A systematic approach toward the analysis of drug-DNA interactions using Raman spectroscopy: The binding of metal-free bleomycins A(2) and B-2 to calf thymus DNA

Bleomycins A2 and B2 are the active components in the antieoplastic drug Bl enoxane. DNA is targeted by this drug in cancer cells and the mode of actio n of this drug involves DNA binding, Ambiguity exists as to the way in whic h bleomycin binds to DNA. Raman spectroscopy was used to examine both calf thymus DNA and a bleomycin/DNA complex at two temperatures. A curvefitting technique was applied to these spectra for a spectral region obscured by ma ny overlapping bands associated with specific assigned nucleotide base resi dues. Upon binding of bleomycin, several significant changes in bandwidth, intensities, and frequencies relative to uncomplexed DNA were observed cons istently at both higher (30 degreesC) and lower (19 degreesC) temperature. The data presented here support at least a partial intercalation mode of bi nding for bleomycin that is temperature dependent and more pronounced at th e more physiologically relevant temperature of 30 degreesC. (C) 2001 John W iley & Sons. Inc.