The activity of RNA cleaving DNA enzyme 10-23 is greatly improved by covalently introducing an intercalator, such as azobenzene, anthraquinone, 2-stilbazole, and pyrene. The intercalator is attached via an amide bond to D-threoninol, which inserts into the backbone of DNA with typical phosphoramidite chemistry. The increase of cleavage activity is observed only when an intercalator is tethered at the junction point between the catalytic loop and the binding arm at 3' side. Structures of the introduced intercalator itself as well as the linker for tethering it greatly influence the cleavage activity. In the case of anthraquinone, the most efficient activator we investigated, about eight folds of activity increase are obtained in comparison with the native DNA enzyme.