Oligonucleotide Spectroscopic Characterization

Unlabeled and labeled oligonucleotides were prepared in 50 mM Tris–HCl, pH 7.5, with appropriate salt as stated in the text, and had a final DNA concentration of 2.5 μM. UV or CD spectra were obtained using a UV/Vis spectrophotometer (PerkinElmer Lambda 25) or a CD spectrophotometer (Jasco J-810) measuring the sample in a 1 cm path length 3 ml or 100 μl quartz cuvette (Hellma), respectively. All melting curves were acquired at 295 nm with a gradient of 0.2°C min⁻¹. Melting curves were plotted as described in ref. (66 (link)). CD spectra were recorded at room temperature unless otherwise specified and background corrected before analysis.