Dependence of the melting temperature of DNA on salt concentration
Author: Schildkraut, C. Description: Data on the decrease of the DNA melting temperature Tm with the salt concentration M are reported and discussed. The electrostatic free energy change in the helix–coil transition, ΔFe is related to the potential, ψ, which represents the electrostatic repulsion between the phosphate charges; ψ is calculated as a function of M and of the distances between the charges of the two strands. The Debye-Hückel approximation is shown to overestimate ψ. It is suggested that the high local concentration of the counterions in the immediate vicinity…
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