Resistance of 7,12-dimethylbenz[a]anthracene-deoxyadenosine adducts in DNA to hydrolysis by snake venom phosphodiesterase.

In enzymatic hydrolyses of 7,12-dimethylbenz[a]anthracene (DMBA)-modified DNA isolated from fetal mouse cell cultures, a low concentration of venom phosphodiesterase was sufficient for complete release of DMBA-deoxyguanosine adducts. However, efficient release of DMBA-deoxyadenosine adducts required much higher levels of phosphodiesterase. If these adducts exhibit similarly differential susceptibilities to exonucleases involved in DNA metabolism or repair, each adduct could result in significantly different biological effects in vivo.