Four genomic DNAs of differing GC content (Micrococcus luteus, 72% GC;Escherichia coli, 50% GC; calf thymus, 42% GC; Clostridium perfringens, 27% GC) have been employed as targets of interaction by the cationic polyamines spermidine {[H3N(CH2)3NH2(CH2)4NH3]3+} and spermine {[(CH2)4(NH2(CH2)3NH3)2]4+}.
In solutions containing 60 mM DNA phosphate (~20 mg DNA/ml) and either 1, 5 or 60 mM polyamine, only Raman bands associated with the phosphates exhibit large spectral changes, demonstrating that B-DNA phosphates are the primary targets of interaction.