Studies of adriamycin binding to histone H1 by resonant mirror biosensor and fluorescence spectroscopy

Adriamycin is a clinically used antitumor anthracycline antibiotic. Histone H1 is a target for the activity of anthracycline drug at the chromatin level. A new optical biosensor technique based on the resonant mirror was used to characterize interaction of adriamycin with H1, and the binding constant was obtained. By the analysis of fluorescence spectrum and fluorescence intensity, it was shown that adriamycin can quench the intrinsic fluorescence of tyrosine in H1 through a static quenching procedure. The binding constants of adriamycin with H1 were determined at different temperatures based on the fluorescence quenching results. The binding sites were obtained, and the binding forces were suggested to be mainly hydrophobic. The interaction of adriamycin and H1 in the presence of denaturant or salt was studied. The effect of Fe3+ on the binding constant was also investigated by optical biosensor and fluorescence spectroscopy. Furthermore, the steady-state Stern-Volmer collisional quenching study of Tyr72 with acrylamide indicated that the association between adriamycin and H1 did not change molecular conformation of H1.