Equilibrium shift by target DNA substrates for determination of DNA binding ligands

An equilibrium containing the thiol derivative of Hoechst33258 (Ht-SH), glutathione (G-SH), and the corresponding homo and hetero disulfides was shifted by the addition of the duplex DNA. It was shown from the analysis of the components that the hetero disulfide Ht-SS-G increased by binding with the DNA (CA14) with an A3T3 binding motif for the structure of Hoechst33258, and that the different equilibrium shift was observed in the presence of CT14 with no A3T3 binding motif.