, as judged by size and reaction with antibodies. ATPase II (Mr 140000) is inhibited by vanadate, and is specific for ATP; it has not been extensively purified. Proton translocation by resealed chromaffin-granule ‘ghosts’, measured by uptake of methylamine or by quenching of the fluorescence of 9-amino-6-chloro-2-methoxyacridine, is supported by the hydrolysis of ATP or ITP, and inhibited by quercetin or alkylating agents, but not by vanadate. ATPase I must therefore be the proton translocator involved in the uptake of catecholamines and possibly of other components of the chromaffin-granule matrix, whereas ATPase II does not translocate protons.

scholarly journals Inhibition of adenosine triphosphatase, 5-hydroxytryptamine transport and proton-translocation activities of resealed chromaffin-granule ‘ghosts’

1980 ◽  
Vol 190 (2) ◽  
pp. 273-282 ◽  
Author(s):  
David K. Apps ◽  
James G. Pryde ◽  
Raul Sutton ◽  
John H. Phillips
Keyword(s):  
Molecular Weight ◽  
Atpase Activity ◽  
Adenosine Triphosphatase ◽  
Proton Translocation ◽  
Low Molecular Weight ◽  
Chromaffin Granule ◽  
Low Concentrations ◽  
Tributyltin Chloride ◽  
Granule Membrane ◽  
Chromaffin Granule Ghosts

1. Highly purified resealed chromaffin-granule ‘ghosts’ were assayed for ATPase and ATP-driven H+-translocation and 5-hydroxytryptamine-uptake activities, and for 5-hydroxytryptamine uptake driven by an imposed transmembrane H+-gradient. The effects of several inhibitors on these activities were studied. 2. Dicyclohexylcarbodi-imide inhibits all of these activities, but not in parallel; at low concentrations it decreases the permeability of the membrane to protons. 3. 4-Chloro-7-nitrobenzofuran (Nbf-Cl) and silicotungstate inhibit ATP-dependent activities, without effect on 5-hydroxytryptamine uptake driven by an imposed H+-gradient. 4. Tributyltin chloride inhibits all of the activities. 5. Treatment of the ‘ghosts’ with low concentrations of urea inhibits 5-hydroxytryptamine uptake and ATP-dependent generation of a transmembrane H+-gradient, without inhibiting ATPase activity. 6. Nbf-Cl and silicotungstate are without effect on the rate of leakage of 5-hydroxytryptamine from preloaded ‘ghosts’, whereas dicyclohexylcarbodi-imide and tributyltin chloride accelerate the rate of leakage. 7. Treatment of the membranes with 14C-labelled Nbf-Cl labels several proteins; membranes treated with dicyclohexyl[14C]carbodi-imide are labelled predominantly in a protein of low molecular weight, which may be analogous to the mitochondrial H+-conducting proteolipid. 8. It is concluded that Nbf-Cl and silicotungstate inhibit the H+-translocating ATPase of the granule membrane; that dicyclohexylcarbodi-imide inhibits the ATPase, and inhibits 5-hydroxytryptamine accumulation by accelerating leakage of the amine; and that the effects of tributyltin chloride are due to inhibition of the ATPase, and collapse of the transmembrane H+-gradient through OH−-anion exchange.

scholarly journals ATP-dependent proton translocation in resealed chromaffin granule ghosts

FEBS Letters ◽  
1977 ◽  
Vol 78 (1) ◽  
pp. 53-56 ◽  
Author(s):  
Torgeir Flatmark ◽  
Ole Chr. Ingebretsen
Keyword(s):  
Proton Translocation ◽  
Chromaffin Granule ◽  
Chromaffin Granule Ghosts

Clinical Impact of Co-medication of Levetiracetam and Clobazam with Proton Pump Inhibitors: A Drug Interaction Study

2020 ◽  
Vol 21 (2) ◽  
pp. 126-131
Author(s):  
Bhuvanachandra Pasupuleti ◽  
Vamshikrishna Gone ◽  
Ravali Baddam ◽  
Raj Kumar Venisetty ◽  
Om Prakash Prasad
Keyword(s):  
Plasma Concentration ◽  
Proton Pump Inhibitors ◽  
Proton Pump ◽  
Plasma Concentrations ◽  
Control Group ◽  
Drug Concentrations ◽  
Significant Difference ◽  
Post Hoc ◽  
Hydrolysis Of ◽  
Cytochrome P 450

Background: Clobazam (CLBZ) metabolized primarily by Cytochrome P-450 isoenzyme CYP3A4 than with CYP2C19, Whereas Levetiracetam (LEV) is metabolized by hydrolysis of the acetamide group. Few CYP enzymes are inhibited by Proton Pump Inhibitors (PPIs) Pantoprazole, Esomeprazole, and Rabeprazole in different extents that could affect drug concentrations in blood. The aim of the present study was to evaluate the effect of these PPIs on the plasma concentrations of LEV and CLBZ. Methods: Blood samples from 542 patients were included out of which 343 were male and 199 were female patients and were categorized as control and test. Plasma samples analyzed using an HPLC-UV method. Plasma concentrations were measured and compared to those treated and those not treated with PPIs. One way ANOVA and games Howell post hoc test used by SPSS 20 software. Results: CLBZ concentrations were significantly 10 folds higher in patients treated with Pantoprazole (P=0.000) and 07 folds higher in patients treated with Esmoprazole and Rabeprazole (P=0.00). Whereas plasma concentration of LEV control group has no statistical and significant difference when compared to pantoprazole (P=0.546) and with rabeprazole and esomeprazole was P=0.999. Conclusion: The effect of comedication with PPIs on the plasma concentration of clobazam is more pronounced for pantoprazole to a greater extent when compared to esomeprazole and rabeprazole. When pantoprazole is used in combination with clobazam, dose reduction of clobazam should be considered, or significance of PPIs is seen to avoid adverse effects.

scholarly journals The roles of phospholipase D and a GTP-binding protein in guanosine 5′-[γ-thio]triphosphate-stimulated hydrolysis of phosphatidylcholine in rat liver plasma membranes

1990 ◽  
Vol 272 (3) ◽  
pp. 749-753 ◽  
Author(s):  
K M Hurst ◽  
B P Hughes ◽  
G J Barritt
Keyword(s):  
Rat Liver ◽  
Phospholipase D ◽  
Plasma Membranes ◽  
Regulatory Protein ◽  
Gtp Binding ◽  
Liver Plasma Membranes ◽  
Low Concentrations ◽  
Rat Liver Plasma Membranes ◽  
Triton X ◽  
Hydrolysis Of

1. Guanosine 5′-[gamma-thio]triphosphate (GTP[S]) stimulated by 50% the rate of release of [3H]choline and [3H]phosphorylcholine in rat liver plasma membranes labelled with [3H]choline. About 70% of the radioactivity released in the presence of GTP[S] was [3H]choline and 30% was [3H]phosphorylcholine. 2. The hydrolysis of phosphorylcholine to choline and the conversion of choline to phosphorylcholine did not contribute to the formation of [3H]choline and [3H]phosphorylcholine respectively. 3. The release of [3H]choline from membranes was inhibited by low concentrations of SDS or Triton X-100. Considerably higher concentrations of the detergents were required to inhibit the release of [3H]phosphorylcholine. 4. Guanosine 5′-[beta gamma-imido]triphosphate and guanosine 5′-[alpha beta-methylene]triphosphate, but not adenosine 5′-[gamma-thio]-triphosphate, stimulated [3H]choline release to the same extent as did GTP[S]. The GTP[S]-stimulated [3H]choline release was inhibited by guanosine 5′-[beta-thio]diphosphate, GDP and GTP but not by GMP. 5. It is concluded that, in rat liver plasma membranes, (a) GTP[S]-stimulated hydrolysis of phosphatidylcholine is catalysed predominantly by phospholipase D with some contribution from phospholipase C, and (b) the stimulation of phosphatidylcholine hydrolysis by GTP[s] occurs via a GTP-binding regulatory protein.

scholarly journals Characterization of ATP Transport into Chromaffin Granule Ghosts

1996 ◽  
Vol 271 (29) ◽  
pp. 17132-17138 ◽  
Author(s):  
Laurie A. Bankston ◽  
Guido Guidotti
Keyword(s):  
Chromaffin Granule ◽  
Chromaffin Granule Ghosts
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