A mechanochemical study of MgDNA fibers in ethanol-water solutions

Schultz, Johan; Rupprecht, A.; Song, Zhiyan; Piškur, Jure; Nordenskiöld, Lars; Lahajnar, G.

doi:10.1016/s0006-3495(94)80857-4

Cited by 22 publications

(24 citation statements)

References 52 publications

(73 reference statements)

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“…3). The minimal value of T, is reached at about 70% ethanol for aggregated MgDNA [29] (Fig. 3) and at about 84% ethanol for aggregated LiDNA [28] (Fig.…”

Section: Thermal Behaviour Of Aggregated Dnamentioning

confidence: 92%

“…Aggregated MgDNA, when reexposed to higher water activities, did not dissolve; instead gelation occurred [29]. Apparently, Mg2+ ions cause very strong aggregation of the DNA helices, an effect due to the high charge of the ion and the resulting increased importance of electrostatic interactions, particularly at high ethanol concentrations [29].…”

Section: Conformational Transitions and Stability Of Dna Aggregatesmentioning

confidence: 98%

“…This method was early modified for the preparation of a long fiber bundle of oriented DNA molecules from which a large number of reproducible samples could be taken for mechanochemical study [26]. Recently, a simple set-up was suggested for mechanochemical studies of conformational and helix-to-coil transitions in such DNA fiber samples [27,28,29,30]. A DNA fiber was held straight by a small weight in a measuring cylinder containing ethanol-water solution.…”

Section: Use Of Highly Oriented Fibersmentioning

confidence: 99%

“…The data are from ref. [29]. 'Once MgDNA has aggregated, it does not redissolve easily, even when he ethanol concentration again is lowered, i.e.…”

Section: Thermal Behaviour Of Aggregated Dnamentioning

confidence: 99%

“…4). The ability to form a thermostable DNA structure at high ethanol concentrations is influenced by the nature of the counterion and decreases in the order: Mg" > Li' > Na' > K' > Cs' [28,29]. This behaviour may be explained as follows: before the critical concentration of ethanol is reached the aggregation forces are only moderately strong and single strands of the aggregated DNA can slip past each other in the endeavour to form a random coil upon thermal treatment, yielding fiber contraction.…”

Section: Aggregated Dna At Very High Ethanol Concentrationmentioning

confidence: 99%

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Aggregated DNA in ethanol solution

Piškur

Rupprecht

1995

FEBS Letters

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A recently developed mecbanocbemical method has provided a new, efficient tool for studies on the thermal stability and structure of aggregated DNA in ethanol-water solutions. At low ethanol concentrations DNA is fully soluble and is in the B form. However, with increasing ethanol concentration the melting temperature of DNA, T,,,, decreases. At a critical ethanol concentration, dependent on the nature and concentration of the counterion, aggregation of the DNA molecules sets in. This is reflected in a marked increase in T,,, indicating that the aggregated DNA molecules are thermally more stable than the dissolved ones. However, they are still in the B form. In general, T,,, of aggregated DNA also decreases with further increasing ethanol concentration and is dependent on the nature of the counterion, but T,,, is not affected by the concentration of the counterion (excess salt) in the ethanol-water solution. When the ethanol concentration reaches the range of 7040% (v/v), the B-to-A conformational transition occurs in the case of Na-, K-and CsDNA. Above this transition point the A form is more stable than the B form due to the reduced water activity and to increased interhelical interactions. At very high ethanol concentrations, above 85% and dependent on the nature of the counterion, a drastic change in the thermal behaviour is observed. Apparently such a strong interhelical interaction is induced in the aggregated DNA that the DNA is stabilized and cannot adopt a random coil state even at very high temperatures. This stability of DNA in the P form is fully reversed if the ethanol concentration is lowered and the activity of water, thereby, is restored.

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“…3). The minimal value of T, is reached at about 70% ethanol for aggregated MgDNA [29] (Fig. 3) and at about 84% ethanol for aggregated LiDNA [28] (Fig.…”

Section: Thermal Behaviour Of Aggregated Dnamentioning

confidence: 92%

Section: Conformational Transitions and Stability Of Dna Aggregatesmentioning

confidence: 98%

Section: Use Of Highly Oriented Fibersmentioning

confidence: 99%

“…The data are from ref. [29]. 'Once MgDNA has aggregated, it does not redissolve easily, even when he ethanol concentration again is lowered, i.e.…”

Section: Thermal Behaviour Of Aggregated Dnamentioning

confidence: 99%

Section: Aggregated Dna At Very High Ethanol Concentrationmentioning

confidence: 99%

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Aggregated DNA in ethanol solution

Piškur

Rupprecht

1995

FEBS Letters

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Solvent Interactions with Proteins and Other Macromolecules

Ohtake

Kita

Tsumoto

et al. 2011

Amino Acids, Peptides and Proteins in Organic Chemistry

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Mechanochemical study of conformational transitions and melting of Li‐, Na‐, K‐, and CsDNA fibers in ethanol–water solutions

et al. 1994

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SYNOPSISHighly oriented fibers of Li-, Na-, K-, and CsDNA were prepared with a previously developed wet spinning method. The procedure gave a large number of equivalent fiber bundle samples (reference length, Lo, typically = 12-15 cm) for systematic measurements of the fiber length L in ethanol-water solutions, using a simple mechanochemical set up. The decrease in relative length L / Lo with increasing ethanol concentration at room temperature gave evidence for the B-A transition centered at 76% ( v / v ) ethanol for NaDNA fibers and at 80 and 84% ethanol for Kand CsDNA fibers. A smaller decrease in L / L o of LiDNA fibers was attributed to the B-C transition centered at 80% ethanol. In a second type of experiment with DNA fibers in ethanol-water solutions, the heat-induced helix-coil transition, or melting, revealed itself in a marked contraction of the DNA fibers. The melting temperature T,, decreased linearly with increasing ethanol concentration for fibers in the B-DNA ethanol concentration region. In the B-A transition region, Na-and KUNA fibers showed a local maximum in T,. On further increase of the ethanol concentration, the A-DNA region followed with an even steeper linear decrease in T,. The dependence on the identity of the counterion is discussed with reference to the model for groove binding of cations in B-DNA developed by Skuratovskii and co-workers and to the results from Raman studies of the interhelical bonds in A-DNA performed by Lindsay and co-workers. An attempt to apply the theory of Chogovadze and Frank-Kamenetskii on DNA melting in the B-A transition region to the curves failed. However, for Na-and KDNA the T , dependence in and around the A-B transition region could be expressed as a weighted mean value of T , of Aand B-DNA. On further increase of the ethanol concentration, above 84% ethanol for LiDNA and above about 90% ethanol for Na-, K-, and CsDNA, a drastic change occurred. T , increased and a few percentages higher ethanol concentrations were found to stabilize the DNA fibers so that they did not melt at all, not even at the upper temperature limit of the experiments ( -80°C). This is interpreted as being due to the strong aggregation induced by these high ethanol concentrations and to the formation of P-DNA. Many features of the results are compatible with the counterion-water affinity model. In another series of measurements, T,,, of DNA fibers in 75% ethanol was measured at various salt concentrations. No salt effect was observed (with the exception of LiDNA at low salt concentrations). This result is supported hy calculations within the Poisson-Roltzmann cylindrical cell model.

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A mechanochemical study of MgDNA fibers in ethanol-water solutions

Cited by 22 publications

References 52 publications

Aggregated DNA in ethanol solution

Aggregated DNA in ethanol solution

Solvent Interactions with Proteins and Other Macromolecules

Mechanochemical study of conformational transitions and melting of Li‐, Na‐, K‐, and CsDNA fibers in ethanol–water solutions

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