Zn(II) complexes that trigger a DNA conformational switch

Several Zn(II) complexes are shown to produce a DNA conformational switch that involves dissociation of a fully complementary duplex into two hairpins. Of the three different pendent groups studied, a Zn(II) complex with a planar pendent connected directly to the macrocycle is the most effective at promoting the conformational switch. DNA duplexes of varying length and sequence are studied in order to examine the effect of lengthening AT tracts on conversion of duplex to hairpins. The role of hairpin structure in dissociated strands is also examined and shown to be a necessary component of an effective switch. Insight into the conformation switch is obtained through binding studies of the different Zn(II) complexes to DNA oligonucleotides that contain unpaired thymines by using surface plasmon resonance (SPR) and isothermal titration calorimetry (ITC).