Raman spectroscopic study of the effects of Ca2+, Mg2+, Zn2+, and Cd2+ ions on calf thymus DNA: Binding sites and conformational changes

✍ Scribed by Marc Langlais; Heidar All Tajmir-Riahi; Rodrigue Savoie

• Publisher: Wiley (John Wiley & Sons)
• Year: 1990
• Tongue: English
• Weight: 903 KB
• Volume: 30
• Category: Article
• ISSN: 0006-3525
• DOI: 10.1002/bip.360300709

✦ Synopsis

The interaction of Mg2+, Ca2+, Zn2+, and Cd2' with calf thymus DNA has been investigated by Raman spectroscopy. These spectra reveal that all of these ions, and particularly Zn2+, bind to phosphate groups of DNA, causing a slight structural change in the polynucleotide at very small metal : D N A ( P ) concentration ratio ( c a . 1 : 3 0 ) . This results in increased base-stacking interactions, with negligible change of the B conformation of DNA. Contrary to ZnZ+ and Cd2+, which interact extensively with the nucleic bases (particularly at the N7 position of guanine), the alkaline-earth metal ions are bound almost exclusively to the phosphate groups. The affinity of both the Zn2+ and Cd2+ ions for G -C base pairs is comparable, but the Cd2+ ions interact more extensively with A -T pairs than Zn2+ ions. Interstrand cross-linking through the N3 atom of cytosine is suggested in the presence of Zn2+, but not Cd2+.