IDENTIFICATION OF THE SOURCE OF OXYGEN IN THE ALKALINE-LABILE PRODUCT ACCOMPANYING CYTOSINE RELEASE DURING BLEOMYCIN-MEDIATED OXIDATIVE-DEGRADATION OF D(CGCGCG)

Interaction of bleomycin, Fe2+, and limiting O2 or bleomycin, Fe3+, and H2O2 with the hexamer d(CGCGCG) results in the production of an oxidatively damaged sugar lesion, 2'-deoxy-4'-pentulose, that is produced stoichiometrically with respect to free nucleic acid base release (Rabow et al., J. Am. Chem. Soc., preceding paper in this issue). Similar studies using either 180-labeled O2 or H2O have established that the source of oxygen in the 4'-keto moiety of the 2'-deoxy-4'-pentulose is the solvent. The implications of these results with respect to the mechanism of nucleic acid base release in bleomycin-mediated DNA degradation are presented. © 1990, American Chemical Society. All rights reserved.