where 𝐶 is the DNA concentration in mol/L (C = 2 × 10 -5 mol/L) and 𝑙 is the path length in cm (l = 0.2 cm). The CD ellipticity of DNA sequences was recorded as a function of temperature using a Jasco J-1500 spectrophotometer. The DNA concentration in the ammonium acetate solutions was 5 or 10 μM.