DNA responds to ionizing radiation as an insulator, not as a "molecular wire"

The yields of radicals trapped on DNA, measured by EPR spectroscopy of oligodeoxyribonucleotide crystals (the EPR spectrum of a single crystal of d(CCCTAGGG) is shown), are found to be very high (0.7 µmol¿J-1) and insensitive to long-range (>106 base pairs) versus short-range stacking (8 base pairs) of the bases. These observations are evidence that DNA at 4 K has the properties of an insulator and argue against DNA acting as a "molecular wire"