Effects of Sequence and Base Composition on the CD and TDS Profiles of i-DNA.

The i-motif DNA, also known as i-DNA, is a non-canonical DNA secondary structure formed by cytosine-rich sequences, consisting of two intercalated parallel-stranded duplexes held together by hemi-protonated cytosine-cytosine+ (C:C+ ) base pairs. The growing interest in the i-DNA structure as a target in anticancer therapy increases the need for tools for a rapid and meaningful interpretation of the spectroscopic data of i-DNA samples. Herein, we analyzed the circular dichroism (CD) and thermal difference UV-absorbance spectra (TDS) of 255 DNA sequences by means of multivariate data analysis, aiming at unveiling peculiar spectral regions that could be used as diagnostic features during the analysis of i-DNA-forming sequences.