Mineralization of [14C]octacosane by Acinetobacter calcoaceticus S30

1996 ◽  
Vol 42 (12) ◽  
pp. 1225-1231 ◽  
Author(s):  
Banwari Lal ◽  
Sunil Khanna
Keyword(s):  
Doubling Time ◽  
Acinetobacter Calcoaceticus ◽  
Metabolic Inhibitors ◽  
Acid Uptake ◽  
Sulphydryl Group ◽  
Whole Cells ◽  
Cell Biomass ◽  
Intermediate Metabolites ◽  
Transport Inhibitors ◽  
Energy Dependent

Acinetobacter calcoaceticus S30 could grow (doubling time, 7 h) on octacosane (C28) and degraded about 70% of the substrate during growth. Octacosanol, octacosanoic acid, and other lower carboxylic acids were identified during degradation of octacosane. Acinetobacter calcoaceticus S30 could also grow on intermediate metabolites, namely octacosanol and octacosanoic acid, although the doubling time was greater on octacosanoic acid (72 h on octacosanol and 120 h on octacosanoic acid). Whole cells of A. calcoaceticus S30 using [18-14C]octacosane mineralized 65% of the octacosane to 14CO2 and 30% of the radiolabel was retained in the cell biomass in 24 h. Acinetobacter calcoaceticus S30 converts octacosane to octacosanol through an oxidation step, which is then oxidized to octacosanoic acid and then β-oxidized to CO2. Among several metabolic inhibitors, those of the sulphydryl group greatly inhibited the uptake of octacosanol and octacosanoic acid at much lower concentrations. The electron transport inhibitors were potent inhibitors of octacosane, octacosanol, and octacosanoic acid uptake, suggesting that the oxidation of these substrates is an energy-dependent process.Key words: Acinetobacter calcoaceticus, mineralization, octacosane, octacosanol, octacosanoic acid.

Mineralization of [14C]octadecane by Acinetobacter calcoaceticus S19

1998 ◽  
Vol 44 (7) ◽  
pp. 681-686 ◽  
Author(s):  
Urmi Bajpai ◽  
R C Kuhad ◽  
Sunil Khanna
Keyword(s):  
Doubling Time ◽  
Acinetobacter Calcoaceticus ◽  
Octadecanoic Acid ◽  
Anaerobic Conditions ◽  
Whole Cells ◽  
Absolute Requirement

Uptake of octadecane by Acinetobacter calcoaceticus S19 was found to be 70% during growth (doubling time of 4 h), of which 60% was incorporated into the cells and 40% was oxidized to 14CO2. The ratio of [14C]octadecane uptake to its mineralization by whole cells was similar to that found during the growth of A. calcoaceticus S19. After 4 h of incubation of cells with [14C]octadecane, 44% was mineralized to 14CO2, while the rest remained associated with the cells. Octadecane uptake was not observed under anaerobic conditions, indicating an absolute requirement for oxygen. Acinetobacter calcoaceticus S19 converted octadecane to the corresponding octadecanol and octadecanoic acid; the corresponding aldehyde was not detected, however. Octadecanoic acid was partially degraded through β-oxidation to CO2 and partly assimilated as cell biomass.Key words: Acinetobacter calcoaceticus, octadecane uptake, mineralization.

scholarly journals Biocatalyst Engineering by Assembly of Fatty Acid Transport and Oxidation Activities for In Vivo Application of Cytochrome P-450BM-3 Monooxygenase

1998 ◽  
Vol 64 (10) ◽  
pp. 3784-3790 ◽  
Author(s):  
Silke Schneider ◽  
Marcel G. Wubbolts ◽  
Dominique Sanglard ◽  
Bernard Witholt
Keyword(s):  
Fatty Acids ◽  
Fatty Acid ◽  
Coenzyme A ◽  
Fatty Acid Uptake ◽  
Acid Uptake ◽  
Uptake System ◽  
Whole Cells ◽  
E Coli ◽  
Cytochrome P 450 ◽  
Long Chain

ABSTRACT The application of whole cells containing cytochrome P-450BM-3 monooxygenase [EC 1.14.14.1 ] for the bioconversion of long-chain saturated fatty acids to ω-1, ω-2, and ω-3 hydroxy fatty acids was investigated. We utilized pentadecanoic acid and studied its conversion to a mixture of 12-, 13-, and 14-hydroxypentadecanoic acids by this monooxygenase. For this purpose,Escherichia coli recombinants containing plasmid pCYP102 producing the fatty acid monooxygenase cytochrome P-450BM-3were used. To overcome inefficient uptake of pentadecanoic acid by intact E. coli cells, we made use of a cloned fatty acid uptake system from Pseudomonas oleovorans which, in contrast to the common FadL fatty acid uptake system of E. coli, does not require coupling by FadD (acyl-coenzyme A synthetase) of the imported fatty acid to coenzyme A. This system fromP. oleovorans is encoded by a gene carried by plasmid pGEc47, which has been shown to effect facilitated uptake of oleic acid in E. coli W3110 (M. Nieboer, Ph.D. thesis, University of Groningen, Groningen, The Netherlands, 1996). By using a double recombinant of E. coli K27, which is a fadDmutant and therefore unable to consume substrates or products via the β-oxidation cycle, a twofold increase in productivity was achieved. Applying cytochrome P-450BM-3 monooxygenase as a biocatalyst in whole cells does not require the exogenous addition of the costly cofactor NADPH. In combination with the coenzyme A-independent fatty acid uptake system from P. oleovorans, cytochrome P-450BM-3 recombinants appear to be useful alternatives to the enzymatic approach for the bioconversion of long-chain fatty acids to subterminal hydroxylated fatty acids.

scholarly journals Mechanism and regulation of folate uptake by pancreatic acinar cells: effect of chronic alcohol consumption

2010 ◽  
Vol 298 (6) ◽  
pp. G985-G993 ◽  
Author(s):  
Hamid M. Said ◽  
Lisa Mee ◽  
V. Thillai Sekar ◽  
Balasubramaniem Ashokkumar ◽  
Stephen J. Pandol
Keyword(s):  
Acinar Cells ◽  
Pancreatic Acinar Cell ◽  
Pancreatic Acinar Cells ◽  
Exocrine Function ◽  
Acid Uptake ◽  
Human Pancreas ◽  
Chronic Alcohol ◽  
Transport Inhibitors ◽  
Pancreatic Exocrine ◽  
One Carbon Metabolism

Folate plays an essential role in one-carbon metabolism, and a relationship exists between methyl group metabolism and pancreatic exocrine function. Little, however, is known about the mechanism(s) and regulation of folate uptake by pancreatic acinar cells and the effect of chronic alcohol use on the process. We addressed these issues using the rat-derived pancreatic acinar cell line AR42J and freshly isolated primary rat pancreatic acinar cells as models. We found [3H]folic acid uptake to be 1) temperature and pH dependent with a higher uptake at acidic than at neutral/alkaline pH; 2) saturable as a function of substrate concentration at both buffer pH 7.4 and 6.0; 3) inhibited by folate structural analogs and by anion transport inhibitors at both buffer pH 7.4 and 6.0; 4) trans-stimulated by unlabeled folate; 5) adaptively regulated by the prevailing extracellular folate level, and 6) inhibited by modulators of the cAMP/PKA-mediated pathway. Both the reduced folate carrier (RFC) and the proton-coupled folate transporter (PCFT) were found to be expressed in AR42J and in primary pancreatic acinar cells, as well as in native human pancreas with expression of RFC being higher than PCFT. Chronic alcohol feeding of rats (4 wk; 36% of calories from ethanol) led to a significant decrease in folate uptake by freshly isolated primary pancreatic acinar cells compared with cells from pair-fed controls; this effect was associated with a parallel decrease in the level of expression of RFC and PCFT. These studies reveal that folate uptake by pancreatic acinar cells is via a regulated carrier-mediated process which may involve RFC and PCFT. In addition, chronic alcohol feeding leads to a marked inhibition in folate uptake by pancreatic acinar cells, an effect that is associated with reduction in level of expression of RFC and PCFT.

Energy dependence of RNA degradation in rabbit reticulocytes

1984 ◽  
Vol 247 (5) ◽  
pp. C390-C395 ◽  
Author(s):  
E. A. Park ◽  
H. E. Morgan
Keyword(s):  
Protein Synthesis ◽  
Ribosomal Rna ◽  
Rna Degradation ◽  
Atp Depletion ◽  
Metabolic Inhibitors ◽  
Atp Content ◽  
Bicarbonate Buffer ◽  
Ribosomal Subunits ◽  
Energy Dependent ◽  
Rabbit Reticulocytes

RNA degradation in rabbit reticulocytes was partially energy dependent. Reticulocytes were incubated for 10 h in Krebs-Henseleit bicarbonate buffer that was gassed with 95% O2-5% CO2 and contained glucose (30 mM) or 2-deoxyglucose (20 mM) and 2,4-dinitrophenol (0.2 mM). The rate of RNA degradation was reduced 41% in the presence of the metabolic inhibitors. When the buffer was gassed with 95% N2-5% CO2 and no substrate was added, the disappearance of RNA was decreased 55%. The cellular ATP content was depleted either by addition of the metabolic inhibitors or by incubation under anoxic conditions. ATP depletion did not modify the ratio of ribosomal subunits + monomers to polysomes. Puromycin and cycloheximide, which increased or decreased, respectively, the proportion of ribosomal RNA in subunits + monomers, blocked protein synthesis but did not alter the rate of RNA degradation. These experiments indicated that energy depletion inhibited RNA degradation by a mechanism that did not depend on the inhibition of protein synthesis. No evidence was obtained to indicate that the ratio of subunits + monomers to polysomes affected RNA degradation.

Energy-dependent cell volume maintenance in UC-11MG human astrocytomas

1989 ◽  
Vol 257 (4) ◽  
pp. C817-C824 ◽  
Author(s):  
R. Lomneth ◽  
E. I. Gruenstein
Keyword(s):  
Cell Volume ◽  
Glucose Deprivation ◽  
Atp Depletion ◽  
Metabolic Inhibitors ◽  
Rapid Phase ◽  
Atp Levels ◽  
Time Period ◽  
Astrocytoma Cell ◽  
Dependent Cell ◽  
Energy Dependent

Swelling of astrocytes in the brain is a major cause of the morbidity and mortality associated with stroke and head trauma. Using a human astrocytoma cell line (UC-11MG) as a model system, we studied cell volume changes caused by ATP depletion under conditions mimicking hypoxia. ATP levels were reduced to less than 10% of control using the metabolic inhibitors KCN or antimycin in combination with glucose deprivation. This was sufficient to eliminate ouabain-sensitive 86Rb+ uptake, indicating the Na+-K+-adenosinetriphosphatase was not operating. Furosemide-sensitive 86Rb+ uptake was reduced by approximately 60%, indicating Na+-K+-2Cl- cotransport was also sensitive to ATP loss. ATP depletion resulted in a 30-40% reduction of cell volume within 60 min. ATP depletion also resulted in a net loss of intracellular K+. This loss of K+ could be blocked by Ba2+, indicating the K+ loss was through a conductive channel. When the net K+ loss was blocked by Ba2+, the volume decrease was also prevented. The cells remained viable throughout the time period as judged by exclusion of ethidium bromide by 99% of the cells and recovery of ATP levels to 75% of control within 60 min. We conclude that ATP depletion, following inhibition of glycolysis and oxidative phosphorylation, causes astrocytes to shrink because of a more rapid loss of K+ than uptake of Na+. Thus it appears that ATP depletion alone is not sufficient to account for the rapid phase of astrocytic swelling observed during cerebral ischemia.

ACTIVE TRANSPORT OF ASCORBIC ACID IN ADRENAL CORTEX AND BRAIN CORTEX IN VITRO AND THE EFFECTS OF ACTH AND STEROIDS

1963 ◽  
Vol 41 (1) ◽  
pp. 597-604 ◽  
Author(s):  
Shail K. Sharma ◽  
R. M. Johnstone ◽  
J. H. Quastel
Keyword(s):  
Ascorbic Acid ◽  
Adrenal Cortex ◽  
Active Transport ◽  
Brain Cortex ◽  
Acid Uptake ◽  
Dependent Process ◽  
Brain Cortex Slices ◽  
Cortex Slices ◽  
Energy Dependent

Uptake of ascorbic acid-1-C14in brain cortex and adrenal cortex slices is an energy-dependent process. Concentration ratios (i.e. ratios of tissue ascorbic acid-1-C14to medium ascorbic acid-1-C14) greater than 4 have been obtained with both tissues in vitro. Ouabain as well as 2, 4-dinitrophenol suppresses ascorbic acid uptake into brain cortex slices.ACTH inhibits the uptake of ascorbic acid-1-C14in adrenal cortex, but not in brain cortex slices. The presence of glucose is necessary for the inhibition. Several cortical steroids, as well as adenosine-3′,5′-monophosphate, at small concentrations inhibit the uptake. The results are consistent with the interpretation that ACTH inhibits the uptake of ascorbic acid in the adrenal cortex through the steroids produced in its presence.

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 Nona-Arginine Facilitates Delivery of Quantum Dots into Cells via Multiple Pathways

2010 ◽  
Vol 2010 ◽  
pp. 1-11 ◽  
Author(s):  
Yi Xu ◽  
Betty Revon Liu ◽  
Han-Jung Lee ◽  
Katie B. Shannon ◽  
Jeffrey G. Winiarz ◽  
...  
Keyword(s):  
Quantum Dots ◽  
Cellular Uptake ◽  
Metabolic Inhibitors ◽  
Cellular Internalization ◽  
Caveolin 1 ◽  
Dependent Process ◽  
A Cell ◽  
Low Efficiency ◽  
Rnai Technique ◽  
Energy Dependent

Semiconductor quantum dots (QDs) have recently been used to deliver and monitor biomolecules, such as drugs and proteins. However, QDs alone have a low efficiency of transport across the plasma membrane. In order to increase the efficiency, we used synthetic nona-arginine (SR9), a cell-penetrating peptide, to facilitate uptake. We found that SR9 increased the cellular uptake of QDs in a noncovalent binding manner between QDs and SR9. Further, we investigated mechanisms of QD/SR9 cellular internalization. Low temperature and metabolic inhibitors markedly inhibited the uptake of QD/SR9, indicating that internalization is an energy-dependent process. Results from both the pathway inhibitors and the RNA interference (RNAi) technique suggest that cellular uptake of QD/SR9 is predominantly a lipid raft-dependent process mediated by macropinocytosis. However, involvement of clathrin and caveolin-1 proteins in transducing QD/SR9 across the membrane cannot be completely ruled out.

Relationships of Adenine Nucleotide Metabolism to Platelet-Collagen Adhesion

1978 ◽  
Vol 39 (02) ◽  
pp. 366-378 ◽  
Author(s):  
Robert J Morin ◽  
Albert F T Chen
Keyword(s):  
Oxidative Phosphorylation ◽  
Major Part ◽  
Adenine Nucleotide ◽  
Nucleotide Metabolism ◽  
Collagen Fibrils ◽  
Metabolic Inhibitors ◽  
Adenine Nucleotide Metabolism ◽  
Energy Dependent ◽  
Adhesion Of Platelets ◽  
Adhesion Process

SummaryAdhesion of platelets to collagen fibrils in a stirred system was inhibited by preincubation of platelets with combinations of 2-deoxy-D-glucose and oligomycin or antimycin. The inhibition of adhesion was associated with a decrease in metabolic ATP to 6% of control levels. Without metabolic inhibitors, platelets adherent to collagen fibrils were found to have catabolized approximately 57% of their metabolic ATP, and converted a major part of this to IMP. Storage pool ATP and ADP contents were also diminished in the adherent platelets. Pretreatment with imipramine resulted in 76% inhibition of the release reaction, but only 5% inhibition of adhesion. Imipramine-treated platelets that were adherent to collagen showed significant depletion of metabolic ATP, but markedly diminished conversion of ATP to IMP as compared to control adherent platelets. Inhibition of deamination of platelet AMP by coformycin or erythro-9-(2-hydroxy-3-nonyl) adenine (EHNA) did not inhibit adhesion, although platelets adherent to collagen after treatment with these agents showed depletion of metabolic ATP. These studies suggest that adhesion is an energy dependent process, occurring independently of release, and not associated with conversion of ATP to IMP. The energy dependent portions of the adhesion process are probably disc to sphere transformation and pseudopod formation, the ATP threshold requirement is relatively low, and the ATP utilized can probably be regenerated during the adhesion process via glycolysis and oxidative phosphorylation.

scholarly journals MACROMOLECULAR ABSORPTION

1972 ◽  
Vol 54 (2) ◽  
pp. 195-205 ◽  
Author(s):  
W. A. Walker ◽  
R. Cornell ◽  
L. M. Davenport ◽  
K. J. Isselbacher
Keyword(s):  
Biologically Active ◽  
Metabolic Inhibitors ◽  
Passive Immunity ◽  
Limited Capacity ◽  
Uptake Mechanism ◽  
Adult Rats ◽  
Large Molecules ◽  
Adult Rat ◽  
Energy Dependent ◽  
Rat Gut

The immature small intestine of neonatal mammals is permeable to gamma globulins as a source of passive immunity. Allegedly, macromolecular absorption ceases when the epithelial cell membrane matures. However, some evidence exists that adult animals retain a limited capacity to transport antigenic and biologically active quantities of large molecules. In this study, the mechanism of absorption of the tracer protein, horseradish peroxidase (HRP), was tested in neonatal and adult rat gut sacs. Transport into serosal fluid was quantitated by enzymatic assay and monitored morphologically by histochemical techniques. A greater transport of HRP was noted in the adult jejunum compared to adult ileum and neonatal intestine. Morphologically, the uptake mechanism in adult intestine was similar to the endocytosis previously reported in neonatal animals Like other endocytotic processes, HRP uptake in adult rats is an energy-dependent process as determined by metabolic inhibitors and temperature-controlled studies. An understanding of the mechanism whereby macromolecules are bound to intestinal membranes and engulfed by them is necessary before the action of physiologic macromolecules such as enterotoxins can be appreciated.

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