FIG. 3.

Binding of fluorescent G₄T₄G₄ PNA to ³²P-labeled DNA hairpin and nonlabeled C₄A₄C₄ DNA oligonucleotides. Two images of the same gel are shown: (A) ³²P autoradiography and (B) fluorescent image. A fixed concentration (0.75 μM) of ³²P-labeled DNA hairpin (left lanes on the gel), or nonlabeled C₄A₄C₄ DNA (right lanes on the gel) were incubated with increasing concentrations (values on x-axis in C) of G₄T₄G₄ PNA. Increasing amounts of fluorescently labeled G₄T₄G₄ PNA were bound to the excess of C₄A₄C₄ DNA oligonucleotide (B, right lanes). Fluorescence expressed in arbitrary units (au); PNA amount expressed in picomoles. Linear regression Y=91*X was used to calculate amounts of PNA in bands corresponding to PNA-hairpin complexes 1 and 2 (B, left lanes). Arrows 1 and 2 indicate the two shifted bands. (C) Calibration curve of the fluorescence of the bands in the gel versus amount of G₄T₄G₄ PNA.