Figure 4.

Cleavage of DNA by AQ conjugate within PNA/DNA hybrids. Samples were prepared by mixing 5000 cpm 5′-³²P-end-labeled DNA-1X and 5.0 μM each of unlabeled DNA-1X and PNA in 10 mM sodium phosphate buffer (pH 7.0). Samples were irradiated for 60 min in a Rayonet equipped with eight lamps (λ_max = 350 nm) in colorless microcentrifuge tubes, divided in two, precipitated with ethanol, washed, and dried. One set was incubated with 100 μl of 1.0 M piperidine at 90°C for 30 min. The samples were suspended in denaturing loading buffer and electrophoresed through a 20% denaturing polyacrylamide gel. The image was obtained by scanning the autoradiogram of the gel. Conditions of irradiation or piperidine treatment are indicated above each lane. Three different PNAs were investigated: PNA(Ac) (lanes 1–4), PNA(AQ1) (lanes 5–8), and PNA(AQ2) (lanes 9–12). The sequence of DNA-1X, determined from the Maxam–Gilbert A+G and G sequencing lanes, is on the left side of the image.