[Interaction of immobilized DNA with silver ions]

The interaction of Ag+ with DNA immobilized in polyacrylamide gel was studied by means of the ion-exchange method. Ag+ ions are shown to bind to DNA bases, their charges being neutralized by phosphate groups. The binding sites of Ag+ and H+ are likely to be the same, but the strength of Ag+ binding is greater than that of H+. Ag+ ions like H+ are shown to cause the formation of compact structures in immobilized DNA, the amount of these structures being dependent on subtle differences in DNA samples. DNA samples, not forming compact structures under the influence of H+, do not form them under the influence of Ag+. This fact can indicate the similarity of the mechanisms of the compact structures formation in both cases. The results obtained are compared with the data available for the interaction of Ag+ with DNA in solution. The mechanism of the Ag+-DNA interaction is discussed.