Nature of minor-groove binders-DNA complexes in the gas phase.

The structure of noncovalent complexes of DNA duplex with minor groove binders (mG-binders) has been analyzed by state of the art molecular dynamics (MD) simulations. More than 3.3 micros of MD trajectories (including 4 x 0.5 micros trajectories) were collected for the Dickerson's dodecamer bound to DAPI, Hoechst 33258, and Netropsin. Comparison of these trajectories with control simulations in water allowed us to determine that the extreme dehydration and partial neutralization occurring during electrospray experiments does not produce the disruption of the DNA:mG-binder complexes or the dissociation of the two strands of the duplex. Irrespective of the drug and the simulation conditions the mG-binders remains bound to the DNA near the preferential binding position in aqueous conditions. Large distortions appear in the two DNA strands, which maintain however a memory of the original DNA duplex structure in water, and a general helical-like conformation.