ELECTRON MOVEMENT ALONG DNA STRANDS - USE OF INTERCALATORS AND ELECTRON-PARAMAGNETIC-RESONANCE SPECTROSCOPY

Exposure of aqueous solutions of the sodium salt of DNA to ionizing ra diation at 77 K gives trapped electron-loss and electron-gain centers in the stacked bases that were well characterized by EPR spectroscopy. We find that when mitoxanthrone and AQ(4) are intercalated, the yield s of the signals from the electron-gain centers are greatly reduced, b eing replaced by the EPR spectra of the intercalator radical anions. F ifty percent capture was observed for average intercalator separation of ca. 110 base pairs. At this concentration, the mean distance travel ed by the ejected electrons prior to any type of capture is ca. 31 bas e pairs. These results are discussed in terms of their possible releva nce to cellular DNA, with respect to both radiation damage and drug ac tion. They are also compared with extensive work of others in this gen eral area.