Complexes of silver (I) with nucleic acids

TL;DRAbstract

The equilibrium properties of the Ag (I) complexes of DNA have been studied potentiometrically and spectrophotometrically at ionic strength of 0.1 M (NaC10[subscript 4]) and at pH's from 5.6 to 8.0. There are at least two different complexes which form at low silver ion concentrations. The strength of association of one complex (type I binding) is pH independent. The type I complexing reaction releases no protons from the DNA. A second complex (type II binding) is stronger at high pH. This complexing causes the release of approximately one proton per Ag (I) bound. DNA which is rich in GC binds Ag (I) more strongly than does AT rich DNA. However, at pH's between 5.6 and 8.0 more protons are released from AT-rich DNA's. It is proposed that the first complex (type I) involves only GC base pairs, with silver (I) adding to the sigma electrons of a ring nitrogen or interacting with the pi electrons. In the second complex (type II), Ag (I) replaces an N-1 (purine) to N-3 (pyrimidine) hydrog

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