[Effect of the molecular structure of anthracycline compounds on their intercalation into DNA]

Kinetics of interaction of rubomycin, carminomycin, and their C9-analogues with deoxyribonucleic acid have been studied by the stop - flow method. Possible reasons of nonexponentiality of the kinetic curves are discussed. The rate constants of direct and reverse intercalation of the drugs between DNA base pairs were determined and relatively small differences found for various drugs. These data and of equilibrium binding studies of interaction of the antibiotics and their analogs with DNA led to conclusion that C9-modification of anthracyclines has little effect on the binding process. That was confirmed by quantum-mechanic calculations of potential energy of interaction between various anthracycline aglicones and DNA base-pairs.