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 Stoichiometry of catecholamine/proton exchange across the chromaffin-granule membrane

1980 ◽  
Vol 192 (1) ◽  
pp. 273-278 ◽  
Author(s):  
J H Phillips ◽  
D K Apps
Keyword(s):  
Transport Model ◽  
Proton Exchange ◽  
Ph Gradient ◽  
Chromaffin Granule ◽  
Amine Concentration ◽  
Low Concentrations ◽  
Granule Membrane ◽  
Chromaffin Granule Ghosts

Catecholamines are accumulated by bovine chromaffin-granule “ghosts” in the presence of MgATP at 25 degrees C. With low concentrations of catecholamine, ratios of internal to external amine concentration of up to 20 000 were obtained. These values fit well with a transport model in which amine accumulation is both electrogenic and dependent on a pH gradient across the membrane.

Reduction of Surfactant Retention in Limestones Using Sodium Hydroxide

SPE Journal ◽  
2018 ◽  
Vol 24 (01) ◽  
pp. 92-115 ◽  
Author(s):  
D.. Wang ◽  
M.. Maubert ◽  
G. A. Pope ◽  
P. J. Liyanage ◽  
S. H. Jang ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Sodium Hydroxide ◽  
Anionic Surfactants ◽  
Geochemical Modeling ◽  
Low Molecular Weight ◽  
Low Concentrations ◽  
Reservoir Conditions ◽  
Negative Surface ◽  
Negative Surface Charge ◽  
Indiana Limestone

Summary Geochemical modeling was used to design and conduct a series of alkaline/surfactant/polymer (ASP) coreflood experiments to measure the surfactant retention in limestone cores using sodium hydroxide (NaOH) as the alkali. Surfactant/polymer (SP) coreflood experiments were conducted under the same conditions for comparison. NaOH has been used for ASP floods of sandstones, but these are the first experiments to test it for ASP floods of limestones. Two studies performed under different reservoir conditions showed that NaOH significantly reduced the surfactant retention in Indiana Limestone. An ASP solution with 0.3 wt% NaOH has a pH of approximately 12.6 at 25°C. The high pH increases the negative surface charge of the carbonate, which favors lower adsorption of anionic surfactants. Another advantage of NaOH is that low concentrations of only approximately 0.3 wt% can be used because of its low molecular weight and its low consumption in limestones. Most reservoir carbonates contain gypsum or anhydrite, and therefore sodium carbonate (Na2CO3) will be consumed by the precipitation of calcium carbonate (CaCO3). As shown in the two studies, NaOH can be used in limestone reservoirs containing gypsum or anhydrite.

Low concentrations of intravenous polygelines promote low-molecular weight proteinuria

2003 ◽  
Vol 33 (11) ◽  
pp. 962-968 ◽  
Author(s):  
B. A. J. Veldman ◽  
H. L. E. Schepkens ◽  
G. Vervoort ◽  
I. Klasen ◽  
J. F. M. Wetzels
Keyword(s):  
Molecular Weight ◽  
Low Molecular Weight ◽  
Low Molecular Weight Proteinuria ◽  
Low Concentrations

The effect of a Rhizoctonia solani phytotoxin on potatoes

1976 ◽  
Vol 54 (22) ◽  
pp. 2536-2540 ◽  
Author(s):  
J. A. Frank ◽  
S. K. Francis
Keyword(s):  
Molecular Weight ◽  
Growth Hormone ◽  
Rhizoctonia Solani ◽  
Liquid Culture ◽  
Phenylacetic Acid ◽  
Low Molecular Weight ◽  
Leaf Margin ◽  
Disease Symptoms ◽  
Low Concentrations ◽  
Root Necrosis

Rhizoctonia solani produces a nonenzymatic, low-molecular-weight phytotoxin in liquid culture. Many of the disease symptoms on potato attributed to this pathogen can be induced with this toxin. These include root necrosis and stolon pruning, leaf curling, stunting, and leaf margin chlorosis. In cases of extreme susceptibility, the plants could be killed within 1 week. The toxin has similar effects on radish, beet, and corn seedlings and acts as a growth hormone in low concentrations. A technique was designed to evaluate potato clones for their resistance to the root necrosis phase of the disease syndrome. With additional purification, the toxic fraction was identified as phenylacetic acid and its metahydroxylated derivative.

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 Reduction of membrane-bound dopamine β-hydroxylase from the cytoplasmic surface of the chromaffin-granule membrane

1982 ◽  
Vol 202 (3) ◽  
pp. 759-770 ◽  
Author(s):  
M Grouselle ◽  
J H Phillips
Keyword(s):  
Accumulation Rate ◽  
Chromaffin Granule ◽  
Cytoplasmic Surface ◽  
Dopamine Beta Hydroxylase ◽  
Matrix Surface ◽  
The Matrix ◽  
Granule Membrane ◽  
Membrane Bound ◽  
Chromaffin Granule Ghosts ◽  
Low Ionic Strength

Resealed bovine chromaffin-granule ‘ghosts’ were used for assaying the membrane-bound form of dopamine beta-hydroxylase. Hydroxylation of the substrate tyramine is dependent on its accumulation within the ‘ghosts’, where the active site of the enzyme is located. Free tyramine in the medium is at a low concentration, low ionic strength and a relatively high pH (7.0), so that even in the presence of a reducing agent (co-reductant) the unaccumulated amine is hydroxylated at a negligible rate. ‘Ghosts’ contain an endogenous co-reductant, which is shown to be catecholamine remaining in the membrane itself after granule lysis. Catecholamine that is free in solution in the medium or in the interior of the ‘ghosts’ is not effective as co-reductant, nor is ascorbate, in contrast with the situation with soluble dopamine beta-hydroxylase. Ferrocyanide is an active co-reductant, however, giving a hydroxylation rate approximately equal to the tyramine accumulation rate: it does not enter the ‘ghosts’, nor does the enzyme appear to utilize ferrocyanide sealed inside the ‘ghosts’. A mechanism must therefore exist for transferring electrons across the membrane from the cytoplasmic surface to the matrix surface. NADH is not an electron donor for the enzyme, nor is cytochrome b-561 involved.

scholarly journals Hydroxytryptamine transport by the bovine chromaffin-granule membrane

1978 ◽  
Vol 170 (3) ◽  
pp. 673-679 ◽  
Author(s):  
J H Phillips
Keyword(s):  
Low Ph ◽  
Ph Gradient ◽  
Chromaffin Granule ◽  
Concentration Gradients ◽  
Granule Membrane ◽  
Chromaffin Granule Ghosts

5-Hydroxytryptamine is accumulated by resealed chromaffin-granule ‘ghosts’ if a pH gradient (acid inside) is imposed across their membranes by preincubating them at low pH. This uptake, like that driven by MgATP, is reserpine- and uncoupler-sensitive. This strongly suggests that catecholamines are taken up by intact granules in response to a pH gradient. In line with this, it is shown that 5-hydroxytryptamine decreases the pH gradient generated in the presence of MgATP, an effect that is inhibited by reserpine; nigericin, which discharges the pH gradient in the presence of K+, inhibits uptake. Permeant anions, however, also inhibit uptake. It is suggested that this may be because they permit equilibration of amine cations directly across the membrane, down concentration gradients.

scholarly journals The location of the thiol groups of myosin that are protected by pyrophosphate against reaction with 2,4-dinitrophenyl β-hydroxyethyl disulphide

1971 ◽  
Vol 125 (1) ◽  
pp. 261-266 ◽  
Author(s):  
Irena Kakol
Keyword(s):  
Atpase Activity ◽  
Binding Sites ◽  
Adenosine Triphosphatase ◽  
Thiol Groups ◽  
Low Concentrations ◽  
Light Components

Myosin modified in the presence or in the absence of pyrophosphate by 2,4-dinitrophenyl β-hydroxyethyl disulphide was treated with iodo[1-14C]acetamide. The residual Ca2+-stimulated adenosine triphosphatase (ATPase) activity of the modified myosin was different depending on the presence or absence of PPi during modification and the number of 2,4-dinitrophenyl β-hydroxyethyl disulphide-modified thiol groups. The radioactivity incorporated into the light components of myosin correlated with the Ca2+-stimulated ATPase activity of the modified myosin and decreased with decreasing residual Ca2+-stimulated ATPase activity of the modified myosin. When native myosin was treated with low concentrations of iodo[1-14C]acetamide the residual Ca2+-stimulated ATPase activity of carboxyamidomethylated myosin was high and the radioactivity incorporated into the light components of myosin was negligible. The thiol groups of the light components of myosin are essential to preserve the ATPase activity of the protein and are close to the pyrophosphate-binding sites.

HIGH CONCENTRATIONS OF HEPARIN ARE MORE INHIBITORY TO PLATE- AGGREGATION IN-VITRO THAN ARE LOW MOLECULAR WEIGHT HEPARINS AND HEPARINOIDS AT THE SAME CONCENTRATION

1987 ◽  
Author(s):  
H Messmore ◽  
B Griffin ◽  
J Seghatchian ◽  
E Coyne
Keyword(s):  
Molecular Weight ◽  
Heparan Sulfate ◽  
Dermatan Sulfate ◽  
Platelet Rich Plasma ◽  
Inhibitory Effect ◽  
Low Molecular Weight ◽  
Low Concentrations ◽  
High Concentrations ◽  
Induced Aggregation

Other investigators have shown that heparin in the usual therapeutic range (0.1-0.5 units/ml) has an enhancing effect on ADP aggregation and an inhibitory effect on collagen and thrombin induced aggregation. The effects of low molecular weight heparin (LMWH)and heparinoids (dermatan sulfate, heparan sulfate) on platelet aggregation have not been as extensivelystudied. We have utilized citrated platelet rich plasma (3.2%citrate-whole blood 1:9) drawn in plastic and adjusted to a final platelet count of 250,000/ul. A Bio-Data 4 channgl aggregometer was utilized with constantstirring at 37 C. The reaction was allowed to run for 20 minutes. Platelet rich plasma was supplemented 1:9 with saline or heparin and various agonists were then added ifno aggregation occurred. ADP, collagen, thrombin, ristocetin and serum from patients with heparin inudced thrombocytopenia (HIT) were utilized as agonists. Heparin was substituted at concentrations of 0.1 to 500 units per ml and various LMWH and heparinoids were substituted in equivalent anti-Xa or gravimetric concentrations. At low concentrations no inhibitory effect on any ofthe agonists was observed with any of the heparins or heparinoids. At concentrations of heparin of 100 u/ml or greater, all agonists were inhibited. At equivalent concentrations of five different LMWH (Cy 216, Cy 222, Pk 10169, Kabi 2165 and pentasaccharide) inhibition did notoccur at all or at very high concentions only. Dermatan sulfate and heparan sulfate inhibited only at high concentrations. HIT serum could not aggregate platelets with dermatan sulfate or pentasaccharide atany concentrations, but it was a good agonist with the other heparins and heparinoids.

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