Studies on the Mechanism of NAD-photoreduction by Chromatophores of the Facultative Phototroph, Rhodopseudomonas capsulata

1969 ◽  
Vol 24 (1) ◽  
pp. 67-76 ◽  
Author(s):  
J.-H. Klemme
Keyword(s):  
Nicotinamide Adenine Dinucleotide ◽  
Molecular Hydrogen ◽  
Reaction System ◽  
Electron Donors ◽  
Rhodopseudomonas Capsulata ◽  
Antimycin A ◽  
Inhibitory Effects ◽  
Carbonyl Cyanide ◽  
Cyclic Photophosphorylation ◽  
Energy Dependent

The light-driven and the ATP-driven reduction of nicotinamide adenine dinucleotide (NAD) catalyzed by the chromatophore fraction of Rhodopseudomonas capsulata was investigated. Efficient electron donors for the photoreduction of NAD are molecular hydrogen and succinate. In the ATP-dependent reaction system, succinate is a more efficient electron donor than H2. The energydependent NAD-reduction is driven by ATP, but not by pyrophosphate or ADP. Oligomycin stimulates the NAD-photoreductions and completely inhibits the ATP-driven NAD-reductions. Rotenone and piericidin A are inhibitors for both the light-driven and the ATP-driven NAD-reductions. Antimycin A is an inhibitor only for the light-driven reductions. The H2-linked NAD-photoreduction is less sensitive to these inhibitors and to the uncoupler desaspidin than the succinate-linked reduction. Atebrine, carbonyl cyanide-m-chlorophenylhydrazone, 2,4-dinitrophenol and phenazonium methosulfate are inhibitors for the light-driven and the ATP-driven reductions. Some of the compounds used as inhibitors of the NAD-reduction were also investigated with concerns to their inhibitory effects on cyclic photophosphorylation and O2-linked oxidations of reduced NAD, succinate and H2. Based on the results of these inhibitor studies, the relationships between cyclic photophosphorylation, light-induced noncyclic electron transport and energy-dependent NAD-reduction are discussed.

Role of Metabolic Inhibitors on the Adhesion of Rabbit Gel Filtered Platelets to Collagen - Sepharose

1979 ◽  
Author(s):  
J.O. Capobianco ◽  
W.H. Holleman
Keyword(s):  
Metabolic Inhibitors ◽  
Antimycin A ◽  
Inhibitory Effects ◽  
Energy Dependent

The adhesion of rabbit gel filtered platelets (GFP) to collagen-Sepharose was found to be largely energy independent, since metabolic inhibitors only partially suppressed this process. 51Cr and 14C-serotonin labeled GFP were incubated at 37°C/10 min. with anti-metabolites prior to passage over collagen-Sepharose columns. Adhesion and release responses were determined by 51Cr content of columns and 14C content of the supernatant from column eluents. Antimycin-A (AA, 2μg/ml), or AA plus 2-deoxy-D-glucose (2DG, 32mM) or Rotenone (R, 2μg/ml) produced small reductions in adhesion. All three compounds inhibited release, their effects being additive. 2DG or glucono-§-lactone (GLAC, 10mM) alone had little or no effect on adhesion. 2DG reduced release response by 40%, while GLAC had no effect. AA or R reduced adhesion by 35% and 31%, and release by 51% and 47%, respectively. The combination of 2DG, GLAC, AA and R did not reduce adhesion more than 45%. The Inhibitory effects of AA were time and dose related, and the addition c glucose (0.1%) circumvented these effects. These experiments suggest that adhesion includes energy dependent and independent phases. In addition, spherical platelets (GFP at 4°c/24 hrs.) also adhered to collagen-Sepharose; however, in contrast to disc-platelets (GFP at 37°c/10 min.), the adhering platelets demonstrated a depressed release response (-79%),

scholarly journals The active transport of 2-keto-d-gluconate in vesicles prepared from Pseudomonas purida

1985 ◽  
Vol 228 (1) ◽  
pp. 257-262 ◽  
Author(s):  
F Agbanyo ◽  
N F Taylor
Keyword(s):  
Membrane Potential ◽  
Pseudomonas Putida ◽  
Active Transport ◽  
Proton Motive Force ◽  
Electron Donors ◽  
Antimycin A ◽  
Carrier System ◽  
Carbonyl Cyanide ◽  
Km Value ◽  
Phenazine Methosulphate

The transport of 2-keto-D-gluconate (alpha-D-arabino-2-hexulopyranosonic acid; 2KGA) in vesicles prepared from glucose-grown Pseudomonas putida occurs by a saturable process with a Km of 110.0 +/- 2.9 microM and a Vmax. of 0.55 +/- 0.04 nmol X min-1 X (mg of protein)-1. The provision of phenazine methosulphate/ascorbate or L-malate leads to an accumulation of intravescular 2KGA, a decrease in the Km value to 50 +/- 2.1 microM and 35 +/- 2.9 microM respectively and no change in the Vmax. In the presence of electron donors the transport of 2KGA is inhibited by the respiratory poisons antimycin A, rotenone and the uncoupler 2,4-dinitrophenol. 2KGA transport is also competitively inhibited by 4-deoxy-4-fluoro-2-keto- or 3-deoxy-3-fluoro-2-keto-D-gluconate with Ki values of 50 microM and 160 microM respectively. The carrier system for 2KGA is repressed in vesicles from cells grown on succinate. Such vesicles transport 2KGA by non-specific physical diffusion with a Km value of infinity in the absence or presence of electron donors. Vesicles from glucose or succinate grown cells, in the presence of phenazine methosulphate/ascorbate at pH 6.6, generate a proton-motive force (delta p) of approx. 140 mV. The delta p, composed of proton gradient (delta pH) and a membrane potential (delta psi), is collapsed in the presence of dinitrophenol. Based on the results obtained with valinomycin, nigericin and carbonyl cyanide m-chlorophenylhydrazone, the active transport of 2KGA at pH 6.6 is coupled predominately to the delta pH component of delta p.

scholarly journals Generation of superoxide anion by the NADH dehydrogenase of bovine heart mitochondria

1980 ◽  
Vol 191 (2) ◽  
pp. 421-427 ◽  
Author(s):  
J F Turrens ◽  
A Boveris
Keyword(s):  
Cytochrome B ◽  
Nadh Dehydrogenase ◽  
Submitochondrial Particles ◽  
Bovine Heart ◽  
Biphasic Effect ◽  
Carbonyl Cyanide ◽  
Autocatalytic Process ◽  
Ph Range ◽  
Energy Dependent ◽  
O2 Production

Submitochondrial particles from bovine heart in which NADH dehydrogenase is reduced by either addition of NADH and rotenone or by reversed electron transfer generate 0.9 +/- 0.1 nmol of O2-/min per mg of protein at pH 7.4 and at 30 degrees C. When NADH is used as substrate, rotenone, antimycin and cyanide increase O2- production. In NADH- and antimycin-supplemented submitochondrial particles, rotenone has a biphasic effect: it increases O2- production at the NADH dehydrogenase and it inhibits O2- production at the ubiquinone-cytochrome b site. The generation of O2- by the rotenone, the uncoupler carbonyl cyanide rho-trifluoromethoxyphenylhydrazone and oligomycin at concentrations similar to those required to inhibit energy-dependent succinate-NAD reductase. Cyanide did not affect O2- generation at the NADH dehydrogenase, but inhibited O2- production at the ubiquinone-cytochrome b site. Production of O2- at the NADH dehydrogenase is about 50% of the O2- generation but the ubiquinone-cytochrome b area at pH 7.4. Additivity of the two mitochondrial sites of O2- generation was observed over the pH range from 7.0 to 8.8. AN O2–dependent autocatalytic process that requires NADH, submitochondrial particles and adrenaline is described.

Cyanide-resistant respiration in isolated Asparagus mesophyll cells

1984 ◽  
Vol 62 (6) ◽  
pp. 1122-1126 ◽  
Author(s):  
Nancy M. Shadeed ◽  
Alan W. Bown
Keyword(s):  
Alternative Pathway ◽  
Potassium Cyanide ◽  
Antimycin A ◽  
Mesophyll Cells ◽  
Atp Levels ◽  
Energy Conserving ◽  
Sequential Addition ◽  
Tetraethylthiuram Disulfide ◽  
Energy Dependent ◽  
Cyanide Resistant Respiration

The inhibitors of oxidative phosphorylation antimycin A (0.5 μg/mL), oligomycin (0.01 mg/mL), and sodium azide (3 mM) eliminated energy-dependent H+ efflux from isolated Asparagus mesophyll cells. Antimycin A and oligomycin also reduced ATP levels by 60% or more. In contrast the same concentrations of inhibitors had little or no effect on respiratory O2 consumption. The sequential addition of potassium cyanide to give a final concentration of 5.2 μM resulted in a 60% maximum inhibition of O2 consumption. Subsequent addition of 0.2 mM disulfiram (tetraethylthiuram disulfide), a potent inhibitor of cyanide-resistant respiration, resulted in a further reduction of the oxygen consumption rate. In the absence of cyanide, 0.2 mM disulfiram inhibited O2 consumption by 40 to 80%, depending on the suspension medium. Disulfiram had little or no effect on the ATP levels which varied between 0.7 and 2.2 nmol ATP/106 cells. The results indicate that disulfiram inhibits a non-energy-conserving cyanide-resistant alternative pathway in Asparagus mesophyll cells.

scholarly journals Evaluation of the Bioelectrochemical Approach and Different Electron Donors for Biological Trichloroethylene Reductive Dichlorination

Toxics ◽  
2022 ◽  
Vol 10 (1) ◽  
pp. 37
Author(s):  
Edoardo Dell’Armi ◽  
Marta Maria Rossi ◽  
Lucia Taverna ◽  
Marco Petrangeli Papini ◽  
Marco Zeppilli
Keyword(s):  
Reductive Dechlorination ◽  
Molecular Hydrogen ◽  
Batch Reactor ◽  
Electron Donors ◽  
Utilization Efficiency ◽  
Batch Reactors ◽  
Organic Substrates ◽  
Chlorinated Aliphatic Hydrocarbons ◽  
Low Solubility ◽  
Dechlorination Reaction

Trichloroethylene (TCE) and more in general chlorinated aliphatic hydrocarbons (CAHs) can be removed from a contaminated matrix thanks to microorganisms able to perform the reductive dechlorination reaction (RD). Due to the lack of electron donors in the contaminated matrix, CAHs’ reductive dechlorination can be stimulated by fermentable organic substrates, which slowly release molecular hydrogen through their fermentation. In this paper, three different electron donors constituted by lactate, hydrogen, and a biocathode of a bioelectrochemical cell have been studied in TCE dechlorination batch experiments. The batch reactors evaluated in terms of reductive dechlorination rate and utilization efficiency of the electron donor reported that the bio-electrochemical system (BES) showed a lower RD rate with respect of lactate reactor (51 ± 9 µeq/d compared to 98 ± 4 µeq/d), while the direct utilization of molecular hydrogen gave a significantly lower RD rate (19 ± 8 µeq/d), due to hydrogen low solubility in liquid media. The study also gives a comparative evaluation of the different electron donors showing the capability of the bioelectrochemical system to reach comparable efficiencies with a fermentable substrate without the use of other chemicals, 10.7 ± 3.3% for BES with respect of 3.5 ± 0.2% for the lactate-fed batch reactor. This study shows the BES capability of being an alternative at classic remediation approaches.

Further evidence for the existence of cyclic and non-cyclic photophosphorylation in vivo by means of desaspidin and DCMU

1967 ◽  
Vol 22 (5) ◽  
pp. 537-540 ◽  
Author(s):  
W. Urbach ◽  
W. Simonis
Keyword(s):  
Antimycin A ◽  
Anaerobic Conditions ◽  
Intact Cells ◽  
Cyclic Photophosphorylation ◽  
Aerobic And Anaerobic ◽  
Aerobic And Anaerobic Conditions

The effect of desaspidin and DCMU on photophosphorylation in intact cells under aerobic and anaerobic conditions has been studied. Desaspidin is mainly effective in N2 and inhibits under these conditions the DCMU-insensitive cyclic photophosphorylation in vivo like antimycin A. The inhibition of the phosphorylation in light by DCMU is stronger in N2 than in air which suggests a partial existence of oxydative phosphorylation during illumination.

scholarly journals mmpL7 Gene of Mycobacterium tuberculosis Is Responsible for Isoniazid Efflux in Mycobacterium smegmatis

2005 ◽  
Vol 49 (11) ◽  
pp. 4775-4777 ◽  
Author(s):  
Maria R. Pasca ◽  
Paola Guglierame ◽  
Edda De Rossi ◽  
Francesca Zara ◽  
Giovanna Riccardi
Keyword(s):  
Mycobacterium Tuberculosis ◽  
High Resistance ◽  
Mycobacterium Smegmatis ◽  
Efflux Pump ◽  
Gene Encoding ◽  
Resistance Level ◽  
Carbonyl Cyanide ◽  
Resistance Nodulation Division ◽  
Efflux Pump Inhibitors ◽  
Energy Dependent

ABSTRACT The Mycobacterium tuberculosis mmpL7 gene, encoding a hypothetical resistance nodulation division transporter, confers a high resistance level to isoniazid when overexpressed in Mycobacterium smegmatis. The resistance level decreased in the presence of the efflux pump inhibitors reserpine and CCCP (carbonyl cyanide m-chlorophenylhydrazone). Energy-dependent efflux of isoniazid from M. smegmatis cells expressing the mmpL7 gene was observed.

scholarly journals Part of the activating cross-linked immunoglobulin G is internalized by human platelets to sites not accessible for enzymatic digestion

Blood ◽  
1986 ◽  
Vol 67 (1) ◽  
pp. 12-18 ◽  
Author(s):  
MO Spycher ◽  
UE Nydegger
Keyword(s):  
Immunoglobulin G ◽  
Prostaglandin E1 ◽  
Cytochalasin B ◽  
Enzymatic Digestion ◽  
Human Platelets ◽  
Serotonin Release ◽  
Antimycin A ◽  
Energy Dependent ◽  
Increased Susceptibility ◽  
Pronase Treatment

Abstract The differential uptake of tritium-labeled immunoglobulin G (IgG) cross- linked with bisdiazonium-benzidine (BDB) (3H-BDB-IgG) by washed, pooled human platelets to sites inaccessible to pronase digestion was tested. Up to 52% of the 3H-BDB-IgG associated with platelets at 37 degrees C resisted pronase treatment, whereas only 23% of the cross-linked IgG associated with platelets at 4 degrees C, or at 37 degrees C but in the presence of deoxyglucose/antimycin A, remained refractory to pronase. This effect was not due to platelet agglutination. Pronase resistance reached a maximum after a 60-minute incubation period at 37 degrees C. With increasing 3H-BDB-IgG input, both the total cross-linked IgG associated with platelets and the fraction resistant to pronase digestion approached saturation at 4 degrees C, but not at 37 degrees C. The proportion of 3H-BDB-IgG bound to platelets at 4 degrees C that was resistant to pronase treatment increased by 13% within five minutes of warming the platelets to 37 degrees C. Pretreatment of platelets with 10 mmol/L acetylsalicylic acid (or 10 mumol/L prostaglandin E1) prior to the addition of 3H-BDB-IgG led to a 74% (95%) inhibition of the 3H-BDB-IgG-induced 14C-serotonin release, but to only a 44% (49%) inhibition of pronase-digestible bound ligand. In contrast, pretreatment with 10 mumol/L cytochalasin B led to a mere 17% reduction of 14C-serotonin release, whereas acquisition of resistance to pronase digestion by the bound 3H-BDB-IgG was inhibited by 90%. Incubation of platelets at 37 degrees C with 3H-BDB-IgG and removal of unbound material prior to the addition of prostaglandin E1 or deoxyglucose/antimycin A had little effect on the susceptibility of platelet-associated 3H-BDB-IgG to pronase, whereas the addition of cytochalasin B to 3H-BDB-IgG-treated platelets resulted in greatly increased susceptibility of the platelet-associated ligand to pronase. Thus, after binding, 3H-BDB-IgG becomes transferred in an energy- dependent process to pronase-resistant cellular sites, most likely to the open canalicular system.

scholarly journals Modification of Outer Membrane Protein Profile and Evidence Suggesting an Active Drug Pump in Enterobacter aerogenes Clinical Strains

2003 ◽  
Vol 47 (5) ◽  
pp. 1555-1559 ◽  
Author(s):  
Stéphane Gayet ◽  
Renaud Chollet ◽  
Gérard Molle ◽  
Jean-Marie Pagès ◽  
Jacqueline Chevalier
Keyword(s):  
Outer Membrane ◽  
Protein Profile ◽  
Outer Membrane Proteins ◽  
Enterobacter Aerogenes ◽  
Normal Structure ◽  
Clinical Strains ◽  
Resistance Strategies ◽  
Carbonyl Cyanide ◽  
Energy Dependent ◽  
Drug Pump

ABSTRACT Two clinical strains of Enterobacter aerogenes that exhibited phenotypes of multiresistance to β-lactam antibiotics, fluoroquinolones, chloramphenicol, tetracycline, and kanamycin were investigated. Both strains showed a porin pattern different from that of a susceptible strain, with a drastic reduction in the amount of the major porin but with an apparently conserved normal structure (size and immunogenicity), together with overproduction of two known outer membrane proteins, OmpX and LamB. In addition, the full-length O-polysaccharide phenotype was replaced by a semirough Ra phenotype. Moreover, in one isolate the intracellular accumulation of chloramphenicol was increased in the presence of the energy uncoupler carbonyl cyanide m-chlorophenylhydrazone, suggesting an energy-dependent efflux of chloramphenicol in this strain. The resistance strategies used by these isolates appear to be similar to that induced by stress in Escherichia coli cells.

Effect of membrane potential and cellular ATP on glutathione efflux from isolated rat hepatocytes

1988 ◽  
Vol 255 (4) ◽  
pp. G403-G408 ◽  
Author(s):  
J. C. Fernandez-Checa ◽  
C. Ren ◽  
T. Y. Aw ◽  
M. Ookhtens ◽  
N. Kaplowitz
Keyword(s):  
Membrane Potential ◽  
High Performance ◽  
Direct Relationship ◽  
Rat Hepatocytes ◽  
Antimycin A ◽  
Total Glutathione ◽  
Rat Hepatocyte ◽  
Isolated Rat Hepatocytes ◽  
Carbonyl Cyanide ◽  
Isolated Rat

total glutathione (GSH) efflux was studied in isolated rat hepatocyte suspensions at repleted GSH content (45-55 nmol/10(6) cells). The increase in concentrations of medium K+ in place of Na+ caused a parallel fall in membrane potential and total GSH efflux. Ouabain (1 mM) and replacement of Na+ with choline caused a gradual fall in membrane potential and GSH efflux. Hyperpolarization of hepatocytes with lipophilic anions, thiocyanate, and nitrate was associated with significantly increased efflux. Total GSH efflux was inhibited by increasing concentrations of fructose, antimycin A, and carbonyl cyanide p-trifluoromethoxyphenylhydrazone, and there was a direct relationship between the rate of efflux and cellular ATP. Changes in total GSH efflux were paralleled by changes in GSH determined by high-performance liquid chromatography. Vanadate markedly inhibited efflux but caused only a modest decrease in cellular ATP. Fructose, antimycin A, and vanadate did not affect membrane potential or cell volume under the conditions at which efflux was inhibited. These results suggest independent requirements for both membrane potential and ATP in the transport of GSH.

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