The conformational change of DNA in aqueous alcohol solutions containing metallic ions determined by using differential scanning calorimeter

• Published in: Thermochimica acta 1990-06, Vol.163, p.147-154
• Main Authors: Matsuoka, Yasuhiro, Nomura, Akihiko, Tanaka, Shigeyuki, Baba, Yoshihiro, Kagemoto, Akihiro
• Format: Article
• Language: English
• ISSN: 0040-6031; 1872-762X
• DOI: 10.1016/0040-6031(90)80391-B

In order to obtain information about the conformational change of DNA by changing the environment surrounding DNA molecule, we measured the helix-coil transition of DNA solutions with various concentrations of ethanol at a given concentration of various kinds of metallic ion by means of an adiabatic differential scanning calorimeter. The observed heat of transition, ΔH increases, but the transition temperature, T 1 decreases with increasing the concentration of ethanol, demonstrating that the conformation of DNA may considerably change by environment surrounding DNA. In order to confirm the conformational change of DNA, we also measured the CD spectra at room temperature under the same experimental conditions as the DSC measurement. The concentration range of ethanol where molecular ellipticity ratio, [θ] max/[θ] min of positive maximum, [θ] max to negative minimum, [θ] min changes is in good agreement with that obtained from DSC measurements. We will discuss the conformational change of DNA in solutions with various proportions of ethanol and a definite concentration of metallic ion by combining the results obtained by the calorimetric and spectral measurements.