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Updated: Aug 20, 2026
CD Spectroscopy to Study DNA-Protein Interactions
Published on: February 10, 2022
In situ measurement of circular dichroism of DNA adsorbing onto a solid surface
Jun-ichi Horinaka1, Hiromichi Nakura, Shiro Maeda
1Department of Material Chemistry, Graduate School of Engineering, Kyoto University, Nishikyo, Kyoto 615-8510, Japan. horinaka@rheogate.polym.kyoto-u.ac.jp <horinaka@rheogate.polym.kyoto-u.ac.jp>
Abstract:
The adsorption process of DNA dissolved in aqueous solutions onto the surface of polyethyleneimine (PEI) has been examined by the observation of in situ circular dichroism (CD), including time-resolved measurements, to elucidate the conformation of DNA at the liquid/solid interface. The adsorption process can be characterized by two stages that are characterized in terms of CD. In the first stage, time (t)<700 s, a slight change in the time-resolved CD spectra of DNA is observed, whereas the value of the induced CD of the dye intercalated in DNA is constant. This result can be explained by the interaction between DNA and PEI during the adsorption at the liquid/solid interface. The weakness of the interaction is attributed to the geometrical restriction of this interface. In the second stage, t>700 s, where no further adsorption occurs, a change in the induced CD as well as in the CD of DNA is observed. This change in the induced CD can be interpreted as a significant conformational change of DNA for stabilizing the ion complex with PEI.
