Osmotic Effectors and DNA Structure: Effect of Glycine on Precipitation of DNA by Multivalent Cations

Flock, S.; Labarbe, Rudi; Houssier, Claude

doi:10.1080/07391102.1995.10508823

Cited by 25 publications

(21 citation statements)

References 32 publications

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“…The above predictions from the TBI theory are in accordance with the experimental observations (31,35,96,106,107). In the experiments, the addition of methanol, alcohol, and urea may influence not only the dielectric constant (the polarization of solvent molecules), but also the ion-binding specificity (hydrogenbond mediated ion-nucleic acid interaction).…”

Section: Dielectric Constant Dependence Of Helix-helix Attractionsupporting

confidence: 84%

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Ion-Mediated Nucleic Acid Helix-Helix Interactions

Tan

Chen

2006

Biophysical Journal

199

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Salt ions are essential for the folding of nucleic acids. We use the tightly bound ion (TBI) model, which can account for the correlations and fluctuations for the ions bound to the nucleic acids, to investigate the electrostatic free-energy landscape for two parallel nucleic acid helices in the solution of added salt. The theory is based on realistic atomic structures of the helices. In monovalent salt, the helices are predicted to repel each other. For divalent salt, while the mean-field Poisson-Boltzmann theory predicts only the repulsion, the TBI theory predicts an effective attraction between the helices. The helices are predicted to be stabilized at an interhelix distance approximately 26-36 A, and the strength of the attractive force can reach -0.37 k(B)T/bp for helix length in the range of 9-12 bp. Both the stable helix-helix distance and the strength of the attraction are strongly dependent on the salt concentration and ion size. With the increase of the salt concentration, the helix-helix attraction becomes stronger and the most stable helix-helix separation distance becomes smaller. For divalent ions, at very high ion concentration, further addition of ions leads to the weakening of the attraction. Smaller ion size causes stronger helix-helix attraction and stabilizes the helices at a shorter distance. In addition, the TBI model shows that a decrease in the solvent dielectric constant would enhance the ion-mediated attraction. The theoretical findings from the TBI theory agree with the experimental measurements on the osmotic pressure of DNA array as well as the results from the computer simulations.

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Section: Dielectric Constant Dependence Of Helix-helix Attractionsupporting

confidence: 84%

“…Various experiments have demonstrated the important role of the dielectric property of solvent in DNA condensation (31,35,96,106,107). For example, experiments have shown that the addition of methanol in solvent favors the ion-mediated DNA condensation and aggregations (31,35,96).…”

Section: Dielectric Constant Dependence Of Helix-helix Attractionmentioning

confidence: 99%

Ion-Mediated Nucleic Acid Helix-Helix Interactions

Tan

Chen

2006

Biophysical Journal

199

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“…Cellular loss of organic osmolytes does not only contribute to cell shrinkage but may favour destabilization of proteins and may thus participate in the dismantling of the cell during apoptosis [5,7,14]. However, without specific inhibitors the contribution of taurine release to any event of apoptosis cannot be evaluated adequately.…”

Section: Discussionmentioning

confidence: 97%

The involvement of caspases in the CD95(Fas/Apo-1)- but not swelling-induced cellular taurine release from Jurkat T-lymphocytes

Läng

Madlung

Siemen

et al. 2000

Pflugers Arch - Eur J Physiol

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Following a delay of 45 min, stimulation of the CD95 (Fas/Apo-1)-receptor in Jurkat T-lymphocytes leads to the release of the osmolyte taurine, an event coinciding with apoptotic cell shrinkage. The present study has been performed to elucidate the cellular mechanisms involved in CD95-induced taurine release as compared to swelling-induced taurine release, and to explore whether taurine modifies apoptotic DNA fragmentation and cell shrinkage. Taurine release stimulated by osmotic cell swelling is insensitive to the tyrosine kinase inhibitor herbimycin A and the caspase inhibitor z-Val-Ala-Asp(OMe)-fluoromethylketone (zVAD) but is blunted in the absence of extracellular Ca2+. Conversely, the Ca2+ ionophore ionomycin stimulates taurine release. However, the taurine release following CD95 stimulation is not paralleled by an increase of cytosolic Ca2+ and not inhibited by complexation of extracellular Ca2+. None of herbimycin A, the phosphatase inhibitor vanadate, spingomyelinase or Lck56 deficiency prevent CD95-induced taurine release. In contrast, the caspase inhibitor zVAD, but not the caspase inhibitor Ac-Tyr-Val-Ala-Asp-chloromethylketone (YVAD), almost abolishes CD95-induced taurine release. Both caspase inhibitors blunt CD95-induced cell shrinkage and DNA fragmentation, zVAD being more effective than YVAD. Preloading of the cells with 40 mM taurine but not with 40 mM mannitol significantly inhibits CD95-induced DNA fragmentation (by 28%) and apoptotic cell shrinkage (by 25%). In conclusion, CD95-receptor triggering leads to caspase-dependent stimulation of cellular taurine release, which facilitates, but is not sufficient for, the triggering of apoptotic DNA fragmentation and cell shrinkage.

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“…Organic osmolytes stabilize proteins, counteracting the adverse effects of inorganic and organic ions [1,7,8,10,12,22,38,39]. Possibly, destabilization of proteins participates in the disintegration of apoptotic cells.…”

Section: Discussionmentioning

confidence: 98%

Cellular taurine release triggered by stimulation of the Fas(CD95) receptor in Jurkat lymphocytes

Läng

Madlung

Uhlemann

et al. 1998

Pfl�gers Archiv European Journal of Physiology

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One of the hallmarks of apoptosis is cell shrinkage which appears to be important for cell death. The mechanisms mediating cell volume decrease have, however, not been addressed. Mechanisms employed by swollen cells to decrease their cell volume include activation of ion transport pathways, such as ion channels and KCl cotransport, and release of cellular osmolytes, such as taurine, sorbitol, betaine and inositol. The present study has been performed to test for release of taurine. To this end Jurkat human T-lymphocytes were loaded with [3H]taurine and apoptotic cell death induced by triggering the Fas(CD95) receptor with monoclonal crosslinking antibody. Triggering the Fas(CD95) receptor led to a release of 60+/-5% of cellular taurine within 90 min. The release did not occur prior to 45 min. The release coincided with cell shrinkage as evidenced from forward scatter in FACS analysis and preceeded DNA fragmentation according to propidium iodide staining. The delay of taurine release was not influenced by exchange of medium and thus was not due to extracellular accumulation of a stimulator. The Fas(CD95)-induced taurine release, cell shrinkage and DNA fragmentation were blunted by lowering of ambient temperature to 23 degreesC. Following pretreatment of cells with Fas(CD95) antibody at 23 degreesC rewarming led to rapid taurine release, cell shrinkage and DNA fragmentation, indicating that the temperature-sensitive step is distal to the mechanisms accounting for the delay. Osmotic cell swelling led to an immediate release of taurine. In conclusion, Fas(CD95) triggering leads to delayed taurine release through a temperature-sensitive mechanism.

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Osmotic Effectors and DNA Structure: Effect of Glycine on Precipitation of DNA by Multivalent Cations

Cited by 25 publications

References 32 publications

Ion-Mediated Nucleic Acid Helix-Helix Interactions

Ion-Mediated Nucleic Acid Helix-Helix Interactions

The involvement of caspases in the CD95(Fas/Apo-1)- but not swelling-induced cellular taurine release from Jurkat T-lymphocytes

Cellular taurine release triggered by stimulation of the Fas(CD95) receptor in Jurkat lymphocytes

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