Binding of 4',6-diamidino-2-phenylindole (DAPI) to GC and mixed sequences in DNA: Intercalation of a classical groove-binding molecule

DNA intercalators typically contain planar, fused-aromatic systems that slide between base pairs in the complex. Molecules that bind in the minor groove generally contain unfused-aromatic systems with terminal basic functions. The intercalation with DNA of a group of unfused-aromatic cations, similar in structure to classical groove-binding molecules, has led to the conclusion that intercalation and groove-binding modes should be viewed as two variable depth potential wells on a continuous energy surface.