Figure 1.

Schematic diagram of eight-ring Py–Im polyamides targeting the sequence 5′-WGWWCW-3′ (W = A/T). Dashed lines indicate hydrogen bonds between the polyamide and DNA base pairs. The γ-aminobutyric acid turn unit enforces an antiparallel hairpin configuration, and codes for W (16). Substitution of the chiral turn functionality can have substantial effects on DNA-binding and biological activity.