On demonstrating DNA intercalation
Considerable attention has focused on new DNA-binding and -modifying agents, from natural products to wholly synthetic designs, as probes of DNA structure and as potential chemotherapeutic agents. The application of these molecules necessitates a precise understanding of the structural details of the agents' mode of interaction with the target molecule, double-helical DNA. DNA binding agents tend to interact noncovalently with the host molecule through two general modes: (i) in a groove-bound fashion stabilized by a mixture of hydrophobic, electrostatic, and hydrogen-bonding interactions and (ii) through an intercalative association in which a planar, heteroaromatic moiety slides between the DNA base pairs. Surprisingly, however, only a fraction of known DNA-interactive agents have been structurally characterized to atomic detail in noncovalent complexes with DNA.