The effect of daunomycin antitumor drug on histone H1: UV/Vis and fluorescence spectroscopy studies

In this study the interaction of antitumor antibiotic, daunomycin with histone H1 in different ionic strengths was investigated employing UV/Vis and fluorescence spectroscopy. The results show that binding of daunomycin to histone H1 reduces protein absorbance at 210 nm and the amount of denatured protein is dependent on drug concentration. By increasing drug concentration, binding constant is increased whereas denatured free energy is decreased. Increasing the ionic strength intensifies the effect. Fluorescence spectroscopy also shows that the interaction of daunomycin with histone H1 reduces the intensity of the fluorescence at tyrosine position and produces hypochromicity. The results suggest that daunomycin binds to histone H1 and quenches tyrosine residue in the protein. In the chromatin, histone H1 can also be considered as a target for antitumor anticancer drugs.