Figure 5

A) Absorbance changes of histones upon mitoxantrone binding. The reaction was carried out in 10 mM Tris-HCl pH 7.3 at 23°C. B) Fluorescence emission spectra of the histones in the presence and absence of various concentrations of mitoxantrone. All samples were prepared in 10 mM Tris – HCl (pH 7.3) and incubation time after drug addition was 20 minutes. Excitation was at 278 nm. Spectra 1–6 are 0, 10, 20, 30, 40, and 60 μM of mitoxantrone respectively. Tyr: tyrosine spectrum given for comparison.