CD spectra of (A) the unhybridized (single-stranded) PNA oligomers, and (B) the corresponding PNA-DNA and PNA-RNA (Inset) hybrid duplexes at 5 μM strand concentration each. (A) Inset: UV-absorption spectra of the individual PNA oligomers at 90 °C, showing that they had the same concentration. This indicates that the differences in the CD spectra, both the amplitude and profile, are the intrinsic properties of the oligomer themselves and not the variations in concentrations. The samples were prepared in 10 mM sodium phosphate buffer at pH 7.4, and the CD spectra were recorded at room temperature. The complementary DNA strand used was: 5'-TCAAACATGC-3'.