On the interaction of adriamycin with DNA: investigation of spectral changes.

The aerobic reduction of adriamycin by NADPH-cytochrome c-(ferredoxin)oxidoreductase was determined spectrophotometrically and found to consist of an initial slow phase, followed by a rapid stage. Superoxide was found to play a role in the reduction of the quinone drug only during the first phase. The second, faster stage of the reaction was not inhibited by superoxide dismutase, apparently due to the decreased oxygen tension in the reaction cuvette. When adriamycin was fully bound to DNA, no direct reduction by the enzymatic system was observed. However, in the presence of a superoxide-generating system, reduction of the adriamycin-DNA complex did occur.