Distribution and effect of the weak acids 5,5-dimethyl-2,4-oxazolidinedione (DMO) and 2,4-dinitrophenol (DNP) in membrane vesicles of Micrococcus denitrificans.
Explore the source record for details and available documents.
Biological Transport↗
SEARCH · PubMed Health
Results for “2,4-Dinitrophenol”
Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.
Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.
Further evidence for a proton pump in mouse kidney phagolysosomes: effect of nigericin and 2,4-dinitrophenol on the stimulation of intralysosomal proteolysis by ATP.
Explore the source record for details and available documents.
Adenosine Triphosphate↗
Effects of Na+ depletion, theophylline and 2,4-dinitrophenol on neutral amino acid influx and cyclic adenosine 3':5'-monophosphate levels in chicken small intestine.
Explore the source record for details and available documents.
Alanine↗
Effects of pH indicators on various activities of chromatophroes of Rhodospirillum rubrum.
1. The effects of pH indicators on activities for ATP hydrolysis in the dark and ATP-Pi exchange in the dark were examined with chromatophores from Rhodospirillum rubrum. Of thirty-one pH indicators tested, eleven (metanil yellow, 2, 4-dinitrophenol, ethyl orange, bromocresol green, resazurin, neutral red, bromthymol blue, alpha-naphtholphthalein, o-cresolphthalein, phenolphthalein, and alizarin yellow G) almost completely inhibited the activities for ATP formation and ATP-Pi exchange at concentrations of 1 mM, and were studied in detail. 2. Of the eleven pH indicators, those other than alpha-naptholphthalein, o-cresolphthalein and phenolphthalein, when assayed at appropriate concentrations, inhibited ATP-Pi exchange, but not ATP hydrolysis. In ATP-Pi exchange, these eight pH indicators at the concentrations described above were competitive against Pi, and non-competitive against ATP. The remaining three kinds of pH indicators were non-competitive against either Pi or ATP, when assayed at concentrations of the dyes that inhibited both activities. 3. The amounts of pH indicators bound with chromatophores were measured. No correlation was found between the amounts of the bound dyes and the extents of their inhibition of either ATP formation or ATP-Pi exchange. 4. Ethyl orange (pKa=4.1) and 2, 4-dinitrophenol (pKa=3.9) stimulated ATP hydrolysis to the greatest extent. The latter dye was hardly bound with chromatophores. 5. The stimulatory effects of pH indicators on ATP hydrolysis were hardly affected by extraction of quinones from chromatophores. 6. Most of the pH indicators stimulated both succinate-cytochrome c2 and NADH-cytochrome c2 reductions in the dark. 7. The mechanism of uncoupling of the electron transfer system and the phosphorylation system by pH indicators and the mechanism of the coupling are discussed.
Adenosine Triphosphate↗
Triiodothyronine effects on some electrogenic properties of frog sartorius.
At 21 degrees C in vitro, 0.2 and 2.0 muM of triiodothyronine (T3) produced an increase in resting membrane potential (RMP) of Rana pipens sartorius when the pH of the external solution was 7.4. The RMP was increased by 2.0 muM T3 in the presence of 10(-4) and 10(-3) M ouabain but not in 10(-3) M of 2,4 dinitrophenol. Small increases in RMP were observed with 2.0 muM T3 in solutions with low external Na. At pH 7.1 0.2 muM T3 produced a small transient increase in RMP. Membrane resistance (Rm) was found to decline gradually during exposure to 0.2 muM at a pH of 7.4. Treatment with 2.0 muM T3 at pH 7.4 was accompanied by a transient reduction in Rm. Similar transient changes in Rm were produced by 0.2 and 2.0 muM T3 at pH of 7.1 T3 reduced membrane resistance in isotonic K2SO4 and tris-buffered Mn (20 mM) solutions indicating that T3 increases potassium permeability. Direct action potentials were studied at pH 7.1. Overshoot, amplitude and rate of rise of the action potential underwent a gradual decrease in the presence of 0.2 muM T3 while thresholds remained unchanged. Thresholds were increased during exposure to 2.0 muM T3 whereas overshoot, amplitude and rate of rise underwent transient decreases followed by a return toward control levels.
Action Potentials↗
Ribulose biophosphate carboxylase from Thiobacillus A2. Its purification and properties.
Ribulose bisphosphate carboxylase (EC 4.1.1.39) from Thiobacillus A2 has been purified to homogeneity on the basis of polyacrylamide gel electrophoresis and U.V. analysis during sedimentation velocity studies. The enzyme had an optimum pH of about 8.2 with Tris-HCl buffers. The molecular weight was about 521000 with an Srel. of 16.9. Km for RuBP was 122 muM, for total "CO2" it was 4.17 mM, and for Mg2+ 20.0 muM. The absolute requirement for a divalent cation was satisfied by Mg2+ which was replaceable to a certain extent by Mn2+. Activity was not significantly affected by SO(2-4), SO(2-3), or S(2)O(2-3) at 1.0 mM. At this concentration S(2-) caused a 27% stimulation. All mercurials tested were inhibitory. pHMB was the most potent causing about 60% inhibition at 0.04 mM. This inhibition was reversible by low concentrations of cysteine. Cyanide was also inhibitory. Its mode of inhibition with respect to RuBP was un-competitive and with a Ki of 20 muM. Lost activity could be restored partially by GSH or Cu2+. Although azide at the concentration tested had no significant effect on enzyme activity, 2, 4-dinitrophenol at 1.0 mM caused 91% inhibition. Finally, activity was also affected by energy charge.
Adenine Nucleotides↗
Proton fluxes associated with erythrocyte membrane anion exchange.
Transient extracellular pH changes accompany the exchange of chloride for sulfate across the erythrocyte membrane. The direction of the extracellular pH change during chloride efflux and sulfate influx depends on experimental conditions. When bicarbonate is present, the extracellular pH drops sharply at the outset of the anion exchange and tends to follow the partial ionic equilibrium described by Wilbrandt (W. Wilbrandt, 1942. Pfluegers Arch. 246:291). When bicarbonate is absent, however, the anion exchange causes the pH to rise, indicating that protons are cotransported with sulfate during chloride-sulfate exchange. The pH rise can be reversed by the addition of HCO(-3) (4 muM) or 2,4-dinitrophenol (90 muM). This demonstrates that the proton-sulfate cotransport can drive proton transport uphill. The stoichiometry of the transport is that one chloride exchanges for one sulfate plus one proton. These results support the titratable carrier model proposed by Gunn (Gunn, R.B. 1972, In: Oxygen Affinity of Hemoglobin and Red Cell Acid-Base Status. M. Rorth and P. Astrup, editors. p. 823. Munksgaard, Copenhagen) for erythrocyte membrane anion exchange.
Anions↗
Isolation of calcium pump system and purification of calcium ion-dependent ATPase from heart muscle.
The procedure for the isolation of the highly active fraction of sarcoplasmic reticulum from pigeon and dog hearts is described. The method is based on the partial loading of heart microsomes with calcium and oxalate ions and the precipitation of loaded vesicles in sucrose and potassium chloride concentration gradients. Preparations obtained possess high activity of Ca2+-dependent ATPase and are also able to accumulate up to 10 mumol Ca2+ per mg protein. Purification of sarcoplasmic reticulum membranes is accompanied by a decrease in concentration of cytochrome a+a3 and an increase in the content of [32P]phosphoenzyme. The basic components in "calcium-oxalate preparation" from hearts are proteins with molecular weights of about 100000 (Ca2+-dependent ATPase) and 55000 Calcium-oxalate preparation from pigeon hearts was used for subsequent purification of Ca2+-dependent ATPase. Specific activity of purified enzyme from pigeon hearts is 12-16 mumol Pi/min per mg protein. Enzyme activity of purified Ca2+-dependent ATPase is inhibited by EGTA and is not sensitive to azide, 2,4-dinitrophenol and ouabain. The data obtained demonstrate the similarity of calcium pump systems and Ca2+-dependent ATPases isolated from heart and skeletal muscles.
Adenosine Triphosphatases↗
Mechanism of uncoupling in mitochondria: uncouplers as ionophores for cycling cations and protons.
Classical uncouplers such as 2,4-dinitrophenol have been shown to be ionophores with the capability for transporting monovalent or divalent cations with equal efficiency. The conditions appropriate for the maximal expression of this ionophoric capability have been explored. Two critical factors are the polarity of the organic phase and the pH of the aqueous phase that is equilibrated with the organic phase. The demonstrated cationic ionophoric capability of uncouplers, taken in conjunction with the known ability of uncouplers to cycle protons across a membrane phase, provides the experimental basis for the thesis that uncoupling of electron flow from ATP synthesis via classical uncouplers involves the substitution of one coupled process by another. Uncoupling thus reduces to the replacement of one driven reaction (ATP synthesis) by the driven reaction (cyclical transport) mediated by the uncoupler.
Animals↗
A quantitative description of the extension and retraction of surface protrusions in spreading 3T3 mouse fibroblasts.
We suggest a method of quantitating the motile actions of surface protrusions in spreading animal cells in culture. Its basis is the determination of the percentage of freshly plated cells which produce particle-free areas around them on a gold particle-coated glass cover slip within 50 min. Studying 3T3 cells with this assay, we found that the presence of Na+, K+, Cl-, and Mg++ or Ca++ in a neutral or slightly alkaline phosphate or bicarbonate buffered solution is sufficient to support the optimal particle removal by the cells for at least 50 min. Two metabolic inhibitors, 2,4-dinitrophenol and Na-azide, inhibit the particle removal. If D-glucose is added along with the inhibitors, particle removal can be restored, whereas the addition of three glucose analogues which are generally believed to be nonmetabolizable cannot restore the activity. Serum is not required for the mechanism(s) of the motile actions of surface protrusions in spreading 3T3 cells. However, it contains components which can neutralize the inhibitory actions of bovine serum albumin and several amino acids, particularly L-cystine or L-cystein and L-methionine. Furthermore, serum codetermines which of the major surface extension, filopodia, lamellipodia, or lobopodia, is predominantly active. We found three distinct classes of extracellular conditions under which the active surface projections are predominantly either lamellipodia, (sheetlike projections), lobopodia (blebs), or filopodia (microspikes). The quantitated dependencies on temperature, pH and the inhibition by cytochalasin B or the particle removal are very similar in all three cases. Preventing the cells from anchoring themselves for 15-20 min before plating in serum-free medium seems to stimulate particle removal threefold.
Azides↗
The transport of S-adenosyl-L-methionine in isolated yeast vacuoles and spheroplasts.
1. The properties of S-adenosyl-L-methionine accumulating system for both vacuoles and spheroplasts are described. Yeast vacuoles were obtained by a modified metabolic lysis procedure from spheroplasts of Saccharomyces cerevisiae. 2. Isolated vacuoles accumulate S-adenosyl-L-methionine by means of a highly specific transport system as indicated by competition experiments with structural analogs of S-adenosyl-L-methionine. The S-adenosyl-L-methionine transport system shows saturation kinetics with an apparent Km of 68 muM in vacuoles and 11 muM in spheroplasts. 3. S-Adenosyl-L-methionine accumulation into vacuoles does not require glucose, phosphoenolpyruvic acid, ATP, ADP nor any other tri- or di-phosphorylated nucleotides. It is insensitive to azide and 2,4-dinitrophenol which strongly inhibit the glucose-dependent accumulation of S-adenosyl-L-methionine in spheroplasts. 4. The transport of S-adenosyl-L-methionine into vacuoles is optimal at pH 7.4 and is insensitive to nystatin while the uptake of S-adenosyl-L-methionine into spheroplasts is optimal at pH 5.0 and is strongly sensitive to nystatin. On this basis it has thus been possible to measure both the intracytoplasmic and the intravacuolar pool of S-adenosyl-L-methionine. 5. Our results indicate the existence of a highly specific S-adenosyl-L-methionine transport system in the vacuolar membrane which is clearly different from the one present in the plasma membrane of yeast cells.
Biological Transport, Active↗
Properties of the 3-o-methyl-D-glucose transport system in Acholeplasma laidlawii.
Transport of 3-O-methyl-D-glucose (3-O-MG) by Acholeplasma laidlawii cells was studied. The 3-O-MG transport system appeared to be constitutive in cells grown on 3-O-MG and glucose; the transport process depended on the concentration of substrate used and exhibited typical saturation kinetics, with an apparent Km of 4.6 muM. 3-O-MG was transported as a free carbohydrate and was not metabolized further in the cell. Dependence on pH and temperature and the results of efflux and "counterflow" experiments demonstrated the carrier nature of the transport system. 6-Deoxyglucose and glucose competitively inhibited 3-O-MG transport, whereas maltose inhibited in non-competitively. p-Chloromercuribenzoate, p-chloromercuribenzene sulfonate, N-ethylmaleimide, and iodoacetate inhibited transport of 3-O-MG. Cells were able to accumulate 3-O-MG against a concentration gradient. Some electron transfer inhibitors (rotenone and amytal), arsenate, dicyclohexylcarbodiimide, and proton conductors such as 2,4-dinitrophenol, carbonylcyanide, m-chlorophenylhydrazone, pentachlorophenol, and tetrachlorotrifluoromethylbenzimidazole inhibited this process.
Acholeplasma laidlawii↗
Energy-dependent incorporation of sphingolipid precursors and fatty acids in Bacteriodes melaninogenicus.
Washed cells of Bacteroides melaninogenicus are unable to incorporate the sphingolipid precursor 3-ketodihydrosphingosine (3KDS) or dihydrosphingosine into the complete sphingolipids ceramide phosphorylethanolamine (CPE) and ceramide phosphorylglycerol (CPG), whereas growing cultures are able to do so. This result suggested that an energy source was required by washed cells to initiate the incorporation of 3KDS. Investigation of a number of energy sources for B. melaninogenicus showed that glutamine was active in driving the incorporation of 3KDS. This system shows saturation kinetics. Besides glutamine, only asparagine and reduced nicotinamide adenine dinucleotide (NADH) are effective; glutamate and other compounds are inactive. The glutamine-driven system is sensitive to 2,4-dinitrophenol, azide, N,N'- dicyclohexylcarbodiimide, and carbonyl cyanide m-chlorophenylhydrazone. Asparagine plus NADH shows a synergistic effect in stimulating the incorporation of 3KDS into CPE and CPG in washed cells. However, glutamine plus NADH and glutamine plus asparagine show no such synergy. The cytochrome-free mutant of B. melaninogenicus, strain S, incorporates 3KDS in a manner similar to the parent strain when glutamine is used to drive the reaction; NADH or asparagine, however, are ineffective when used with strain S. Vitamin K-depleted cells of B. melaninogenicus are similar to vitamin K-grown cells, when glutamine or NADH is used to drive the 3KDS incorporation. Glutamine and NADH are also effective in stimulating the incorporation of palmitate and acetate by washed cells of B, melaninogenicus. Increased incorporation of these fatty acids into CPE, CPG, 3KDS, and other phospholipids is significantly increased by the presence of glutamine or NADH. Thus, energization of the membrane of B. melaninogenicus by glutamine or the electron transport system by NADH or asparagine is required for sphingolipid and other phospholipid synthesis. The relationship of this energization to possible transport of sphingolipid precursors is discussed.
Acetates↗
Characterization studies on the membrane-bound adenosine triphosphatase (ATPase) of Azotobacter vinelandii.
The adenosinetriphosphatase (ATPase) (EC 3.6.1.3) activity in Azotobacter vinelandii concentrates in the membranous R3 fraction that is directly associated with Azotobacter electron transport function. Sonically disrupted Azotobacter cells were examined for distribution of ATPase activity and the highest specific activity (and activity units) was consistently found in the particulate R3 membranous fraction which sediments on ultracentrifugation at 144 000 X g for 2 h. When the sonication time interval was increased, the membrane-bound ATPase activity could neither be solubilized nor released into the supernatant fraction. Optimal ATPase activty occurred at pH 8.0; Mg2+ ion when added to the assay was stimulatory. Maximal activity always occurred when the Mg2+:ATP stoichiometry was 1:1 on a molar ratio at the 5 mM concentration level. Sodium and potassium ions had no stimulatory effect. The reaction kinetics were linear for the time intervals studied (0-60 min). The membrane-bound ATPase in the R3 fraction was stimulated 12-fold by treatment wiTH TRypsin, and fractionation studies showed that trypsin treatment did not solubilize ATPase activity off the membranous R3 electron transport fraction. The ATPase was not cold labile and the temperature during the preparation of the R3 fraction had no effect on activity; overnight refrigeration at 4 degrees C, however, resulted in a 25% loss of activity as compared with a 14% loss when the R3 fraction was stored overnight at 25 degrees C. A marked inactivation (although variable, usually about 60%) did occur by overnight freezing (-20 degrees C), and subsequent sonication failed to restore ATPase activity. This indicates that membrane reaggregation (by freezing) was not responsible for ATPase inactivation. The addition of azide, ouabain, 2,4-dinitrophenol, or oligomycin to the assay system resulted in neither inhibition nor stimulation of the ATPase activity. The property of trypsin activation and that ATPase activity is highest in the R3 electron transport fraction suggests that its probable functional role is in coupling of electron transport to oxidative phosphorylation.
Adenosine Triphosphatases↗
Respiratory effects of H+ and dinitrophenol injections into the brain stem subarachnoid space of fetal lambs.
Mock cerebrospinal fluid (pH 5.37-8.38) or 2,4-dinitrophenol (DNP) (0.15-1.5 mg) was injected into the subarachnoid space of the ventral brain stem of exteriorized fetal sheep. Changes in pH on the ventral surface of the medulla did not stimulate respiratory efforts or induce significant cardiovascular changes. The respiratory response to DNP injections ranged from no response to prolonged rhythmic ventilation that was independent of the peripheral chemoreceptors or the control arterial pH and blood gas tensions. This inconsistency suggests an effector site somewhat removed from the immediate surface of the medulla. The heart rate and blood pressure were not affected. It is concluded that increased H+ concentration in the extracellular fluid of the fetal ventral medulla does not initiate respiration, and any respiratory response to metabolic inhibitors applied to this area therefore is not attributable to a secondary change in surface pH.
Animals↗
Afferent neural pathway in the regulation of cardiopulmonary responses to tissue hypermetabolism.
We studied the role of neural transmission from hypermetabolic peripheral tissues in the regulation of cardiac output and pulmonary ventilation in chloralose-anesthetized dogs. Cross-circulation techniques with femoral-femoral or femoral-aortic anastomoses were used to produce a vascularly isolated, but normally innervated, hindlimb or lower half-body, 2,4-Dinitrophenol (DNP) was infused into the arterial side of the perfusion circuit to triple oxygen consumption and to increase lactate production by the cross-perfused area. After infusion of DNP, cardiac output and mean systemic arterial blood pressure increased, but neither heart rate nor pulmonary artery wedge pressure changed significantly. Pulmonary minute ventilation and arterial pH also increased, while arterial PCO2 fell. These changes were abolished when the nerve connections between the perfused limb and its parent body were severed. Normal saline, when administered in a similar manner, did not increase either ventilation or cardiac output, and simple denervation without previous infusions of DNP also had no effect. These results indicate that there are receptors sensitive to metabolic changes in the tissue, and that neural transmission is an important afferent link in regulating the cardiopulmonary responses to increased tissue metabolism.
Afferent Pathways↗
Reversible binding of Pi by beef heart mitochondrial adenosine triphosphatase.
Beef heart mitochondrial ATPase (F1) exhibited a single binding site for Pi. The interaction with Pi was reversible, partially dependent on the presence of divalent metal ions, and characterized by a dissociation constant at pH 7.5 of 80 micronM. A variety of substances known to influence oxidative phosphorylation or the activity of the soluble ATPase (F1) also influenced Pi binding by the enzyme. Thus aurovertin, an inhibitor of oxidative phosphorylation, which was bound tightly by F1 and inhibited ATPase activity, enhanced Pi binding via a 4-fold increase in the affinity of the enzyme for Pi (KD = 20 micronM) but did not alter binding stoichiometry. Anions such as SO4(2-), SO3(2-), chromate, and 2,4-dinitrophenolate, which stimulated ATPase activity of F1, also enhanced Pi binding. Inhibitors of ATPase activity such as nickel/bathophenanthroline and the protein ATPase inhibitor of Pullman and Monroy (Pullman, M. E., and Monroy, G. C. (1963) J. Biol. Chem. 238, 3762-3769) inhibited Pi binding. The adenine nucleotides ADP, ATP, and the ATP analog adenylyl imidodiphosphate as well as the Pi analog arsenate, also inhibited Pi binding. The observations suggest that the Pi binding site was located in or near an adenine nucleotide binding site on the molecule.
Adenine Nucleotides↗
Factors which influence blood platelet migration.
Migration of human blood platelets in vitro was investigated by a modification of the capillary-tube migration chamber technique used to study the migration inhibition factor of macrophages. Platelets were packed in capillary tubes and incubated in autologous platelet-free plasma (PFP). The extent of migration was quantified by planimetry (measurement of the area of platelet migration visible by stereomicroscopy). Among the various anticoagulants employed, sodium citrate was most suitable for studying platelet migration. Optimal migration occured at 22 degrees to 37 degrees C and pH 7.2 to 7.4. Migration was inhibited by metabolic inhibitors such as iodoacetic acid, sodium fluoride, and 2,4-dinitrophenol, and inhibition was proportional to the dose of the agent added to the incubation medium. Mobility was also inhibited by cytochalasin B, which disrupts cellular microfilaments, at 1 microgram/ml PFP, but not by colchicine, a microtubule inhibitor, even at 40 microgram/ml of PFP. Light and electron microscopy showed that this inhibition was not ascribable to platelet clumping. These observations suggest that platelet mobility is an active process. The possible significance of platelet migration in hemostasis is discussed.
Anticoagulants↗