Sequence and chiral selectivity of drug-DNA interactions revealed by force spectroscopy.

Differential binding force has been used to precisely characterize the mechanical effect of a drug molecule binding to a DNA duplex. The high-resolution binding forces measured by the force-induced remnant magnetization spectroscopy (FIRMS) enable the binding behavior of drug molecules with different chirality and DNA of various sequences to be distinguished. The sequence specificity of Hg(2+) and daunomycin was revealed by force spectroscopy for the first time, and the results are consistent with those obtained by other techniques. Furthermore, the two isomers of d,l-tetrahydropalmatine showed selectivity for two different DNA sequences. One particular useful feature of this approach is that the small molecules under study do not require any labels.