RESONANCE RAMAN-STUDY OF THE BINDING OF THE ANTICANCER DRUG AMSACRINETO DNA

The binding of amsacrine [4'-(9-acridinylamino)methanesulfon-m-anisidi de] to calf thymus DNA was studied by UV-visible and resonance Raman s pectroscopy. A shift of the UV-visible absorption band of amsacrine at 434 to 442 nm together with a decrease in the intensity of this band is observed upon amsacrine-DNA binding. The resonance Raman spectrum o f DNA-bound amsacrine shows a general slight decrease in intensity rel ative to the spectrum of the free species. The significant decrease in intensity of the bands at 1165, 1265, and 1380 cm-1 upon binding to D NA is attributed to the formation of a single amsacrine-DNA species. T he assignment of these bands (1165, 1265, and 1380 cm-1), which was ba sed upon a previous normal coordinate analysis (NCA) and molecular neg lect of diatomic overlap (MNDO) calculation, and the observed lack of shift in the band positions upon binding are consistent with intercala tion being the major binding mode of amsacrine, as inferred previously by other techniques.