Perturbed gamma-gamma angular correlation studies of 111In bound to double and single stranded DNA

Using 111In as a probe, the dynamics of double and single stranded DNA have been studied by performing time-differential gamma-gamma angular correlation measurements on the 173-247 keV transitions in 111Cd. Binding of indium to DNA was investigated by analysis of sedimentation profiles, thermal transition spectrophotometry and electrochromatography. Rotational correlation times tau c greater than or equal to 400 ns and tau c = 27 +/- 7 ns were obtained respectively for double stranded (native) and single stranded (denatured) DNA. The corresponding quadrupole interaction frequencies were omega 0 = 711 +/- 15 Mrad/s and omega 0 = 151 +/- 13 Mrad/s.