Dependence of the base sequence on the [Cu(2,2′-bipyridine)2(NO3)](NO3)-induced oxidative DNA cleavage probed by linear dichroism

Abstract

The oxidative DNA cleavage induced by the [Cu(2,2′-bipyridine)2(NO3)]NO3 (Cu(bpy)2) complex was examined using the linear dichroism (LD) technique. Using this method, the oxidative DNA cleavage by the Fenton mechanism was reported to occur through two sequential first-order reactions. As the Cu(bpy)2 concentration increased, the rate constant of both first order reactions increased, as expected. The activation energy of the second step was estimated to be 0.190 kJ mol−1. A similar method was applied for various synthetic polynucleotides. Poly[d(G-C)2], poly(dG)·poly(dC), and poly(dA)·poly(dT) produced a time-dependent decrease in LD, which could be elucidated by a single component exponential decay. This observation is in contrast to Fenton-type oxidative DNA cleavage. On the other hand, poly[d(A-T)2] produced a time-dependent decrease in the LD magnitude, which could be elucidated by two sequential first order reactions.