Infrared Studies of Deoxyribonucleic Acids, their Constituents and Analogues. 4. The Binding Sites of Copper(II) in DNA

The infrared spectra of the four deoxynucleosides dT, dA, dG, and dC have been studied in 2H2O solution without and with addition of CuSO4. The infrared spectra of dT and dA remain unchanged by addition of copper(II), whereas new bands appear at 1,517 and 1,547 cm−1 in the infrared spectrum of dC and at 1,590 cm−1 in the infrared spectrum of dG after addition of CuSO4. The changes in the infrared spectra of DNA from Streptomyces chrysomallus (72 mole% guanine + cytosine) after interaction with copper(II) are very similar to the observed changes in the nucleoside spectra New bands at 1,518 and 1,551 cm−1 indicate the interaction of cytosine bases of DNA with copper(II), the band at 1,590 cm−1 indicates the interaction of guanine bases of DNA with copper(II).