| Abstract: | The addition of reducing agents, i.e., ascorbic acid or sodium borohydride, to a DNA solution containing Cu2+ ions causes changes in the DNA absorption spectra which are due to a new absorption band with a maximum at 280 mμ assigned to a DNA base–Cu1+ complex. The stoichiometry of the complex is one Cu1+ ion per four bases of DNA. The DNA–Cu1+ complex has an increased melting temperature and rather different circular dichroism curve as compared with DNA itself. It is inferred that the above effects are caused by proton transfer along the hydrogen bond from guanine to cytosine under complexing of Cu1+ ions with the N7 atom of the guanine of DNA. |
